# Why does earth's north pole roughly point in the same direction throughout the year?

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I know there is a gioscopic explanation but I was under the impression that Earth is traveling in a straight line through space that has been curved by our sun's gravity ,so my question is why doesn't one hemisphere always point away from the sun ? It just seems like a bit of a contradiction that gravity can curve the fabric of space but has no effect on earth's axis…

It is just conservation of angular momentum. In order to change the direction of the spin axis of the Earth (which would change the direction of its angular momentum) you would have to subject it to an external torque. The curvature of space has no significant bearing on the question.

In fact the direction in which the Earth's spin axis points does change, but on much longer timescales. The "precession of the equinoxes" (as it is called) is cyclical with a 26,000 year period.

The path of the Earth in space is curved (by gravity). The explanation of gravity in Relativity is that the Earth follows a geodesic in spacetime, which is not usually a straight line in space.

A ball that is thrown will follow a geodesic, a ball that is thrown harder will also follow a geodesic. The reason that the two balls don't follow the same path, is that they are following geodesics in curved spacetime, not straight lines in curved space.

This being the case, the direction of the Earth's axis has very little to do with curved spacetime. The direction of the axis in space remains fixed, unless some force acts on the Earth to change it. The sun and moon can provide such torque (and cause precession and nutation), but this can be accurately described by the Newtonian approximation of gravity.

The main effect of the Sun's gravity on the Earth is to keep it in a (very nearly) steady elliptical orbit. So from one perspective, the Sun pulls the Earth towards it according to the inverse square law (with some rather tiny variations given by general relativity). From another perspective, the Sun's mass distorts space-time so that the natural geodesic path that the Earth follows returns to the same place (relative to the Sun and oriented by distant stars) every year. These are two descriptions of the same physics, and both are equally true (or false).

In Newtonian physics (without GR) (and assuming that both the Earth and the Sun were perfectly spherical and that the other planets did not exist) the Earth's axis of rotation would not change at all. General relativity does predict some very small changes: frame dragging and the geodetic effect. Their effect on the Earth, though is incredibly tiny. The effect of the Moon's gravity on the Earth's equatorial bulge is much greater.

## Summer Solstice is Here! Here’s All You Need To Know About Longest Day of the Year and Start of Dakshinayan

The Sun’s position relative to that of the Earth changes from East to West throughout the day. But a similar, slightly less apparent, movement of the Sun does take place from North to South throughout the year. Between such movements, two days a year, the Sun appears to ‘stand still’ as it pauses on the northern and southern limits before changing direction. These days are called the solstices—derived from Latin sol ("sun") and sistere ("to stand still")—that occur twice a year in summer (June 20-22) and winter (December 21-22).

### When is the summer solstice?

This year, the solstice occurred at 9:02 am IST on Monday, June 21, when the Sun was directly overhead the Tropic of Cancer which lies at 23.5° N latitude. Those who are at Ujjain or Gandhi Nagar in India and on the same latitude anywhere in the world will see no shadows under their feet on this day's noon.

The day also marks the maximum possible daylight hours and the most extended daytime in the Northern Hemisphere—including India. The reverse is true in the Southern Hemisphere. To clarify, June 21 is the longest day of the year in terms of more hours of sunlight—but the number of hours (24) remains the same. For instance, in Delhi, the Sun will rise at 5.24 am on this day and set at around 7.23 pm—marking nearly 14 hours of daylight.

### Axial tilt and solstice

The summer solstice marks the farthest tilt of the Sun towards the north of the Earth. It is the summer solstice for the northern hemisphere as the northward tilt of the Sun means greater solar radiation and corresponding heating of the ground for the north half of Earth.

From today onwards, the Sun will start its southward journey, also known as the Dakshinayan in India. The reason behind Sun’s apparent movement from north to south is also the cause for the very existence of seasons—the axial tilt of the Earth. So, what is axial tilt?

If you draw an imaginary line through Earth's north and south pole, the line isn't exactly vertical. Rather, the Earth has a tilt of roughly 23.5 degrees off its imaginary vertical axis—referred to as the axial tilt. Because of this tilt, the two hemispheres are either towards the Sun or away from it at different times of the year.

As the Earth rotates around the Sun, the most direct sunlight shifts between a band of latitudes, specifically between the Tropic of Cancer and Tropic of Capricorn, throughout the year. This causes the change of seasons as the hemisphere towards the Sun experiences summer and the other half winter.

### Summer solstice

On the summer solstice for the northern hemisphere, the Sun’s location is directly above the Tropic of Cancer. The north pole is tilted about 23.4° towards the Sun, which makes the rays fall directly overhead of the Tropic of Cancer, whose latitude is roughly the same 23° 3’ N. This position changes in the time frame of six months, as the Sun moves towards the South pole. The Sun then goes directly overhead of the Tropic of Capricorn, whose latitude is 23.5°S—marking the winter solstice.

In simpler words, when the summer solstice takes place in the Northern Hemisphere in June, the north pole is tilted towards the Sun and the south pole away from it. This marks the beginning of different seasons in both the hemispheres. The solstice takes place simultaneously for everyone on Earth, marking the longest day for one hemisphere and the shortest for another.

The solstice event marks the Karka Sankranti in India, marking the beginning of Dakshinayan. In Europe and parts of the US, the day is also celebrated as Midsummer's day.

For weather, science, and COVID-19 updates on the go, download The Weather Channel App (on Android and iOS store). It's free!

## Why does the angle of the Earth's tilt matter?

The Earth is an sphere. The amount of light on a sphere is not dictated by the angle it is tilted at, because its the same all around. So why does the tilt matter at all?

Edit: I am getting notifications that people are commenting but for some reason I cannot see the comments or reply, so I'll do it here.

The fact that the Earth is not in fact a sphere and is really an oval shaped thing definitely gives the tilt meaning and answers my question. It also makes me wish the Earth was not so often referred to as a sphere, a circle, a globe, because now I feel like a dumbass

Total amount of light is not the only factor affecting the climate of the earth, although it is a dominant one, and can give many insights. The tilt itself has massive consequences as well.

A cycle of seasons is a direct consequence of the tilt of earth axis. Depending on the position around the sun, different locations of earth receive different amount of sunlight per day. Effect of varying distance between sun and earth (by

3% throughout a year) is comparably tiny relative to those changes, as evidenced by the fact that north and south hemisphere have a cycle of season offset by half a year.

For the edge case, let's take the poles. If the rotation axis of the earth was not tilted, the sun would always be at the horizon, making the conditions completely unchanged throughout the year. With the axis tilted there is a massive cycle of half a year of sunlight, and half a year of darkness.

dont forget the angle of incoming light has a huge effect.. at the poles the same amount of sunlight is spread out over a much larger area than at the equator.

shine a flashlight at a piece of paper perpendicular to the light from the flashlight (Equator) note the shape and size of the light.. tilt the paper 45 or more degrees (Deep into the northern or southern hemisphere) and shine the same light on it.. the light will appear elongated and dimmer on the tilted paper than on the perpendicular paper. the same energy is spread out which means it cant warm the surface as much.

in the northern hemisphere winter the "paper" is tilted away from the incoming light and the southern hemisphere is tilted toward the light..

you forgot that the hemispheres have different landarea which absorbs/reflects light differently

The Earth is an sphere. The amount of light on a sphere is not dictated by the angle it is tilted at, because its the same all around. So why does the tilt matter at all?

This would be true if the Earth was surrounded by a light source, but light from the sun is closer to a point source. There is a decent wikipedia article on the influence of sun angle on climate, but the common demonstration we do in intro geology classes gets the point across pretty well. Take a globe, place a flashlight some distance away oriented horizontally at roughly the height of the equator of the globe and pointed at it. The beam of the flashlight is more "spread out" at the poles (i.e. less energy is reaching the surface at the poles), which in the real world can be seen reflected in terms of the total solar irradiance reaching the top of the atmosphere (i.e. the projection effect). Add to that (and as illustrated in the first wiki link), light at the poles is traveling through more atmosphere to reach the ground surface and thus more incoming radiation is absorbed by the atmosphere at the poles before reaching and heating the surface (i.e. the absorption effect). Given these effects, the tilt of the Earth's rotational axis with respect to the orbital plane influences how the irradiance at the surface in a given place changes through the year and through time (i.e. changes in obliquity. As has been pointed out by others, the oblate spheroid shape of the Earth is not the answer.

The fact that the Earth is not in fact a sphere and is really an oval shaped thing changes basically nothing about the effects of the tilt. You might as well treat it as a perfect sphere for understanding the effects of the tilt.

The fact that the Earth is not in fact a sphere and is really an oval shaped thing definitely gives the tilt meaning and answers my question. It also makes me wish the Earth was not so often referred to as a sphere, a circle, a globe, because now I feel like a dumbass

Nonononono , that's the wrong lesson. This has very little impact.

The tilt is about the fact that the rotation of the earth is tilted relative to the orbit of the earth around the sun. Imagine if the earth rotated 90 degrees away from its orbit. The north pole would always face the sun, and the south pole would always face away from the sun. If that was the case, then there would be entire days where the northern hemisphere would be completely lit all at the same time, because day and night would be dictated by where the earth was in its orbit.

> The amount of light on a sphere is not dictated by the angle it is tilted at, because its the same all around

Imagine that the tilt of the rotational axis was parallel to the plane of orbit and you live on one of the poles. In this case, you would be exposed to the sun 24/7 for half a year and in total darkness the other half. Does the tilt not matter in this case?

> The fact that the Earth is not in fact a sphere and is really an oval shaped thing definitely gives the tilt meaning and answers my question

Sorry but the earth deviates from a perfect sphere by 0.16%, this has no significant effect on the amount of light any part of it receives.

You are correct in saying that the earth will get the same amount of light regardless of tilt.

The issue is *where* that light lands, and for how long.

Lets start with a default setting, the poles are straight up and down, and you are standing at the north pole. As the earth spins you have the sun shine upon your face, then your back as you turn. Every day, the pattern repeats. Now, walk a mile or so in one direction, and the curve of the earth will hide the sun giving you "night" and "day" when your portion of the earth rotates around to bring the sun into view.

Now, tilt the earth so the north pole is pointed straight at the sun. As the earth spins, the sun simply circles overhead. never setting (as the sun is above the "pole"). So the north pole see's daylight every day, all day. period. In order for you to get "night" youɽ have to walk all the way to the equator.

As the earth orbits the sun, it stays pointing the same way..so after 6 months the south pole will be pointed at the sun, flipping the "season". Clearly, the temperature and weather will shift drastically if the sun is always up, or never rises.

The earth is tilted 23 degrees, so it isn't as drastic as this, but it gets the point across. The actual length of the day is different, causing different amounts of warming and cooling.

The other major factor is that at the poles, the ground is angled compared to the light source, which effectively spreads the light out, and you get less energy per square meter than you do at the equator. This only compounds the effect when combined with the fact that you get less sunlight in the winter, and doesn't help as much during in the longer summer days.

The literature is all over the place on some aspects of this subject. Sorely needed is a reliable source on the different issues concerning earth magnetic field

This is November 20, 2020. A few years ago, my wife and I were traveling from Albuquerque, NM, north to the State Capital, Santa Fe, which is some 50 miles way. At the south “boundary” of the city of Santa Fe is an old horse race track. As we drove past that location, the compass on my dashboard, that is encased in oil, began to spin slowly., then faster until spinning quite fast… As we continued to drive further north, the spinning slowed and then settled back to north. which was the direction we were going… WHY DID IT START SPINNING? AND THEN STOP AFTER TRAVELING ABOUT ONE MILE. Thanks for any response….

In this article [Magnetic North vs Geographic (True) North Pole],You put: “The geographic north and south poles are where lines of longitude (meridians) converge in the north.” I get confused here – why the lines of longitude converge in the north only? Is there an error here? I think it should be put instead, “The geographic north and south poles are where lines of longitude (meridians) converge in.”

Firstly, it appears to confuse magnetic inclination (ie. dip) with magnetic declination. One is vertical and one is horizontal.
Secondly, it says that, “a compass needle will point to the Magnetic North Pole”. That is not true. It will “align itself with the Earth’s magnetic field” which is completely different. Take Seattle for example. The Magnetic North Pole as of today is above Siberia (86.5°N, 164°E). This is obviously to the West of Seattle. But a compass in Seattle will point 15.55° to the East of true North. Have a look at any map of magnetic declination and you’ll see that the isogonic lines of the Earth’s magnetic field twist and turn all over the place.

@JT Allyn, I am more concerned with the fact that the deteriorating magnetic field allows more and more solar and cosmic radiation to bombard the Earth. Have you seen the stats on rapid rise of cancer patients?

I have read how the each switched poles (north for south, south for north) long ago and that they expect it will happen again.
My question is, when do we expect that to happen next?

The Earth is Tilting / Tipping . It’s very simple to figure out once you know how to control your balance with Nature .

I am stunned by the pitiful ignorance displayed in many of these posts. Please folks go back to the 5th grade and try to learn something!

I suggest you read or watch interviews of admiral bryd. It makes you wonder what the truth really is and why all the interest in things that don’t matter.

None of the comments discuss the rapidly decaying nature of the earth’s magnetic field. Since it has reduced its energy by half in less than 1500 years, I would be interested to hear what scientists think we’ll do for navigation once it’s gone… Which also begs the question: If the earth really is 4.5-or-so-billion years old, why does it still have a magnetic field at all? Anyone?

Plastic(noun), the substance, is only so called because it is, either permanently or at some point during its manufacture, plastic(adjective). Plastic as an adjective has been around for much longer, meaning malleable, which is why plastic is so called for short, having many different types with long unmemorable names.

Having said that, humans are now adding a plastic(noun) layer to the earth’s crust, including the bottom of the oceans as well as their surfaces. Long term, that is probably more harmful than climate change, which I doubt is caused by humans though certainly exacerbated by them.

Us humans will never have control of the North magnetic . The massive vortex force above us will see to that and we will have to accept that as years go on there will be a surprise where as the poles do flip . Once the gift of sound and vision is reached not many will understand.

The rigid lithosphere sits on a layer called the “asthenosphere”. It’s composition is a plastic-like fluid, which tectonic plates ride on top of. It’s from mantle convection currents where magma rises causing “slab pull”. This circular motion from mantle convection is the main mechanism that tears plates apart at divergent boundaries.

So, it’s not incorrect because there is a plastic-like layer. But yes I should have the lithosphere above it in that figure. I appreciate that for pointing it out.

Has anyone noticed, the illustration showing the earth’s cores indicates the top mantle layer is “Plastic”.

I am mistaken. Alice’s comment is how I feel too!

I haven’t seen any comments whether the removal of billions of barrels of oil has affected the acceleration of the magnetic north which is now on the move toward Siberia.

To suppose the cause of polar shift, iron relocated by mining in Minnesota, and copper from Montana? Could have affect, so we should put it all back. Silly.

Andromeda galaxy is closing on The Milkyway, our solar system crossed the equatorial center of the Milkyway 2012 science says. These are 2 possibilities for the changes around us, comfort by saying we did this and have power to change it is ludicrous.

Magnetic inclination is magnetic dip from the horizontal.

I am neither scientist nor writer, but thank you for an informative read, I may and most likely have this wrong, but here goes… true north is the point at which all longtiude lines meet? Was this location determined at the first magnetic north/South Pole reading? The true North Pole just keeps the world map the righ way up, in that instance for our human brains comprehension? My last thought, removing oil and gases (we use as energy) surely the fine mechanics of the guts of earth, perhaps need those resources to maintain the balance? For example, my car with oil or pertrol, the components in the engine cease to work! Could the removal of gases and oil, impact on earths rotation?

The pole moves? Why then does my compass point exactly where it has always pointed. The earth nor its poles are moving anywhere. This is just more made up non-sense. The north pole isn’t a place you can go and neither is the south pole. Need proof? Show me a video of a person standing on either pole looking at their compass and video this compass pointing south in all directions as the person holding the compass turns 360 degrees. Three people should be involved, the person holding the compass, the person recording the other person holding the compass as it clearly shows the direction and a third person recording the other two clearly not interfering with the compass. You will never see this because it is not possible. All you will ever see is excuses for why they can’t do it. The one thing that could easily prove that there is a south pole cannot be done.

If any of you hadn’t noticed? There are strange things happening solar system wide. The ice caps on Mars are melting, The Great Eye Of Jupiter is disappearing, our sun glows white now not yellow as in my past. Something is affecting all of it. There must be another heavenly body in our vicinity that’s passing by causing us anomalies. Climate change is made up. Carbon dioxide is what we exhale. The only answer to that is plant trees, electric cars, kill half the population. You don’t see any of those things happening in a panic. You don’t hear Russia or China talk about it at all. No they want to charge us for the air we breathe. That’s all that is about. If after 911 you believe anything the Governments says? We are in trouble!

Lol the part about a magnetic field flip taking somewhere between 200,000 to 300,000 years is just comical. Outside of its slow creep we see today, mind you that the North Pole has been moving much faster than this over the past few decades, what other evidence do you have to support this? There is so much evidence to the contrary and can be seen on every continent in the world. It can be seen in the geography of our planets, countless pre history ancient archeological sites show signs of it, our science today shows evidence of it, they have found Mammoths with intact flowers in their mouths from an event that froze them instantly. An event that occurs in semi regular intervals and that’s the field reversal. And all of them point to the potentiality of it happening in the span of a single day ! Look into it!

Oh,why?? Well, I hope you people know that in case of two magnets,the north pole of one of them,is attracted to the other magnet’s South Pole and vice versa. This is the directive property of magnets. Now, if i’m not wrong, in case of earth, which is a big magnet itself, the same will apply, along with a compass or a bar magnet hung with string which means according to our compasses, the true North Pole has the magnetic South Pole, and the true South Pole has the magnetic North Pole.(this is because when we stand facing north with a compass in our hands,the red arrow,which is the north on,will correspond to the magnetic South Pole, and vice versa.)

I used “effect” improperly in my second paragraph and can’t edit my post. (It should have been “affect” instead. Effects[noun] affect[verb] us.) I also used “steady” twice in rather bad form, later on. Sorry, Strunk & White, I’ve failed you. Feel free to ignore the rest of my blathering, if that bothers you as much as it bothers me.

What a fascinating wander and shift this conversation has had over the years. Some interesting science, some interesting theories, some interesting anti-science, and some interesting cra-cray nonsense. :P

Water doesn’t hold much magnetic charge on its own, nor does it block or otherwise effect magnetic forces. The glaciers melting won’t directly speed up, slow down, or cover up or reveal the magnetic changes that come from deep within the Earth’s mass, not on its surface. Plenty of metal on the surface, however, so locally, glacial shift and melting could occasionally, possibly, tweak a compass by a small amount over time, especially if you were exploring the glacier area itself.

Conspiratists (conspirisists?) don’t get out much. They don’t fly planes, they don’t sail ships, they don’t devote much time to looking at stars through a telescope, and they haven’t been to the top of the Burj. Air doesn’t refract light in a one-directional way as to make the Earth “look” curved. It’s actually round! Do look up the MANY scientific ways YOU can use to see it’s round and moving through space very quickly. Far from a perfect sphere, but more perfect in texture and shape than your average ping pong ball or steel bearing.

Birds don’t have magneto-vision. They don’t “see” magnetic fields, they feel them, just like we feel up and down, thanks to the moving bits inside our heads. I also haven’t heard of Western birds flying -all the way- to either North pole. They generally stop in the bulk of Canada, where the differences in magnetic North are still pretty small. As was pointed out, that line of shifting points kind of points at California, so things down here aren’t perceptibly shifting around so much.

Penguins might tell another story about the wandering magnetic South pole, but just trill and squawk nonsensically when interviewed.

In regards to the molten core shifting the way Earth moves, it undoubtedly does. The inertia of our entire world, however, remains steady enough that those shifts are slow and steady, that we can scarcely measure it. I’m sure some nerd at MIT could show us mind-numbing science on this one, but it doesn’t significantly affect our lives, so we’d all get bored and start watching lolcat videos.

If you’ve gotten to this point with a straight or angry face, I’m so terribly sorry. This post was not intended to make light of previously expressed ideas, nor ideas to come afterward. Some of you are just wrong…and that’s okay, because, thankfully, it doesn’t significantly affect the rest of our lives, so the rest of us are going to go watch lolcat videos now. Good day.

The outer core being liquid and certainly volatile, would this movement not change the angle of the earth on its axis.

Hi all please could anyone clarify if Obliquity is factored in when establishing True North and coordinates? Thanks

I am a guitarist and my choice of instrument is a Fender Stratocaster, which has single-coil pickups. In those pickups are six magnets, all in a row which is part of what makes the guitar have its unique sound. As most guitarists know, guitars with single coil pickups are noisy, introducing AC hum especially when the amplifier is cranked up and high gain and volume is used. As you hold the guitar, and face either North or South, the hum is attenuated, because you are aligning the magnets in the guitar’s pickups with the magnetic north (or south) pole. So it is not the positional relationship of the guitar to the amplifier which affects the noise, but that of the magnetic poles. Try it it works!

Sam Moe, you must be trolling. Obviously the sun would still rise in the same place if the magnetic poles reversed. The earth wouldn’t start rotating the other way. The only difference would be whether the red half of your compass needle is pointing left or right when you’re facing the sunrise.

I truly believe that this is a sign of being closer, each day, to the Day of Judgement.
When that flip happens (magnetic pole flipping), the sunrise would be from the west instead for the east. Have you thought about that ??

Obviously, the poles wander since they don’t have wives.
Have you ever watched one tie his shoes?

I often think about the birds who fly to the North and South pole regions. Unlike us humans, birds can actually see the true magnetic gravitational force. Therefore, it would make sense for them not to fly over the North pole area openings as the opening has a a force that would pull them in. There is even a restricted “No Fly Zone” concerning the North and South polar regions. Once you know where that is, you can reason where the true north really is. Because the magnetic north pole does move, you would think this to be true for birds avoiding flying in that area let alone planes. What concerns me about the changes in placements of the magnetic poles in the north is that it is shifting closer to home. It sort of reminds me of the black hole theory in space where matter gets sucked in with it if too close to it. Could this theory also be the case with the changing magnetic true North pole location?

Nobody has mentioned the changes in all our planetary bodies in last 10yrs (our sun this year has tilted by 6 degrees due to an unknown influence (if you believe NASA) these days. BTW this has nothing to do with global warming. Even our moon has strange changes going on. So our North/South poles are wandering heading in direction of Siberia, it was mentioned online somewhere that it wasn’t 44km a year now but much much faster. But true figures are being fudged again like what’s influencing our planets, the so called magnetic pole North/South shift was suggested to happen in conjuction with Nibiru/Nemisis fly around our sun again denied by Nasa causing the shift of poles and happen in minutes not years. So if this is true, airlines would have to make daily changes an be able to confirm/deny of its speedup from yearly distance to actual daily. Sadly I don’t know any pilots international or commercial pilots to ask.

I have noticed this winter especially, the Deer population has increased dramatically. I have seen multiple herds of Deer grazing around and also I have seen the Deer in the middle of town grazing on grass and twigs. They are not disturbed by the local residents nor the local pet dogs. The porcupine population is increasing as well along with more herds of Elk. As far as insects…. I have noticed more ticks the last 2 years and more worms and moths. The weather, the weather is definitely changing. It started snowing before Halloween and to this date the ground is still frozen hard and expecting more snow before the end of April.

The magnetic pole has shifted nearly 1000 miles in just 10 years, that is hardly 40 km a year. We can also see that there are now massive dieoffs of birds, animals and insects that depend on the earths magnetic field. We can also see the predicted increase in volcanic activity, earth movement and earthquakes in the last few months but no one seems to be paying any attention.

I seen in a previous post a person stated that I am no scientist. I, myself, am no scientist and I only post here to provide my own theory and hope that someone in the scientific world could tell me if I am close / in the ballpark etc. As for the flat earth I will add my own discovery! I was recently in Mexico on a wonderful vacation and the hotel we lodged at was amazing with rooms fitted with 4 foot clear glass retaining walls that overlooked the grand Pacific Ocean. Sitting on the top 24th floor I would gaze outward. Out of the corner of my eye I noticed that I could feel a definitive drop in elevation to my direct north. I crossed my one eye and kept the other eye to the West. Using the top edge of the glass retainer wall as a tool strait edge to my North with my right eye and my left eye perifialing towards the direct west, I could plainly see the curvature of the Earth / Ocean. I find it hard to believe that the glass was curved/ concave as it looked precise laser cut. I marveled at this site for the the next 6 days the slight differences in elevation, wondering how the ocean water retains its concave shape.

Back in Canada and just last night the moon was bright, not full yet however quite bright and the cloud matter was creating different shapes, with one long tail of matter reaching for the Northern magnetic. I welcome any feedback on my own theory’s and I enjoy reading all others that are posting on this topic.

Somebody mentioned the moon. I have a theory that involves the earth’s gravity keeping the moon close and in orbit. My idea is that the moon requires (absorbs) so much gravitational force when it is in line with the earth and sun, there is not enough left to hold the ocean water as close to the earth, therefore the tide gets high. But that is just my wild guess. One day, the “flat earthers” will prove us all … ROFL Pardon me. I can’t even type it with a straight face

In navigation, a magnetic compass is considered as essential and reliable tool despite of the invention of modern electronic means of determining directions. But magnetic compass needs frequent adjustments because of Polar shift theory as well as errors caused by metallic objects. In some areas magnetic compass works effectively particularly around the Equator whereby directive force is at maximum (horizontal earth’s magnetic field) which is significantly different when you are in polar areas. In this case, the operation of magnetic compass depends on the earth magnetic field

What if all the ice melts? Will that make the magnetic pull stronger?

I should have said the poles are the machines and the tails of matter are attached to the poles. The poles are still the anchor points . Don’t mind me I sometimes think too much .

I have studied expression for some time now and I feel the moon has much influence on the magnetic pull . If you look closely on a cold winter night one can see the particle matter from the moon . These particles are pulled towards the north magnetic. The poles act like a anchors and the tails from the particles are the machines in which they are attaching and slowly pulling and heaving the earth into a rotation .I feel The stars surrounding the moon have influence as well . Old earth moving techniques are a simple way to explain myself . A deadman was used . Very dangerous however they could move massive amounts of earth in one pull depending on the size of machine one would like to use. Before machines horses or ox were used . I often find myself having to go back to old school to figure the simplest.
I may not be right however I keep wondering how we rotate and thought I would add my theory . The night was cold with windchill-40 and New Year’s Eve . Sky was clear ,moon was almost at full

PKM, I’ve thought about it quite a bit lately and I was surprised to learn that there aren’t that many differences between the heliocentric and geocentric models. Both are working models.

The magnetic poles flip approximately every 10,000 years as has been documented in the carbon dating of ice and rock samples all over the earth. and it does it fairly rapidly, within ten years or so.

The magnetic north pole is in northern Canada.

I’m not a scientist, just musing. What if the melting of the glaciers, end of this ice age, has allowed freer movement of the crust and thus freer movement of the magnetic medium at the core. 800,000 years of non reversal of the poles would have to be due to some sort of change or non change that has occurred on the earth. When was the beginning of the last ice age? Does this correlate with pole reversal? Fascinating subject. Thanks for the insights everyone. Including Bingo and his alternate input. Social insights abound when everyone chimes in.

George Moorman, you can go beyond pole shifts and consider EVERY effect possible, astrometeorology might give more answers if you’re willing to put some effort into it. As much as I know is that currently most common measurements and “forecast”ing is done by measuring spots around globe and calculating through computer models expected movements of masses which are final results of weather change but not causes.

How was the compass conceived and what are the particles made of? What about the compass that influenced its action?

Bingo, if the earth wasn’t moving, we wouldn’t have days and nights, or years and months and the rest of it. Think before writing on an educational website

I’ve seen so much and yet no one knows why the poles wonders.

When I was in the military our maps would show the declination between true north, magnetic north and linear north. This was done as to find our exact position.

I wonder how airline pilots compensate for the shift. Somebody commented even 5° on a 300 mile trip can cause big problems. Wow, never thought of that.

Tomi stated in Dec 2016 that “no one lives in Antartica..” There are military bases there…you can see them on google earth.

Tomi T, thanks for the wonderful explanation with your insights…

A Russian IceBreaker Ship found true magnetic North in 2017 and NOT where NOAA predicted it would be since their last verification in 2007, it has turned 90 degrees from their ‘predicted’ easterly course and has headed due south…jet to let y’all know. What I saw 2 weeks ago on a documentary…

I also think that the climate changes we are seeing are more likely to be the result of the moving magnetic poles than CO2 emissions.

Has anyone given any thought to the changing locations of our north and south poles affecting global warming.

All very entertaining, I guess. However aviation has progressed beyond using the Magnetic NP with Inertial Nav and GPS, everything uses true north as reference. However to placate the aviation cave dwellers, we are still compelled to use magnetic references such as headings on charts and runway headings
It will sooner or later have all heading references to refer to the true north pole.

If we wait long enough, the magnetic NP will be in the southern hemisphere!!

In the mean time, Rule…… Variation (declination) East, Magnetic Least, that is to say that with easterly variation, a Magnetic heading is less than true and Variation West, Magnetic is best.

Aviation cave dwellers learn the RULE !!

I am living in northern Manitoba and just yesterday I was standing on a ancient gravel ridge and at that moment I had a feeling that to my direct north was at one time under water and to my south was high land. This of course was many years ago however… I had the feeling of being on the beach of what likely was the edge of the top of the world

Ok. Ready? True north and magnetic north. Go for a hike. #fact
The Earth is round! Go fly.
There is no actual ‘pole’ use a magnet do you see strings.

Bingo,
how come with your assumption of the earth being flat you actually have to say that ALL of the scientific research done over the past several hundred years is all false?
-You’d have to say that what people can observe via telescopes is false.
-That all the astronauts are telling lies!
-All the pilots that are flying around the world have conspired to tell us something different from what they actually experience when they fly to their destinations.
-And all of the ships captains are also sticking their heads together to tell us outright lies.
-And what is more, all of this would’ve had to be done collectively over centuries.

Bingo, you believe in fake conspiracy theories that make no sense at all.

Thank you Tomi T and everyone! The topic is interesting to say the least. Haha. Oh my goodness can you imagine when there is a flip and everyone thinks south is true north?

Reality is they are hiding the true North Pole from people with pseudo science. Along with the fact that earth is motionless and damn near everything else is a lie.
Michelson Morley, Sangac and USAF Silvertooth experiments proved quietly that earth is not moving.
So then realize this pole nonsense is a distraction.
They began changing maps decades ago to hide land. Now they just put fake ice over everything.
It’s bullocks

Tomi T Ahonen nice comment very informative. But there is a large group of people who are very effected by the variations of declination.
Pilots. True in California the difference between true and magnetic north is slight. But in locations midwest and eastern US it us 12° to 18° off. A magnetic compass is very important because it needs no electricity, it needs no calibration. But even 5° on a 300 mile trip can cause big problems.
So in the aviation community declination is a daily part of life.

NOAA what is the current position of magnetic north.

Why does NOAA not have any data of magnetic pole in last 10 years?

The north pole, is in fact the magnetic south pole. Two opposite poles attract each other. That is why the compass needle point North.

I’d like to add some thoughts from own experience. I am a Finn who did a lot of compass & map navigation in my youth, at sea and in the forests in scouting and the army. We experience this phenomenon enough for it to be relevant to naviation. So a few points to help clarify.

First, the effect of the deviance is only significant in a few parts of the world where you might experience it. If you look at the image on the page here, that has the two points, then you can see, that if someone stands in Northern Greenland, and uses a compass to determine ‘where is North’ the direction that the compass shows – is literally EXACT SOUTH. And to get to the real North pole, from that location with that magnetic compass indication, you would need to travel EXACTLY EAST.

So in VERY Northern (or very Southern) parts of the planet, the distortion to the compass can be dramatic. Now Finland is the Northernmost country on the planet (when countries are compared measuring their geographic midpoints) so as a nation, we are ‘most affected’ by this in terms of distance from the actual North Pole (if Greenland becomes Independent as Kalaalit Nunaat then it would assume this honor from Finland as the Northernmost country). But even in Finland, the typical error for a compass pointing North, and True North is something like 6% to 11% depending on where you are in FInland (effect is strongest in the North, weakest in the South). Now how many people live on the islands of Canada, or in Alaska, or in Norway, Sweden, Finland in Northern areas of Russia, in Iceland, on the Northernmost island of Japan (Hokkaido) or yes the Greenland province of Denmark? If we say 100 million people that may be roughly the ball park (nobody lives on Antarctica, where the same phenomenon would also exist). But of the planet’s 7.5 Billion people that is a bit over 1% of all humans.

For the other 99% this will not really matter, except for the couple of Arctic fanatics who may want to explore the North (or South) Pole haha. And note, Finland has this effect in an exceptionally great degree, and even with us, the compass is ‘off’ by only under 10 degrees in typical situations (a compass dial has 360 degress so that is about 3% error).

We learn about this in school and we learn about it a lot if we get involved in compasses and mapping and navigation if in boating or scouting or any other navigation needs in Finland, plus of course we learn about this in the army (all Finnish men have to serve a year in the military). It is a real phenomenon but like I said, it only impacts the extreme Northern and Southern parts of the planet. It ALSO has a relevance limit by the East/West area. WITHIN the Northern (or Southern) Hemisphere, the FURTHER away East or West you are from Magnetic North, the more it can be measured. Let me show again with the illustration from the above.

Where the arrow points to ‘Magnetic North’ – if you follow that line South, to where the second big circle encircles the globe, that is roughly California. From California facing ‘Magnetic North’ there is no difference to real North. Even though the compass points to ‘closer’ than real North, both point GEOGRAPHICALLY in the same direction, into true North. The same would be true if you were opposite that point in Russia, in Siberia, then the compass would point ‘beyond Real North’ but the DIRECTION is identical with Magnetic North. So if you happen to be ‘directly South’ of where Magnetic North Pole is, or exactly opposite that on the other side, then there is no difference to what the compass shows and what is True North. But the further you move either East or West, so if you go the furthest East, you’d be in Iceland, and furthest West you’d be in Japan, those areas experience the worst distortion on the same latitude.

With this to add to my original guess of about 100 million people impacted, the reality is that probably only about 2/3 of those people are in both North-enough area, and far enough East/West to notice this phenomenon. Thats well less than 1% of the human population. But us in the Nordics (Scandinavia and Finland) and those in the Furthest East Asia, NorthEast Russia (Vladivostok) and Japan Hokkaido etc, they will yes, see a big difference in their compass reading vs real North.

Tomi Ahonen
In my day job, I’m a tech author

True, the earth’s mag. field is not a perfect bar magnet. There is much more variation in the field at other, smaller scales, including areas where North and South change by > 45 degrees over < 100 km in Australia. Plus, there is reason to think the strong North / South dipole changes to a weak four pole (tetrahedron) field in between field reversals. – Randal O.

This is part bunkum. A magnetic compass most certainly does NOT POINT to the ‘magnetic north pole’. Any reasonably accurate mapping of the geomagnetic field shows lines of force (along which a magnetic needle will align itself), and they wander about creating patterns significantly different from longitude – like lines. This is rather elementary.

Hello,
I believe “theory” is the scientific term for our knowledge of a subject at the current moment. The term “hypothesis” is used for scientific guesses still to be proven.
Thanks. Yours, Josie

H.Laldinmawia – Depending on which country you live, you either subtract or add the magnetic variation if you are using a compass.

how can i calculate the exact true north from Magnetic north (pointed by my compass)?

The geographic north pole mark the end of the axis
The magnetic north pole is near but does not reach the axis

“the Magnetic North Pole is actually moving kilometers every year. This phenomenon is known as the Polar Shift Theory”

No, I don’t think so. You don’t use the word ‘theory’ to describe an observed phenomenon. ‘Magnetic polar wander’ would be much closer to the mark.

When was this article written? It is using very outdated images. It is showing 2007 at the last verified magnetic north location. With the number of things like the thousands of planes in the air at any given time I would think a verified magnetic north point would be simple. What is the latest verified magnetic north location? What is the daily variation?

## Why does earth's north pole roughly point in the same direction throughout the year? - Astronomy

I shared the fact that I celebrate the pagan holiday of winter solstice with some kindergardeners at the elementary school where my daughter attends second grade [I avoided the word 'pagan' like the plague]. It helped fulfill some International Bacclaureate requirement. I brought a globe and a little model sun that Chick-fil-a was giving away and explained about earth tilt and seasons and the Tropic of Capricorn [can you say 'Capricorn' boys and girls?]. But it got me thinking . why does the earth tilt? Or more specifically why would it stop and reverse directions on a regular basis? I searched the web and got some stuff about ancient asteriod strikes. Which I can see if the Earth continued to tumble end over end. But it doesn't. So here's my ultimate question. Has anyone built a computer simulation of a primordial Earth complete with asteriod collisions that in fact models a highly periodic oscillation of 23.45 degrees from the celestial elliptic?

Becuase of the misleading way that the reason for the seasons is explained (ie. as being due to the Earth tilting towards and away from the Sun), it is a common misconception to believe that the Earth actually tilts back and forwards once a year. This would be a very strange thing to happen and I can see why you would be confused trying to come up with an explanation for it!

What's actually going on is that the tilt of the Earth always points in the same direction, but as the Earth orbits the Sun the orientation of the tilt with respect to the position of the Sun changes. There is a simple demo for this. Take a pencil and tilt it at roughly 23.5 degrees with respect to vertical. This pencil should always tilt in the same direction with respect to the walls of the room you are in. Now move the pencil in a big circle around some fixed object in the room. On one side of the object the pencil tilts towards it, while on the other side it tilts away. With respect to the walls of the room (etc) it always tilts in the same direction.

Diagram illustrating this for the Earth-Sun system:

#### Karen Masters

Karen was a graduate student at Cornell from 2000-2005. She went on to work as a researcher in galaxy redshift surveys at Harvard University, and is now on the Faculty at the University of Portsmouth back in her home country of the UK. Her research lately has focused on using the morphology of galaxies to give clues to their formation and evolution. She is the Project Scientist for the Galaxy Zoo project.

## North Pole

The North Pole is the northernmost point on Earth. It is the precise point of the intersection of the Earth's axis and the Earth's surface.

From the North Pole, all directions are south. Its latitude is 90 degrees north, and all lines of longitude meet there (as well as at the South Pole, on the opposite end of the Earth). Polaris, the current North Star, sits almost motionless in the sky above the pole, making it an excellent fixed point to use in celestial navigation in the Northern Hemisphere.

The North Pole sits in the middle of the Arctic Ocean, on water that is almost always covered with ice. The ice is about 2-3 meters (6-10 feet) thick. The depth of the ocean at the North Pole is more than 4,000 meters (13,123 feet).

The Canadian territory of Nunavut lies closest to the North Pole. Greenland, the world's largest island and an independent country within the Kingdom of Denmark, is also close to the pole.

The North Pole is much warmer than the South Pole. This is because sits at a lower elevation (sea level) and is located in the middle of an ocean, which is warmer than the ice-covered continent of Antarctica. But it's not exactly beach weather. In the summer, the warmest time of year, the temperature is right at the freezing point: 0 degrees Celsius (32 degrees Fahrenheit.)

Because the Earth rotates on a tilted axis as it revolves around the sun, sunlight is experienced in extremes at the poles. In fact, the North Pole experiences only one sunrise (at the March equinox) and one sunset (at the September equinox) every year. From the North Pole, the sun is always above the horizon in the summer and below the horizon in the winter. This means the region experiences up to 24 hours of sunlight in the summer and 24 hours of darkness in the winter.

Drifting Research Stations

Since the North Pole sits on drifting ice, it's difficult and expensive for scientists and explorers to study. There isn’t land or a place for permanent facilities, making it difficult to set up equipment.

The most consistent research of the North Pole has come from manned drifting research stations. Russia sends out a drifting station almost every year, all named "NP" (for North Pole). Drifting stations monitor the ice pack, temperature, sea depth, currents, weather conditions, and marine biology of the North Pole.

As their name implies, drifting stations move with the drifting ice pack in the Arctic Ocean. They usually last two or three years before before the warmer climate of the Greenland Sea breaks up the ice floe.

North Pole drifting stations are responsible for many discoveries about the ecosystem at the North Pole. In 1948, for example, bathymetry studies revealed the massive Lomonosov Ridge. The Lomonosov Ridge is an underwater mountain chain stretching across the North Pole, from the Siberian region of Russia all the way to Ellesmere Island, Canada.

Drifting stations have recorded the development of cyclones in the Arctic, as well Arctic shrinkage. Arctic shrinkage is climate change in the Arctic, including warming temperatures, the melting of the Greenland ice sheet (resulting in more freshwater in the marine environment), and a loss of sea ice.

Ecosystems at the North Pole

Polar bears, Arctic foxes, and other terrestrial animals rarely migrate to the North Pole. The drifting ice is an unpredictable habitat, and does not allow for regular migration routes or the establishment of dens in which to raise young. Still, polar bears sometimes wander into the area in search of food.

The undersea ecosystem of the North Pole is more varied than the ice above it. Shrimp, sea anemones, and tiny crustaceans inhabit in the area. A few ringed seals have been spotted. (Ringed seals are common prey of the polar bears that wander into the region.) Larger marine mammals, such as narwhal whales, are much more rare.

Several species of fish live at the North Pole. Arctic cod are the most abundant. Arctic cod are small fish usually found near the seafloor, close to their food sources—tiny shrimp and crustaceans.

Birds are frequent visitors to the North Pole. The Arctic tern, which has the longest annual migration of any species on the planet, spends its spring and summer in the Arctic, though rarely as far north as the North Pole. It then flies 30,000 kilometers (18,641 miles) south, to the Antarctic Circle. The Arctic tern makes an Arctic-Antarctic round-trip migration every year.

Like the Arctic tern, all other birds spotted near the North Pole are migratory. They include the small snow bunting and gull-like fulmars and kittiwakes.

Exploration

Major polar exploration began in the 19th century. The first expedition specifically to reach the North Pole was led by British Admiral William Edward Parry in 1827. Norwegian explorers Fridtjof Nansen and Hjalmar Johansen attempted a land-based expedition in 1895. A Swedish expedition led by Salomon August Andree tried to fly over the North Pole in a hydrogen balloon two years later.

The first person to claim reaching the North Pole was American explorer Frederick Albert Cook, in 1908. Cook was unable to provide any navigational records of his achievement, however, and rest of his team later reported that they did not quite reach the pole. The claim remains controversial.

A year later, another American explorer, Robert Peary, claimed to reach the North Pole. Peary was supported and funded by the National Geographic Society, which verified his claim. It has been in dispute ever since.

Although Peary's North Pole team included four other people, none of them were trained in navigation. They were therefore unable to verify Peary's claims, and one of them, Matthew Henson, reported a conflicting route from Peary. Peary himself never made his navigational records available for review. Skeptics have noted the remarkable speed with which the expedition traveled once Capt. Bob Bartlett, the only other navigator, left the crew. Peary reported more than doubling the amount of territory covered daily as soon as Bartlett left the expedition.

Nonetheless, many explorers support Peary's claims. National Geographic conducted extensive studies of the photographs Peary took, and concluded they were taken within 8 kilometers (5 miles) of the pole. (The photographs themselves have never been made public.) Depth soundings taken by Peary and Henson also seem to support their claim to have reached the pole.

Perhaps the most important support for Peary's claim came from British explorer Tom Avery's polar expedition of 2005. Avery mimicked Peary's supposed route, using sled dog teams. The expedition successfully reached the North Pole.

The first verified expedition to the North Pole was conducted by Norwegian explorer Roald Amundsen in 1926. Amundsen did not use a ship or dogsleds—he flew over the pole on the airship Norge. The Norge, lifted by hydrogen and powered by a diesel engine, flew over the North Pole on its route from the Norwegian Arctic to the U.S. state of Alaska.

The first people verified to have set foot at the North Pole were a research group of geologists and oceanographers from the Soviet Union in 1948. The scientists were flown in and out of the pole over a three-day period.

The first watercraft to reach the North Pole was a nuclear-powered submarine, the USS Nautilis, in 1958. Another U.S. submarine, the USS Skate, broke through the sea ice to surface near the North Pole about a year later.

The first verified expeditions to reach the North Pole by foot didn't happen until the late 1960s. A team led by American explorer Ralph Plaisted used snowmobiles to reach the pole in 1968. A year later, an expedition led by British explorer Wally Herbert reached the pole on foot, with the aid of dog sleds and airlifted (flown-in) supplies. In 1986, 77 years after Robert Peary made his claim, a team led by National Geographic Explorer Emeritus Will Steger became the first verified expedition to reach the North Pole by dogsled without resupply.

Shipping through the North Pole

Today, large, powerful ships called icebreakers are often used to navigate the ocean around the North Pole. Icebreakers carve through the sea ice to make way for cargo and military ships.

Icebreakers have very strong steel bows that can break through ice at a rate of about 10-20 knots (19-37 kilometers per hour, or 12-23 miles per hour). Until the 1990s, all icebreakers that traversed the North Pole were nuclear-powered. Arctic shrinking and the reduction of sea ice have since allowed diesel-powered icebreakers to navigate the North Pole.

Fewer icebreakers may be needed in the future. Due to Arctic shrinkage, within 50 years the North Pole may be ice-free in the summer months.

Cargo ships traveling between Asia, North America, and Europe save money by navigating the so-called Northern Sea Route, a trade route which often includes the North Pole. Ships carrying cargo such as oil, natural gas, minerals, and grain regularly use the Northern Sea Route. This saves companies hundreds of thousands of dollars by avoiding the long trip to and through the Panama Canal.

Resources and Territorial Claims

No one actually lives at the North Pole. Inuit people, who live in the nearby Arctic regions of Canada, Greenland, and Russia, have never made homes at the North Pole. The ice is constantly moving, making it nearly impossible to establish a permanent community.

The Arctic Council, composed of nations with territory in the Arctic Circle, addresses issues faced by nations and indigenous people of the Arctic, including the North Pole. Canada, Denmark, Finland, Iceland, Norway, Russia, Sweden, and the United States are members of the Arctic Council.

The possibility of an ice-free trade route between Europe, North America, and Asia makes the North Pole an economically valuable territory. Oil and gas exploration have proved lucrative in other parts of the Arctic, and the possibility of extractive activity around the North Pole's seabed interests many businesses, scientists, and engineers.

However, taking advantage of sea routes or resources at the North Pole is politically delicate. The North Pole is in the middle of the Arctic Ocean, outside the territorial claims of any nation. However, international laws allowing nations to claim land extending along their continental shelf are currently being explored.

Russia, Canada, Denmark (via the independent country of Greenland), and Norway have all claimed areas extending from their continental shelves, with Canada and Russia voicing the strongest claims.

In 2007, a Russian research expedition using sophisticated submersibles became the first to descend to the actual seabed beneath the North Pole. The expedition, Arktika, planted a titanium Russian flag on the spot.

Other Arctic nations reacted strongly. The United States issued a statement dismissing any Russian claim to the region. Canada's Minister of Foreign Affairs used a line from the Canadian national anthem in a rebuke: "This is the true north strong and free, and they're fooling themselves if they think dropping a flag on the ocean floor is going to change anything."

Russian leaders acknowledged Arktika was an expedition to prepare evidence supporting the North Pole as part of the Lomonosov Ridge—an extension of the continental shelf off Russia. However, expedition leaders questioned other Arctic nations' reaction.

"When pioneers reach a point hitherto unexplored by anybody," the Russian Minister of Foreign Affairs said, "it is customary to leave flags there. Such was the case on the Moon, by the way."

Photograph by Tareq Onu, MyShot

North Pole is a town in central Alaska. It is actually nowhere near the real North Pole, which is in the middle of the Arctic Ocean.

H0H 0H0
That's the Canadian postal code for the North Pole, a reference to the area's most famous mythical resident, Santa Claus.

Flight Time
Airlines flying from North America and Europe to Asia can save time and costly fuel by flying over the North Pole instead of in a straight line around the widening globe. This only became possible after Russia allowed commercial airliners to fly over Siberia in the early 1990s.

No Time at the Poles
Time is calculated using longitude. For instance, when the sun seems directly overhead, the local time is about noon. However, all lines of longitude meet at the poles, and the sun is only overhead twice a year (at the equinoxes.) For this reason, scientists and explorers at the poles record time-related data using whatever time zone they want.

Wobbly Definition
The Earth's axis wobbles slightly. This causes the exact location of the North Polethe intersection of the axis and the Earth's surfaceto wobble along with it. The precise location of the intersection at any given moment is called the "instantaneous pole."

Mathematicians have calculated the wobble, called polar motion, to about 9 meters (30 feet) over about 7 years. The phenomenon is called the Chandler wobble.

## Ep. 51: Earth

Another week, another planet. This time we talk about our own home world: Earth. You might think you know the planet beneath your feet, but it’s actually one of the most interesting and dynamic places in the Solar System. Learn about our planet’s formation, weather, its changing climate, and life.

### Transcript:

If youâ€™re going to be in the neighborhood, if youâ€™re going to attend the conference, come by the Podcast area and meet Pamela.

Okay, letâ€™s continue on then, another week another planet. Last week we covered Venus so that means itâ€™s our home planetâ€™s turn. Letâ€™s talk about Earth. All right Pamela, talk about Earth.
Pamela: Well, Earth is perhaps one of the geologically most interesting planets in our Solar System. There are a few moons that are out there contending for being most interesting geological object in general. As far as the planets go, Earth has the most going on.

We have plate tectonics. We have an active magnetic field. Weâ€™re not 100% stable in our orbit so all the little irregularities that cause twisting and turning, cause our atmosphere and our weather patterns to constantly be evolving and we have cycle within cycle within cycle of change constantly going on. And, we have life.
Fraser: Fortunately we live on the Earth so we are at good proximity to study it. So letâ€™s start then with the formation. Once again, do you want to tell the story of our planetâ€™s start?
Pamela: Well our planet like pretty much all the other planets in the solar system started out as a whole bunch of dust grains orbiting the sun while the sun was in the process of forming. These dust grains collided and merged and merged until we eventually got a nice big blob of stuff.

That blob of stuff was hanging out doing its best job to cool and solidify, cool and solidify and form a planet, when along came something Marsish in size and knocked the tar out of it.

In the process a lot of the light stuff that had been on the surface of that forming blob of planet Earth, got knocked into outer space. It re-solidified to form the moon and the heavy stuff got left behind to stay the planet Earth.
Fraser: We actually did a whole episode on the formation of the moon. So, although Pamela just went right past that really quickly you can hear the whole story that we will link from the show notes.

Okay so we have got the Earth as a blob and the moon as another blob of lighter elements. What next?
Pamela: So these blobs were really hot. They started off just not the type of place you would find liquid water. The moon stayed someplace where we still donâ€™t have liquid water on the surface of the moon. The moon is too small to have an atmosphere so any liquid that is on its surface just instantly goes straight to vapor and escapes.

Thereâ€™s ice on the moon, but that ice does not actually come from the stuff the moon formed out of. It comes from comets hitting the moon. And on Earth, all of the water on the planet Earth we think also comes from comets hitting the planet.

We start off with a hot lava blob that is mostly heavy stuff. As it cools, we enter a solar system period called the great bombardment. The planet gets totally blasted with comets. Comets hit the planet, melt and create the oceans.

The continents basically rose out the oceans. We had all sorts of volcanoes, and they burbled stuff to the surface. Because we have so much liquid, our planetâ€™s plates (places where large amount of crustal material came to the surface) are able to slide around. The water actually works as a lubricant to help plate tectonics. Plate tectonics are a good thing.

Our planet is still working on cooling off from its original formation. Part of that cooling off means heat has to escape. Itâ€™s like when you have a pot of boiling spaghetti noodles with a lid on it. The lid will rattle and move around as blobs of steam try to come out of the surface.

Now if you locked that lid on, if you made your pot into a pressure cooker, it could actually explode from the pressure built up inside. That is kind of what Venus does when it resurfaces its entire surface in one foul volcanism swoop.

Here on Earth we have constant slow escape of the heat inside the planet. Some of that heat is not just coming from the planet still cooling off it is actually being generated from nuclear materials inside our planet decaying. Our planet is actually a wee bit radioactive and any of you who live near granite quarries know that because you have radon building up in your basement from the decay of radioactive materials in granite.

That constant decay is also heating our planet, also escaping through the surface. The places where a lot of this heat is escaping, this forms the Pacific ring of fire where we have volcanoes in Hawaii, we have the Indonesian islands that get unfortunately hit with earthquakes on a regular basis as the planet shifts and moves.

We have one crustal layer plunging underneath another one near Peru, which recently caused a large earthquake. We have parts of Ethiopia actually tearing itself apart as our planet is constantly rearranging its surface.
Fraser: Is the plate tectonics we know today whatâ€™s been happening across the Earth for a long time or are we in a less active phase then what used to be? What does the future hold? How will things play out over time?
Pamela: As our planet cools, the plate tectonics is getting slower and slower. There is less heat that needs to escape so there is less pressure building up underneath the surface moving everything around.

Other things are less dramatic than they used to be. At different points in the Earthâ€™s geologic history all the crust has been lumped up in one place. This actually causes the mass distribution of the Earth to be slightly different. You have all of the planetâ€™s water on one side and all of the planetâ€™s earth on the other side.

This can actually cause our planet to change how it is oriented relative to its north and south rotational poles. The north and south pole will stay roughly in the same alignment relative to the Sun, but the planet relative to that axis can actually pivot dramatically so that the big mass parts are along the equator and the low mass parts are near the poles. This is a more stable way for it to rotate.
Fraser: How much in the past has it changed?
Pamela: It is hard to go back and figure out exactly how much it has changed but we know that there have been some dramatic alignments. These are the type of alignments that if they occurred today would take Alaska and put them on the Equator. These rearrangements are documented in the magnetic rock. As rock comes up through lava vents (basically comes to the surface) it has things that can hold on to magnetic fields within it.

As that material cools the magnetic bits in the rock will align themselves relative to the Earthâ€™s magnetic field. The magnetic fieldâ€™s orientation is based somewhat on the rotation of the planet. Whatâ€™s happening here is, we have (with the planet Earth) a solid core, it sits there. Around that solid core is molten iron. As that molten iron rotates, it has charged particles within it. Those rotating charges create a magnetic field.

As long as that rotation is going in roughly the same direction, the magnetic field stays roughly oriented the same. It tends to sloosh and move around a bit, but while its poles may switch, it generally stays oriented roughly along the rotation of the planet. North and South may switch but the direction of the poles stays roughly related to how the planet is rotating. You donâ€™t end up with North coming out through equatorial Africa in general.
Fraser: But there are processes that do change the direction of the poles.
Pamela: There are processes that change the direction of the poles. Those processes generally keep the poles and the rotation axes of the planet roughly aligned with one another. Ninety-degree angles do not generally happen.

But when we are going through the sedimentary rock we occasionally find these places where the rock is just oriented wrong. We think that this is related to the planet actually slooshing. This is called true polar wander.

This happens when you end up with the planetâ€™s water and mat crust oriented in strange ways and the planet has to realign itself so that its mass is distributed in a way that allows it to rotate stably. It is a really weird phenomenon.
Fraser: Can we talk a bit about periods of heating and cooling? I know that part of the polar tilt has a role to play in that as well.
Pamela: In addition to this really weird true polar wander that is a very rare and non-periodic occurrence, we do have these constant periodic changes going on. This is called Milankovitch cycles. The Milankovitch cycles are a bunch of different cycles layered on top of one another.

They cause these long-term periodicities in our climate. You have effects due to procession. This is how the Earthâ€™s north and south poles stay at the same angle relative to our orbit around the sun but where that angle is pointed changes. So, our North Star doesnâ€™t always stay our North Star.

Sometimes you actually end up with a southern polar star, which we donâ€™t currently have. Depending on how our poles are aligned, you end up with different extremes in the seasons. Currently during the northern hemisphere winter, we are actually closest to the sun, so when the North Pole is pointed toward the sun the planet is also closest to the sun.

When we are closest to the sun we get about 6.8 percent more light than we do when we are furthest from the sun. Because of this, the northern winters arenâ€™t as extreme as the southern winters. We can also at different points in the Earthâ€™s procession have the South Pole pointed at the sun when we are closest to the sun.

We can end up with the poles not pointed at the sun, just at a wide angle when we are closest to the sun. All of this affects the extremes of the seasons. We also have affects that are caused by the eccentricity of the orbit. Jupiter, Saturn and all the other planets are constantly pulling on the planet Earth.

This causes the actual shape of our Earth to gradually change. Sometimes the Earth is going to be further from the sun sometimes the Earth is going to be nearer to the sun, and how much nearer and how much further changes over time. Currently the difference between when we are closest and furthest to the sun is 6.8 percent more energy when we are closest. Sometimes we can get to the point that it is more than 20 percent more light when we are closest to the sun.

This also affects the seasons, making the seasons more extreme. Our sun itself is slowly changing. All of these different things are piling up on top of one another. Our axial tilt is also slowly changing. While we are more or less about 24 degrees, our axial tilt wanders from about 21.5 to 24.5 degrees. We are currently 23.44 degrees.

All of these different things pile up on top of one another to affect the seasons. This actually shows up in long-term understanding of climate where we take ice cores from glacial areas and we study â€œHow has the planetâ€™s temperature varied over hundreds of thousands of years?â€
Fraser: We are going to throw all of that data into chaos this century with our human made global warming. [Laughter] But, thatâ€™s completely different.
Pamela: True. Unfortunately as we look at all these cycles we do see long-term cooling and heating trends and we are in what is supposed to be a normal heating trend, except we sort of shot off what is normally predicted.
It is kind of like if you are used to coasting your car down a hill and you know if you are going at 40 miles per hour at the top of the hill as you start going down the hill you just throw it into neutral and just let it go and you will be going 50 or 60 at the bottom of the hill. Imagine trying that experiment one day and all of a sudden you are going 300 miles per hour when you hit the bottom of the hill.

Thatâ€™s just not normal and currently we are in one of these â€œthe car is really accelerating far more than it should beâ€ heating phases and we are trying to fully uncouple all of the different effects of our atmosphere.
Fraser: All right so we have talked about the ground itself, letâ€™s talk a little bit about the weather. So, what are the processes that get our weather whipping up?
Pamela: Well, our weather comes from a lot of different things. It comes from the fact that as our planet rotates different sides of the planet are differently heated. Anytime you have one side cold, one side hot, you are going to end up with airflows.

We also have one side of the planet pointed more to the sun than the other, so you end up with day in one hemisphere is warmer than day in the other hemisphere. This ends up with different airflows. Then the planet is just rotating relative to the atmosphere. All of these different rotations cause the atmosphere, which is basically fluid, to end up convecting.

We also have oceans that hold onto the heat and transfer it themselves. There are mid-ocean conveyor belts that are driven by both changes in salinity and changes in temperature in different parts of the ocean. So you end up with cold air in the northern hemispheres oceans sinking down to the bottom, flowing down towards the equatorial regions where they heat up, rise to the surface. Then this warm water goes across the surface of the oceans back up to the northern extremes.

So, you have this constant conveyor belt of hot and cold water. As the cold water comes down to the mid latitudes it cools off the oceans and this helps temper our hurricanes. The warmer the water is, the more powerful the hurricanes can become. Then we also have this warm water going north and warm water actually helps warm the air allowing moderate climates to occur in nations like England.

If this conveyor belt shuts off, which it can do if you dump too much fresh water into the northern oceans, then you end up with extremes. You end up with the equatorial oceans getting hotter and hotter and hotter and that heat isnâ€™t getting conveyed up to areas around Europe and Japan. So, those climates start to get a lot colder and you can end up with much more extreme conditions here on the planet Earth.
Fraser: Now we talk about with all of the planets that we have gone through so far (and I am sure when we get to Mars we will talk about this as well) and itâ€™s about the search for life. Well, I think we found life here. Iâ€™m pretty sure.
Pamela: I think so. Not always sure. [Laughter]
Fraser: Okay. So, how do people think that got started?
Pamela: Well our planet is about 4.6 billion years old. We think that roughly 4 billion years ago, small single celled organisms started to pop out on our planet. From these single cells over time, things slowly got more and more complicated. We are still trying to sort out all the different states. How did this evolution take place? It is not something that we can resurrect in a lab. It is not something we can repeat and try over.

As near as we can tell, about 4 billion years ago single celled organisms began to exist. Originally there were probably things called methanogens that didnâ€™t work the way life that we are used to worked. They didnâ€™t require oxygen, in fact oxygen killed them, and they produced methane that probably helped warm our planet.

Methane is a greenhouse gas. This is why we are currently so concerned about things like moose in the Scandinavian nations that are giving off methane through processes best not talked about in an astronomy show.

So these methanogens gave off methane, helped keep the planet warm and then at some point they evolved. We ended up with new types of cells that instead used and produced oxygen. Our atmosphere radically changed.

We think about this same time, probably about 3 billion years ago, cells developed a way to use photosynthesis to better utilize energy from the sun. They used this photosynthesis to trap carbon and release oxygen into the atmosphere.

This killed off all methanogens and started creating an atmosphere that would be conducive to the type of life that exists now.
Fraser: I think it is amazing that the oxygen that we need to breathe today started out as a harmful by-product of that class of bacteria. [Laughter] It was a toxin.
Pamela: You know sometimes what is bad for one thing is really good for another thing. We have all had our own evil thoughts at different points. If only bad thing fu would happen then it would be really good for us.

Well in the case of life the processes that killed off all of the happily existing methanogens opened the door for different forms of bacteria and eukaryotic cells that were able to build up into the animal, plants and fungal cells that we have in all of our modern life forms.
Fraser: And the bacteria has spread to every corner of the Earth, not to mention us here up on the surface, but there is lots and lots of life just underground, bottom of the oceans, its everywhere.
Pamela: It is everywhere. Some of the cool things that we are discovering are just the ways that life has figured out to protect itself under hostile conditions. If you wander through the desert after a rainstorm, every little puddle you find is going to be teaming with life.

When these puddles dry up, where does that life go? It turns out that life stays right there but itâ€™s able to encapsulate itself to protect itself to basically find ways to completely shut down and go dormant in some cases for hundreds of years waiting for the next puddle to form that it can live in and thrive in and reproduce in. So, no matter how hostile our planet gets, different forms of life find ways to survive within that hostility.
Fraser: I think these discoveries in the last few decades have made me feel a lot better about global catastrophes or even human made catastrophes. Like when another big asteroid hits the Earth and causes a mega extinction event, there are whole ecosystems that are completely disconnected from the sun and if it is cloudy for a hundred years they donâ€™t care. [Laughter]

I think that is actually quite amazing that before we thought everything was so fragile, but in fact the Earth is quite durable and life has hit every niche and has many places that donâ€™t rely on the sun for energy. So we less have to worry necessarily that life on Earth is going to survive and more just about ourselves.
Pamela: Yes, multi-cellular life, which has only been around for basically the past billion years, is fairly fragile. We die fairly easily.

Everyone has witnessed the death of an earthworm on a sunny day. We are fragile. The bacteria are here to stay. The microorganisms are here to stay. Itâ€™s the bigger things.

Animals as we know them have only been around for 600 million years. Things as simple as a fish have only been around for 500 million years. Insects started 400 million years ago on our 4.6 billion year old planet. Mammals are only 200 million years old and humans are only 2 million years old.

We are fragile, it took a long time to get to us, but I have faith those microbes as long as there is a planet Earth, there is going to be some single celled organism living on it.
Fraser: So what does the future hold for our planet?
Pamela: Well, it depends on global warming. We live in an interesting time where the future of our planet is being defined today. But setting global warming aside, assuming that our atmosphere is able to return to the normal cycles of the Milankovitch cycle that it had gone through for the past billions of years, our planet should be okay for another 50 million years or so.

We are actually in the twilight of our planet. In the next tens of millions of years our sun is slowly going to warm and as it slowly warms it is going to slowly warm our planet. Eventually it is going to reach the point that our oceans start to boil and evaporate. When this happens we are going to have two different problems.

The first problem is it is too hot for life like us to exist. Once the oceans start evaporating, that water in the atmosphere is going to increase the heating of the planet. Water vapor is just another greenhouse gas.

Once our planet starts baking, the water is going to bake out of the Earth itself and we are going to have a problem a lot like Venus where the plate tectonics no longer has a lubricant to allow the plates to gradually shift. So the heat starts building up inside the planet as well where you can start getting catastrophic volcanism going on.

All in all, life is not going to be happy in about 50 million years. The sun is going to stay at a safe distance for another 5 billion years or so, but in about 5 billion years our sun itself is going to start going through changes in how it generates energy. This is going to affect the radius of the sun.

It could come out and get dangerously close and blast the planet Earth with amounts of radiation that are just going to zot away whatever is left of our atmosphere. So much radiation, so much light from the sun is going to blast our planet that our atmosphere is going to be toast.

It is not a good future, but we have had a good 4.6 billion year run.
Fraser: Thatâ€™s true. Thatâ€™s true. I think then, from what I understand, we are just far enough away that we probably wonâ€™t actually be consumed by the sun so then the Earth will just rotate the burned out white dwarf for hundreds of billions of years.
Pamela: Exactly. Our planet isnâ€™t likely to get destroyed, at least through any of the processes we currently understand. It is just life that is going to be destroyed.
Fraser: But I wonder though if our planet is going to continue to cool down it will still be a source of heat so all of the underground microbes will probably still be perfectly happy.
Pamela: Exactly. Exactly.
Fraser: Yeah thatâ€™s funny. All right, well that was great. So now we have covered the Earth, so next week we will proceed with the planetary excursion and we will do Mars, which I think is going to be a monster show because there is a lot to talk about there.
This transcript is not an exact match to the audio file. It has been edited for clarity. Transcription and editing by Cindy Leonard.

## South Pole

Encyclopedic entry. The South Pole is the southernmost point on the Earth. It is located on Antarctica, one of the Earth's seven continents.

Earth Science, Geology, Geography, Physical Geography, Social Studies, World History

The South Pole is the southernmost point on the Earth. It is the precise point of the southern intersection of the Earth's axis and the Earth's surface.

From the South Pole, all directions are north. Its latitude is 90 degrees south, and all lines of longitude meet there (as well as at the North Pole, on the opposite end of the Earth).

The South Pole is located on Antarctica, one of the Earth's seven continents. Although land at the South Pole is only about a hundred meters above sea level, the ice sheet above it is roughly 2,700 meters (9,000 feet) thick. This elevation makes the South Pole much colder than the North Pole, which sits in the middle of the Arctic Ocean. In fact, the warmest temperature ever recorded at the South Pole was a freezing -12.3 degrees Celsius (9.9 degrees Fahrenheit).

The South Pole is close to the coldest place on Earth. The coldest temperature recorded at the South Pole, -82.8 degrees Celsius (-117.0 degrees Fahrenheit), is still warmer than the coldest temperature ever recorded, -89.2 degrees Celsius (-128.6 degrees Fahrenheit). That temperature was recorded at the Russian Vostok Research Station, about 1,300 kilometers (808 miles) away.

Because the Earth rotates on a tilted axis as it revolves around the sun, sunlight is experienced in extremes at the poles. In fact, the South Pole experiences only one sunrise (at the September equinox) and one sunset (at the March equinox) every year. From the South Pole, the sun is always above the horizon in the summer and below the horizon in the winter. This means the region experiences up to 24 hours of sunlight in the summer and 24 hours of darkness in the winter.

Due to plate tectonics, the exact location of the South Pole is constantly moving. Plate tectonics is the process of large slabs of Earth's crust moving slowly around the planet, bumping into and pulling apart from one another.

Over billions of years, Earth's continents have shifted together and rifted apart. Millions of years ago, land that today is the east coast of South America was at the South Pole. Today, the ice sheet above the South Pole drifts about 10 meters (33 feet) every year.

Amundsen&ndashScott South Pole Station

Compared to the North Pole, the South Pole is relatively easy to travel to and study. The North Pole is in the middle of the Arctic Ocean, while the South Pole is on a stable piece of land.

The United States has had scientists working at Amundsen&ndashScott South Pole Station since 1956. Between 50 and 200 scientists and support staff live at the this research station at any given time. The station itself does not sit on the ground or ice sheet. It is able to adjust its elevation, to prevent it from being buried in snow, which accumulates at a rate of about 20 centimeters (8 inches) every year, and does not melt.

In the winter, the Amundsen&ndashScott South Pole Station is completely self-sufficient. The dark sky, freezing temperatures, and gale-force winds prevent most supplies from being flown or trekked in. All food, medical supplies, and other material must be secured before the long Antarctic winter. The station's energy is provided by three enormous generators that run on jet fuel.

In winter, stores of food are supplemented by the Amundsen&ndashScott South Pole Station's greenhouse. Vegetables in the greenhouse are grown with hydroponics, in a nutrient solution instead of soil.

Some of the earliest discoveries made at South Pole research stations helped support the theory of continental drift, the idea that continents rift apart and shift together. Rock samples collected near the South Pole and throughout Antarctica match samples dated to the same time period collected at tropical latitudes. Geologists conclude that the samples formed at the same time and the same place, and were torn apart over millions of years, as the Earth split into different continents.

Today, the Amundsen&ndashScott South Pole Station is host to a wide variety of research. The relatively undisturbed ice sheet maintains a pristine record of snowfalls, air quality, and weather patterns. Ice cores provide data for glaciologists, climatologists, and meteorologists, as well as scientists tracking patterns in climate change.

The South Pole has low temperatures and humidity and high elevation, making it an outstanding place to study astronomy and astrophysics. The South Pole Telescope studies low-frequency radiation, such as microwaves and radio waves. The South Pole Telescope is one of the instruments designed measure the cosmic microwave background (CMB)&ndashfaint, diffuse radiation left over from the Big Bang.

Astrophysicists also search for tiny particles called neutrinos at the South Pole. Neutrinos interact very, very weakly with all other matter. Neutrino detectors therefore must be very large to detect a measurable number of the particles. The Amundsen&ndashScott South Pole Station's IceCube Neutrino Detector has more than 80 "strings" of sensors reaching as deep as 2,450 meters (8,038 feet) beneath the ice. It is the largest neutrino detector in the world.

Ecosystems at the South Pole

Although the Antarctic coast is teeming with marine life, few biologists conduct research at the Amundsen&ndashScott South Pole Station. The habitat is far too harsh for most organisms to survive.

In fact, the South Pole sits in the middle of the largest, coldest, driest, and windiest desert on Earth. More temperate parts of this desert (called either East Antarctica or Maudlandia) support native flora such as moss and lichen, and organisms such as mites and midges. The South Pole itself has no native plant or animal life at all. Sometimes, however, seabirds such as skuas can be spotted if they are blown off-course.

Exploration

The early 20th century's "Race to the Pole" stands as a symbol of the harrowing nature of polar exploration.

European and American explorers had attempted to reach the South Pole since British Capt. Robert Falcon Scott's expedition of 1904. Scott, along with fellow Antarctic explorers Ernest Shackleton and Edward Wilson, came within 660 kilometers (410 miles) of the pole, but turned back due to weather and inadequate supplies.

Shackleton and Scott were determined to reach the pole. Scott worked with scientists, intent on using the best techniques to gather data and collect samples.

Shackleton also conducted scientific surveys, although his expeditions were more narrowly focused on reaching the South Pole. He came within 160 kilometers (100 miles) of the pole in 1907, but again had to turn back due to weather.

Scott gathered public support and public funding for his 1910 Terra Nova expedition. He secured provisions and scientific equipment. In addition to the sailors and scientists on his team, the Terra Nova expedition also included tourists&mdashguests who helped finance the voyage in exchange for taking part in it.

On the way to Antarctica, the Terra Nova expedition stopped in Australia to take on final supplies. Here, Scott received a surprising telegram from Norwegian explorer Roald Amundsen: "Beg leave to inform you Fram [Amundsen's ship] proceeding Antarctic."

Amundsen was apparently racing for the pole, ahead of Scott, but had kept all preparation secret. His initial ambition, to be the first to reach the North Pole, had been thwarted by American explorers Frederick Cook and Robert Peary, both of whom claimed to reach the North Pole first. (Both claims are now disputed, and Amundsen's flight over the North Pole is generally recognized as the first verified journey there.)

The Terra Nova and Fram expeditions arrived in Antarctica about the same time, in the middle of the Antarctic summer (January). They set up base camps about 640 kilometers (400 miles) apart. As they proceeded south, both expeditions established resupply depots with supplies for their return journey. While Scott's team stuck to a route forged by Shackleton years earlier, Amundsen took a new route.

Scott proceeded with scientific and expeditionary equipment hauled by dogs, ponies, and motor sledges. The motorized equipment soon broke down, and the ponies could not adapt to the harsh Antarctic climate. Even the sled dogs became weary. All the ponies died, and most members of the expedition turned back. Only four men from the Terra Nova expedition (including Scott's friend Wilson) proceeded with Scott to the pole.

Amundsen traveled by dog sled, with a team of explorers, skiers, and mushers. The foresight and navigation paid off: Amundsen reached the pole in December 1911. He called the camp Polheim, and the entire Fram expedition successfully returned to their resupply depots, ship, and Norway.

More than a month later, Scott reached the South Pole, only to be met by Amundsen's camp&mdashhe had left a tent, equipment, and supplies for Scott, as well as a note for the King of Norway to be delivered if the Fram expedition failed to make it back.

Disheartened, Scott's team slowly headed back north. They faced colder temperatures and harsher weather than Amundsen's team. They had fewer supplies. Suffering from hunger, hypothermia, and frostbite, all members of Scott's South Pole expedition died fewer than 18 kilometers (11 miles) from a resupply depot.

American explorer Richard E. Byrd became the first person to fly over the South Pole, in 1926, and the Amundsen&ndashScott South Pole Station was established thirty years later.

However, the next overland expedition to the South Pole was not made until 1958, more than 40 years after Amundsen and Scott's deadly race. The 1958 expedition was led by legendary New Zealand mountaineer Sir Edmund Hillary, who had become the first person to scale Mount Everest in 1953.

Transportation to the South Pole

Almost all scientists and support personnel, as well as supplies, are flown in to the South Pole. Hardy military aircraft usually fly from McMurdo Station, an American facility on the Antarctic coast and the most populated area on the continent. The extreme and unpredictable weather around the pole can often delay flights.

In 2009, the U.S. completed construction of the South Pole Traverse. Also called the McMurdo-South Pole Highway, this stretch of unpaved road runs more than 1,600 kilometers (995 miles) over the Antarctic ice sheet, from McMurdo Station to the Amundsen&ndashScott South Pole Station. It takes about 40 days for supplies to reach the pole from McMurdo, but the route is far more reliable and inexpensive than air flights. The highway can also supply much heavier equipment (such as that needed by the South Pole's astrophysics laboratories) than aircraft.

Resources and Territorial Claims

The entire continent of Antarctica has no official political boundaries, although many nations and territories claim land there. The South Pole is claimed by seven nations: Argentina, Australia, Chile, France, New Zealand, and the United Kingdom.

Photograph by Calee Allen, MyShot

No Time at the Poles
Time is calculated using longitude. For instance, when the sun seems directly overhead, the local time is about noon. However, all lines of longitude meet at the poles, and the sun is only overhead twice a year (at the equinoxes.) For this reason, scientists and explorers at the poles record time-related data using whatever time zone they want.

Cold and Lonely Highway
The South Pole Traverse is not paved. The highway was created by filling in deep crevasses in the Antarctic ice sheet. The only vehicles on the highway are specialized tractors equipped with specialized towing sleds.

The few "winter-overs" at Amundsen-Scott South Pole Station have an annual tradition. After the last supply plane has left the facility (not to return for six months), they watch two movies: The Thing (about a parasitic alien being terrorizing an Antarctic research facility) and The Shining (about a caretaker isolated at a remote hotel in the winter).

## The Sun's Travels and Why Fall is Nigh

Wednesday, Sept. 22 marks what scientists call the fall equinox in the Northern Hemisphere, when night and day are of equal length and cooler weather is on the way -- if it hasn't already arrived.

But what's behind the shift?

A year-long series of pictures by Greek photographer Anthony Ayiomamitis helps put the equinox into perspective, while also illustrating why we have seasons.

The image shows the Sun's position in the sky at the same time each day, every week or so, during a full year. The figure-8 pattern created by the Sun's apparent annual movement is called an analemma.

The high point comes during summer when the days are long, and the low point in winter when the Sun remains frustratingly low on the horizon, days are short, and less radiation is available to warm the ocean, air and land.

Ayiomamitis explains where the Sun is in his picture as we reach the fall equinox:

"The crossover point between the smaller upper loop and the larger lower loop is Aug. 30," he explained. "We are now between the third and fourth solar disks below and to the right of the crossover point."

The Sun appears to move around so much because Earth is tilted on its rotational axis, by about 23.5 degrees. Earth's North Pole always points in roughly the same direction in relation to the plane of the solar system. But as the planet orbits the Sun (once each year) a major change occurs.

In the Northern Hemisphere's summer, the North Pole leans toward the Sun, causing the Sun to be higher in our sky and spreading warmth copiously. In winter, the pole leans away from the Sun and things get chilly (while those south of the equator are treated to longer days). To visualize this, imagine pointing toward someone who is at the center of a room, then walk around to the other side of the room without changing your arm's pointing position in relation to your entire city -- you'll then be pointing away from the person.

The analemma's figure-8 is not symmetrical. That's because Earth's 365-day orbit is not a perfect circle. We are closer to the Sun in January, and this causes Earth to move faster compared to summertime, making the bottom loop of the analemma -- the winter portion -- larger.

(Being slightly closer to the Sun in winter does not provide enough extra warmth to overcome seasonal effects caused by the planet's tilt, however. More about that here.)

For his image, Ayiomamitis patiently made 47 exposures of the Sun between Jan. 7 and Dec. 20 last year, all on one frame of film. Then a second picture that included the foreground -- the temple Hephaisteion, in Athens -- was taken and added to the first.

On his web site, Ayiomamitis has more views of the analemma and details about how he created the photographs.

## What caused all this weirdness?

Interest in these unexpected jolts is about more than mapping. The dance of Earth's magnetic field lines presents one of the few windows scientists have to processes that happen thousands of miles below your feet.

At the 2018 American Geophysical Union fall meeting, Livermore presented what he calls a magnetic field “tug-of-war” that may offer an explanation for the recent odd behavior. The north magnetic pole seems to be controlled by two patches of magnetic field, he explains, one under northern Canada and one under Siberia. Historically, the one under northern Canada seems to have been stronger, keeping the magnetic pole in its clutches. But recently, that seems to have changed.

“The Siberian patch looks like it's winning the battle,” he says. “It's sort of pulling the magnetic field all the way across to its side of the geographic pole.”