Astronomy

How can a mirror see things that the naked eye can't?

How can a mirror see things that the naked eye can't?


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How does a mirror pick up light from vast distances away? And, if that light can reach a mirror, why can't we see that light?


Your eye has two functional parts: a lens (that is about ¼cm²) and a light-sensitive surface (the retina) that is covered in rod-cells that detect light. It takes about 10 photons arriving at about the same time (0.1sec) for a rod to react to the light and send a signal to the brain.

This means that, unless about 400 photons arrive from a star onto every square centimetre then there isn't enough light to see the star, even under ideal conditions. In practice, many more photons are needed for your brain to be able to interpret the signal from your eye as a point of light.

In contrast the mirror of a telescope is much larger. A small amateur telescope could have a mirror that has an area 1000 times larger than the lens of your eye. This means that a star can be 1000 times dimmer, but still be visible when you look at it in the telescope. Large, professional, telescopes have mirrors that are millions of times greater than the area of an eye.

Moreover a telescope can be fitted with a camera, and film (or digital sensors) that are both more sensitive to light than your retina and can integrate the light arriving over a long period of time. If you make a long exposure, of several minutes, or even hours, then even dimmer objects will become visible. This can increase the sensitivity by a factor of many thousand again.

The combination of the large light gathering area of the mirror, with the sensitivity and long exposures make possible to "see" things using the mirror of a telescope that can't be seen with the naked eye.


What I Learned Writing ‘Night Sky with the Naked Eye’

The author enjoys a pretty display of the northern lights on October 23, 2016 under a starry sky. His new book, “Night Sky with the Naked Eye,” explores all the amazing things you can see in the sky without special equipment including satellites, planets, meteor showers and of course, the aurora.

My book Night Sky with the Naked Eye publishes today. It would have never seen the light of day much less ever been conceived were it not for Fraser Cain, publisher of Universe Today, and Nancy Atkinson, an editor and writer for the same. Several years ago, Nancy invited me to write for UT. I hopped at the chance. Before her contact, I’d been writing a daily blog on astronomy called Astro Bob (and still do).

Fast forward to last summer when I got an email from Nancy saying Page Street Publishing had contacted her about writing a book about space missions. The publisher also wanted a book about night sky observing without fancy equipment for which she recommended me. Me? I felt like the luckiest guy on the planet!

Book writing proceeds in many stages. First, the table of contents had to be prepared and approved. Then followed a sample chapter. The publisher chose the one on artificial satellites, which I wrote in about a week. The tone was right, but he asked for changes in the organization, which I dutifully made. By November, a contract followed and the project was underway with a first draft due to my editor in about 10 weeks.

Writing is hard work. But it’s a special place all writers come back to again and again. We can’t help but keep trying to find just the right words to capture a concept or emotion. And when we do, a quiet pleasure flows down the spine like warmth creeping into cold fingers splayed in front of a fire. Not that these moments always come easily. Writer Colson Whitehead describes the experience of writing as “crawling through glass.” I would soon become well-acquainted with that feeling, too.

Nancy wrote her book Incredible Stories from Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos at nearly the same time. We were grateful for each other’s support, and it was a kick to follow her progress as well as bounce ideas around. With a tight deadline in front of me, I set to work immediately, taking more than two weeks of vacation from my regular job to make sure the draft was done on time. No way was I going to compromise an opportunity of a lifetime.

Maybe you’ve thought of writing a book, starting a blog or hope one day to write for Universe Today or another online astronomy site. There’s plenty of good advice for writers out there. I’ll share what worked for me.

#1: Put your butt in the chair and keep it in the chair. My wife reminded me of this often, adding that the book wasn’t going to write itself. Temptations are everywhere. Answering the phone, making another cup of tea, staring out the window and my favorite, shoveling the driveway. I had the cleanest driveway in the neighborhood. Even an inch of new snow was enough to grab the shovel and happily scrape down to the gravel. So yes, I did occasionally get out of the chair, but many times it did me good, freeing up the brain to see more clearly into a topic. Or dream up a fitting photo or illustration.

Creativity comes at odd little moments. It can flow while tapping away in front of a glowing screen or sneak into consciousness when you’re bending down to feed the dog. So a mix of activities seemed the best but with extra emphasis on staying put. I rarely hiked last winter and kept my walks in the neighborhood brief. Instead of observing at night, I wrote or gathered photos. By January, I joked to my friends that I’d voluntarily put myself under house arrest.

#2: Spill your guts, worry about the details later. It’s incredibly tempting when writing to continuously edit one’s work, going back over every sentence to make each “perfect”. This is a muse-killer. Though difficult to stick to, once you let your thoughts flow onto paper without worrying about spelling, clauses and the whole lot of burdensome rules, you’ll become a wild horse running free on the prairie. Let it out, let it out and worry about the commas later. I don’t play a musical instrument, but free-flow writing — just getting the ideas out — must feel something like riffing on a jazz melody.

#3: When stuck, move on to another topic, take a walk, listen to music. Struggling to describe an important concept or connecting your thoughts in a way that flows on the page can drive you nuts, even bring you to tears. Sure, you can keep beating on the idea like a madman hammering on a bent nail, but why why torture yourself? A little distraction can be good. Move on to another part of the story or a different chapter or get up and take a short walk. Defocusing allows the ideas you’re having a tug-of-war with to come of their own accord.

To keep track of ideas, topics and the photos I’d need for the book, I kept a notebook filled to the gills with lists. Checkmarks indicate tasks accomplished. Credit: Bob King

As the February 1 deadline approached, time took on a physical dimension under the intense pressure to get everything done. I cut time into little blocks that when added up would get me to the finish line on the first draft. I made it just in time, shipped off my copy via e-mail, got in the car to go to work and turn up the music really LOUD. For a fews days I was on top of the world. Invincible.

My editor, Elizabeth, contacted me later with positive comments and then returned the manuscript with “developmental edits” or questions about descriptions and organization. We pitched the ever-refined draft back and forth over the next few months. Each time I read through the ten chapters and made both suggested changes and other refinements. I also added photos during this stage and worked via e-mail with the layout staff to place the best images and graphics at the best places in the text. I shot more images and requested photos from talented astrophotographers, prepared the acknowledgments and sought our recommendations from respected scientists and writers.

This diagram from the book uses the human face to illustrate how changing lighting angles causes the phases of the moon. Credit: Bob King

The editors at Page Street were quite generous with photo usage, a joy for me because that’s what I do for a living. I’ve been a photographer and photo editor at the Duluth News Tribune in Duluth, Minn. for many years. My favorite subjects are people, but I slip in an aurora or eclipse now and again. And that’s the irony. I never saw myself as a writer.

Like many, I started by keeping a journal of my observations through the telescope and reflections about the night sky. The Astro Bob blog took that a step further and writing for Universe Today and Sky & Telescope let me find my voice. So I maybe I have a voice, and I like to think I can be a helpful guide at your side, but writer? That still seems too lofty a term to describe what I do. But here we are.

After several edits including the final one, when I was sent a thick stack of low-res black and white pages of the book to mark up and return, I rested briefly before beginning the final phase: publicity. This is the weird part, where you tell everyone what a nice book you’ve written and how it would make a great Christmas gift for that budding astronomer in the family. When I held the first copy in my hands I couldn’t believe that all those hours of work at the computer became a physical object, a beautiful one even.

This map from the book shows Saturn’s location around the time of opposition through 2021. Credit: Bob King, Source: Stellarium

I’m biased of course, but I think both beginning and amateur astronomers will find the book useful. It includes lots of suggested activities – set off in separate boxes – to encourage you to get out under the stars. I make regular mention of the Web and phone apps as ways to become more familiar with the constellations, learn of newly-discovered bright comets and even find a dark sky.

Besides the easy naked eye topics like how to find the brightest constellations or see the best meteor showers of the year, the book offers visual challenges. Have you ever seen craters on the Moon without optical aid or the midnight glow of the gegenschein? You’ll find out how in my book. As a photographer, I’ve included tips on how to focus a digital camera and use it to photograph the aurora or a space station pass.

I’d be willing to bet that most books aren’t as complete as their authors would hope. I had to cut precious photos, graphics, 3 years of a sky calendar and other bits and pieces from mine. Ouch! To this day, I’m still thinking of ways to improve it with a fresh photo, new diagram or change of wording. Now it’s your turn to be the judge.

The zodiacal light punctuated by the planet Jupiter towers over northern Wisconsin along Lake Superior near Duluth, Minn. this morning (Nov. 8). The book describes nighttime lights such as the zodiacal, gegenschein, airglow in addition to lunar halo and corona phenomena. Credit: Bob King

Throughout, Nancy and I rooted for one another and shared our ups and downs. Incredible Stories was to publish within a week of Night Sky, but a type corruption error discovered in several chapters put the book on hold. Her new publication date is December 20, and I encourage you to pre-order a copy, so it arrives in time for Christmas. Order a copy of my book also, and I promise the two of us will keep you company on those long winter nights ahead.

Can I share one final tip? Once you’ve found your passion, say ‘yes’ to every opportunity that furthers it. You’ll be amazed at the places that one word will take you to.

*** To order a copy of Night Sky with the Naked Eye just click an icon to go to the site of your choice — Amazon, Barnes & Noble or Indiebound. It’s currently available at the first two outlets for a very nice discount. It should also be at your local B&N bookstore. And don’t forget to vote today!


Are you a beginner? We can help . read on!

There are so many options to choose from when you first take up amateur astronomy. We are here to help, whether you want equipment, a training course, or just some friendly advice. One doesn't need any equipment to start enjoying the night sky. On a clear night, it can be fun, and educational, to get a basic orientation finding the north star (Polaris), identifying some constellations and differentiating a planet from a star are great first steps! With your naked eye, you can see Jupiter, Venus, Mars, Saturn, the Milky Way, and even satellites hurtling by! A telescope, and to some extent binoculars, can reveal still more amazing celestial features. Stop by the store and talk to us today. We can help you understand the nuances of observing planets versus "deep sky objects" (and vice-versa). We'd be happy to clearly explain magnification, aperture and other astronomy vocabulary.


Ask Ethan: Why Can't I See Mercury Without A Telescope?

The eight planets of our Solar System and our Sun, to scale in size but not in terms of orbital . [+] distances. Mercury is the most difficult naked-eye planet to see.

Wikimedia Commons user WP

Since ancient times, humans have known of five planets -- or "wandering stars" -- in the sky: Mercury, Venus, Mars, Jupiter and Saturn. Each of them appears to move against the backdrop of stars from night-to-night, rather than staying in the same fixed position like the other points of light do. But while Venus, Mars, Jupiter and Saturn are all easily visible to the naked eye, most of us have never even seen Mercury. This is thoroughly dissatisfying to Erik Arneson, who wants to fix that:

I have been sitting on the coast watching the sun set through the thinnest sliver of clear sky on the horizon. I'm struggling with a question: how can one see Mercury with the naked eye? I know it's possible, but how can I observe it enough to know it's a "wandering star"? It's the only classical planet I've never seen. Help!

Mercury is by far the most difficult naked eye planet to see, and there's a very good reason why.

When looking at an interior planet, it will never appear to 'wander' too far from the Sun. Because . [+] of the significant orbital differences between Mercury and Earth, Mercury never appears more distant from the Sun than 28 degrees.

Wikimedia Commons user Wmheric

Mercury, unlike the other planets, never appears very far away from the horizon in the night sky. From Earth's perspective, that's because Mercury is the closest planet in its orbit with respect to the Sun. That on its own wouldn't be such a big deal the problem is that we're so much farther out than Mercury is! When Mercury is at its maximum distance (aphelion) from the Sun, it's actually 70 million kilometers away from it, or 47% of the typical Earth-Sun distance. Unfortunately, this means even in its ideal configuration, Mercury is only 28° away from the Sun as seen from Earth.

The orbits, to scale, of the inner worlds of our Solar System. Mercury is quite difficult to see . [+] from Earth due to the fact that it's never well-separated from the Sun.

That ideal configuration, by the way, almost never occurs. Mercury's orbit around the Sun is quite elliptical, and when it's at its closest distance (perihelion) from the Sun, it's only 18° away from the Sun in its ideal configuration. Most of the time, of course, Mercury isn't in its ideal configuration, known as maximum elongation. Most of the time, it's closer to the Sun than that, and this poses a problem for professional and amateur astronomers everywhere.

In the pre-dawn skies from New South Wales, Australia, Mike Salway was able to photograph the 2009 . [+] alignment of the Moon, Mercury (top), Jupiter and Mars. Competition with the Sun in order to view Mercury is usually unavoidable.

The reason is the simplest one of all: astronomical viewing of most objects is practically impossible during the day. In order to see the overwhelming majority of astronomical objects, you not only need for the Sun to set, you need for the sky to get dark. The sky reaches total darkness when the Sun drops about 18 ° below the horizon, but you can see Mercury when the Sun's only about 6° below the horizon under ideal conditions. This is because Mercury, during its maximum elongation, is actually quite bright: about as bright as Canopus, the second-brightest star in the entire sky. When the stars begin to come out, so does Mercury.

It only happens once every 11 years, but occasionally, all five naked-eye planets are visible at . [+] once. Mercury is always the toughest to spot.

But this combination of Mercury being close to the Sun and the Sun needing to drop a few degrees below the horizon is a big problem for many would-be Mercury observers across the world. The problem, you see, is that Mercury, the Sun and the Earth all orbit in roughly the same plane: the ecliptic. And the Sun doesn't simply rise in the east, travel straight overhead at the zenith, and then set in the west. Rather, it travels in a curved path, and that curved path gets more severe the higher your latitude gets.

The Sun's apparent path through the sky on the solstice is vastly different at 20 degrees latitude . [+] (left) versus 70 degrees latitude (right).

Wikimedia Commons user Tauʻolunga

For those of you above the 45th parallel (in either hemisphere), that's a big enough problem that you're pretty much destined to never see Mercury, even if you have a clear view of the horizon and a clear evening/morning sky. If you were closer to the equator, though, viewing Mercury would be a snap. In fact, those of you who live close to the equator -- ideally, about 10-15° south of it -- will have a wonderful chance to do exactly what Erik is asking about during the final week of July and the first week of August this year.

High latitudes experience the Sun passing through the sky, including rising and setting, at a . [+] significant angle, while near the equator, the Sun rises and sets nearly straight up and down.

Mercury reaches a maximum elongation of 27.2° on July 30th, where it will be visible in the evening sky. From 10-15° south latitude, the Sun will appear to set almost perfectly vertically, meaning that when the Sun reaches 18° below the horizon and we have true darkness, Mercury will still be 9° above the horizon. If you watch it from approximately July 20th to August 9th, you'll see Mercury wander, providing great evidence that it is, in fact, a planet.

The best way to see Mercury is from a large telescope, as dozens of stacked images (left, 1998, and . [+] center, 2007) in the infrared can reconstruct, or to actually go to Mercury and image it directly (right), as the Messenger mission did in 2009.

R. Dantowitz / S. Teare / M. Kozubal

So how can you ever see it if you live closer to the poles than the equator? Well, those of you who'll be on the west coast of the United States on August 21st will have your opportunity to go see a total solar eclipse from right at the 45th parallel! The skies get dark during the day a little after 10 AM depending on where you are, and the bright star Regulus will be very close to the Sun at that time, and visible during the day during totality. Just below it, closer to the horizon, will be Mercury, while above it, farther from the horizon, will be Mars. It's the perfect time to see them all.

A simulated picture of the sky as it might appear during the upcoming total solar eclipse during . [+] August 21st. The image is reflective of how the sky might appear near Salem, OR, at the moment of totality.

The reason Mercury is so elusive for so many of us is mostly because of our latitude on this world. How can you see something when the way the Sun orbits the Earth prevents the sky from darkening until the planet you're looking for is below the horizon? There are going to be times where you can see it better than others, but your best bet is to get closer to the equator, and to look to the west after sunset when Mercury's at maximum eastern elongation, or to the east before sunrise when Mercury's at maximum western elongation. You have to plan ahead, especially when the Sun is in the way, and that doesn't just extend to seeing Mercury from Earth.

The Hubble Space Telescope, as imaged during the last and final servicing mission.

The Hubble Space Telescope is the most powerful observatory ever launched into space. From low Earth orbit, it's given us our best views of all the worlds in our Solar System short of actually traveling across the great astronomical distances. But there's a world Hubble has never viewed: Mercury. The reason? Its close proximity to the Sun carries with it a risk: if you accidentally let direct sunlight into your telescope mirror, you'll fry the optical systems. Even with more than 20° to play with, the administrators who assign telescope time have never approved a Hubble mission to view Mercury. or even Venus, owing to this risk.

So think about it this way: just by traveling close to the equator at the right time in Mercury's orbit, you can not only view the innermost planet in our Solar System and watch it wander, you can do what even humanity's greatest telescope won't.

On January 1st, 2018, Mercury reaches maximum western elongation. It will be the best opportunity to . [+] view it from high northern latitudes for some time.

And if you're absolutely hellbent on trying to see Mercury from a high northern latitude without budging, here's your best attempt: between the hours of 7:00-7:15 AM on January 1st, 2018, just before sunrise. Look to the east, where Mars and Jupiter will be close together, and follow the line they make back towards the horizon, close to the soon-to-be-rising Sun. If you have a clear eastern horizon, you just might see a single point of light poking out between Jupiter and the horizon that will be Mercury for you. But try taking a trip closer to the equator if you can it's the easiest solution of all!


Now Appearing

My quiz books How Many Moons Does the Earth Have? and What Colour is the Sun? are all about asking science questions with interesting or intriguing answers, so I was delighted when a reader, Simon Bartlett, asked about how realistic one of my answers was.

The question here (from How Many Moons) was 'What is the furthest you can see with the naked eye?' The traditional answer to this is to point out that you can see at least 21 miles (33 kilometres) across the English channel, and it's said that you can see a candle on a truly dark night about 10 miles (16 kilometres) away. However, I wanted to challenge this by pointing out that you can see the Andromeda galaxy with the naked eye (assuming a dark night and good eyesight), and that's around 2.5 million light years. So, bearing in mind this is usually the standard marker for maximum distance naked eye astronomy, I plumped for that. However, Simon felt this should be considered a bit further:

In reality neither of these questions I am supposed to have addressed is ideal. The figure I give for the Andromeda galaxy is a good default maximum as it’s the most distant object you can see with the naked eye under normal conditions - and that, in effect, delivers the furthest you can see. However, in extraordinary circumstances - when a big enough supernova is at its brightest, for example - you could see further still. Even then, though, there is going to be a limit to the range, as the power drops off with the square of the distance away, so you would need an exponential increase in brightness for an object to still be visible. The brightest known supernova to date, ASASSN󈝻lh (now possibly not a supernova at all) is described as having about 20 times the output of the Milky Way - which for our purposes will do as an order of magnitude comparison with the brightness of the Andromeda galaxy. This means you could push back the distance by a factor of around 4.5 and still see an object of this brightness with the naked eye - so we’re talking about maybe 11 million light years. There are brighter things than supernovas, notably quasars, but a lot of their output does not reach us in the visible spectrum - and they are also immensely distant, so they aren’t going to be seen with the naked eye. The brightest detected quasar, 3C273 is surprisingly bright given it's about 2 billion light years away, but would apparently need an 8 inch telescope to see it - not exactly naked eye stuff.

So my answer certainly wasn't wrong - it still makes sense as one answer to a 'most distant naked eye sighting' - but there's more to be got from that question.


How can a mirror see things that the naked eye can't? - Astronomy


A table of naked-eye astronomical data compiled by the Mayans (the "Dresden Codex")

E arly peoples knew the sky well and made many observations with their naked eyes. Each group had its own myths about the things in the sky. Their "cosmologies" were not drawn from reasoning about what they saw, but were stories about a moral universe. Nomads in the Sahara and tribal peoples in the American Southwest used stones to mark important celestial events like the summer solstice (the day the Sun ceases to climb higher at each noon). When people began to depend on agriculture, they needed to know the exact course of the seasons to help them decide when to plant and harvest. Ancient Egyptians, Celts, Mayans and others built colossal stone structures, precisely aligned to the seasonal risings and settings of the Sun, Moon, planets, and some bright stars.

Early astronomers used many kinds of instruments to study the heavens. All were basically tools for measuring or calculating the positions of objects in the sky. With them astronomers mapped the stars and made tables to predict the future positions of the Sun, Moon, and planets. This knowledge was important, for the sky served as a clock, a calendar, and a navigational aid to help seafarers find their way. It was used by priests to set the time for religious observances and by astrologers to cast horoscopes.

If the planets were gods, did they not influence, or even predict, human affairs? This idea gave rise to astrology. In the futile hope of turning their fantasies into a reliable science, priests and would-be prophets tracked motions in the heavens with the greatest possible precision. Hopes for a sort of technology to control the future thus became a main inspiration for the first observatories and the first star maps (more on astrology
here ).


Astronomers using an astrolabe (center-right), a quadrant (below), and and other instruments at the Istanbul Observatory. Built
in 1577, it was soon torn down under suspicion of impious astrological investigations.

The ancient Greeks learned to make precise instruments, crowned by the ingenious astrolabe. This hand-held device had a moveable arm to measure the angle of a bright star above the horizon — the star's "altitude." Rotating a metal map of stars to match engraved curves, the user could determine time and direction, locate stars in the sky, determine when the sun would rise or set, and make other calculations. Astrolabes reached their standard configuration by the fourth century, having been first developed in the first or second century near the Egyptian city of Alexandria.

The example shown here is Islamic and dates from the 11 th century. Astrolabes were especially important to Muslims who used them to determine the proper hours for prayer and the direction of Mecca. This astrolabe has several interchangeable plates, each engraved with the celestial coordinates for a different latitude. The pointers on the top plate indicate the positions of twenty-two bright stars. The top plate can rotate to show where those stars will appear at different times or dates, much like a modern paper or plastic star finder. The instrument could also be used to predict when the Sun or certain bright stars would rise or set on any date.


Modern depiction of the observatory Al-Tusi built at Maragha, Persia in 1258. Funded partly by religious endowments, it attracted scientists from as far as Spain and China.

I slamic astronomers made careful observations to improve Ptolemy's planetary and stellar positions. Notable observatories include those at Maragha, in north-west Persia (Iran), constructed in 1259 and staffed with renowned astronomers who came from as far as China and Spain, and at Samarkand in central Asia, built around 1420. The bigger such a structure was, the more accurately an observer could measure the positions of planets and stars. Princes supported such works partly because patronage of arts and sciences reflected glory upon themselves, and partly for more accurate astrology, which was not then clearly separated from genuine science.

MORE naked eye instruments from the Smithsonian


This medieval German quadrant could be used for navigation or as a sundial.

T he earliest devices for "sighting the stars" were crude sticks. Seamen improved these, arriving at a quarter-circle ("quadrant") marked off in degrees, with a sighting arm to measure a star's altitude. Eventually the quadrant was replaced by the sextant (named after one-sixth of a circle, it is actually one-twelfth, doubled with the aid of a mirror). A sextant was the inseparable companion of every navigator until the invention of electronic positioning systems in the late 20th century. Astronomers also used quadrants to map the positions of stars and planets.

The instrument in the picture is a rare example of especially ingenious medieval European instrument-making (ca. 1325 AD). The sighting arm rotates across a pattern made by folding the circular face of an astrolabe into quarters. The user can not only take star sights as with a quadrant, but make calculations as with a simple astrolabe. Essentially, the circular face of an astrolabe has been "folded over" twice to create a quarter-circle. This instrument could serve as a measuring tool and perform many of an astrolabe's calculation functions as well.


Full-scale replica of an armillary sphere built and used by Danish astronomer Tycho Brahe in the late 1500s.

A rmillary spheres large and small were used for centuries to study the sky and to teach about the celestial coordinate system, which astronomers used to locate objects in the sky. They were composed of rings (armillae) which represented the great circles of the celestial sphere.

Shown here is a full-scale replica of an armillary sphere built and used by Danish astronomer Tycho Brahe in the late 1500s. An observer would use its moveable rings and sighting devices to measure the position of a celestial object or differences between the positions of two objects.

T he larger the naked-eye instrument, the more precisely it could measure angles. A mural ("wall") quadrant was a large 90-degree arc attached to a north-south wall, with a sighting tool to measure the altitudes of stars and planets.

The most famous mural quadrant in Europe was built by Tycho Brahe in the 16th century as part of a grand observatory supported by the King of Denmark. In this picture, an observer at far right slides a sighting device to line up with a star that he sees through a slot in the opposite wall. At the moment the star is seen due south, he announces its altitude angle. An assistant below him announces the time, and another assistant, sitting at left, writes down the numbers. Behind the quadrant is a painting of Tycho and his assistants at work elsewhere in the observatory.

With his mural quadrant and other naked-eye instruments, Tycho recorded the positions of hundreds of stars and followed the motions of planets over decades. His mass of data was invaluable for later astronomers. Tycho's measurements were the most accurate ever made until telescopes came on the scene.


How can a mirror see things that the naked eye can't? - Astronomy

There are four that I can think of:

  • 1. The Milky Way. This is our galaxy. We're in it, so we can see it in all directions. You can see the largest concentration of stars in a band stretching across the sky. It is quite diffuse, so you need to be somewhere really dark to see it well. The centre is in the constellation of Sagittarius.
  • 2-3. The Magellanic Clouds (Large and Small) are two small(ish) galaxies which are being accreted by the Milky Way. You can only see them from the southern hemisphere.
  • 4. The Andromeda Galaxy (or M31) can be seen as a fuzzy patch in the constellation of Andromeda (again only if it is very dark out).

Galaxies are diffuse patches of light, so they are hard to see unless the sky is very dark. You can't even see the Milky Way from most cities, and Andromeda is even harder. It is possible though.

This page was last updated on January 28, 2019.

About the Author

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.


Why Is It So Difficult to See Pluto?

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New Horizons Spacecraft. Nasa

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Besides the stars, there are seven objects that everyone can see with the naked eye: the Sun, Mercury, Venus, the Moon, Mars, Jupiter, Saturn. (Well, don't look at the Sun, but you know it's there.) You might notice that the seven days of the week are named after these same objects. It's obvious that Monday is for the moon and Saturday is for Saturn, at least---less obvious that Tuesday is for Mars (unless you use another language, then it's obvious).

OK, but what about the other planets? What about Neptune and Uranus? Uranus was discovered in 1781 and Neptune was discovered in 1846 (both were discovered much later than the discovery of the Sun). And what about Pluto? Of course you know that Pluto isn't classified as a planet---but it will always still be Pluto. Pluto was discovered in 1930 by Clyde Tombaugh.

We don't know much about Pluto. We know its orbital path and we have an estimate for its mass. But what about surface features? What does it look like? It turns out that it's just damn difficult to see Pluto. Even with the Hubble Space Telescope, this is about the best we can do.

So, why is it so difficult to see Pluto? Three reasons.

Here is a simple experiment you can try. Take a red apple (or any colored object will do). Now bring your red apple into a room with no windows and no lights (no lights at all). In this dark room, what color does the apple appear? If you answer "you can't see that apple," I will give you partial credit. The correct answer is that the apple appears to be black. Of course the rest of the room is also black so that you can't really tell what part is the black room and what part is the red apple.

This simple experiment shows that in order for you to see this apple, you need light. Light from a lamp would reflect off the apple and then enter your eye. This is how we see most things---but not all. Some other things create their own light so that they are their own light source (like the Sun). However, Pluto is like the apple. In order to see it, you need light to reflect off the surface of the planetoid and enter your eye.

Where does this light come from that reflects off Pluto? It comes from the Sun. But there is a small problem. The Sun shines light that is essentially uniform in all directions. This means that you can think of light as an expanding sphere centered on the Sun. The light from the Sun is then spread over the surface area of this sphere. Since the area of a sphere is proportional to the square of the radius of the sphere, doubling the distance from the Sun decreases the intensity of light by a factor of 4.

Pluto is very far from the Sun. In fact it is about 30 to 50 times farther from the Sun than the Earth. So, there is significantly less light from the Sun at the location of Pluto. But wait! It gets worse. When the sunlight hits the surface of Pluto some of it is absorbed and some is reflected. Of the light that is reflected, it also expands outward from the surface of Pluto much like the Sun. By the time the light has gone from the Sun to Pluto to Earth, the reflected light intensity is just super small (not a scientific term).

If you look up the brightness for Pluto, it will be listed as an apparent magnitude of 13.64 to 16.3. What is apparent magnitude? This is an archaic system of reporting the brightness of stars and planets that was created by Greek astronomers a long time ago. The magnitude system breaks visible stars into 6 groups with magnitude 1 being the brightest and 6 being the faintest. Modern adjustments to the original classification says that each level of magnitude decreases the apparent brightness by a factor of 2.512. This means that a magnitude 1 star appears 100 times brighter than a magnitude 6. Note that Pluto is at BEST at magnitude 13.64. You just can't see this planetoid with the naked eye.

Is there a way to fix this brightness problem? Yes. The best way to create an image of very faint objects is to gather more light from that object. This can be accomplished with a larger diameter optical instrument like a telescope with a large mirror as the primary optical piece. Bigger telescopes are better.

You can probably do a simple experiment. Hopefully you have a pair of binoculars that you can use. If so, take them outside at night. First, look at some section of the sky where you can see some stars. Now look through the binoculars at the same section. You should be able to see many more stars with the binoculars than you could with just your eyes. Why? Because the lens of the binoculars are much larger than your pupils. This gathers more light so you can see dimmer objects.

There is one more problem, light pollution. Humans tend to have artificial lights on during the night time. These artificial lights illuminate the ground the sky as well. Light scatters off the air and makes it difficult to see dimmer stars. There are three solutions to light pollution. 1) Turn off the lights. 2) Move to a higher elevation with less air (like on a mountain top). 3) Move to where there is no air---like in space (Hubble Space Telescope).

Maybe you can see Pluto with your super awesome and huge telescope. Also, you are out in the middle of no where so that there's no light pollution. What next? Well, you probably want to see some details about the planet. This is where magnification comes into play. If you have used a pair of binoculars you know that when you look through them, things look bigger.

Actually, I'm not going to say anything else about magnification. You probably already have a good feeling for this and it usually isn't the problem.

If you make a tiny hole in a sheet of metal, light can pass through this hole and make a spot on a nearby screen. With a single light as the source, it might look like the spot on the screen is a perfect circle, but it's not. Light doesn't pass through openings in a clean manner but instead it is more fuzzy. This fuzziness is due to the diffraction of light.

Imagine a similar (but easier to visualize) situation. You are sitting on the beach watching the waves come in. Next you move to another location that has a breaker wall a little bit off shore. If this wall has an opening, the waves can pass through. And here you can see diffraction. The waves don't pass straight through, they bend as the pass through the opening. It would look something like this.


RedRock Astronomy

My friend and I were in Moab for a few days and wanted to do a stargazing tour. Unfortunately, our visit aligned with the dreaded moon-out. The moon’s light was too strong to see many of the features of the night sky. Moab Astronomy Tours with Crystal was doing a moon viewing tour that explores the moon and it’s features which I almost booked. However… Luckily the last night we were in town Moab Red Rock Astronomy with Alex was able to get a tour setup before the moonrise. The tour was happening just as the moon-out cycle was coming to an end. We confirmed the tour through email and received instructions from Alex to print out and bring with us.

There isn’t good cell phone reception in Moab, so be sure to print out the instructions before going. Also, Alex collects payment at the tour in cash, so maybe stop at the ATM prior to the tour.

On the evening of our tour, the tour met at a parking area on the edge of town. Once everyone had assembled in the parking lot, Alex stepped out of his vehicle to briefly say hello and explain that we would be following him to an area outside of town to do the viewing. The drive was about 20 minutes on the highway towards Dead Horse Point. The entire route is paved.

The tour site has an outhouse and decent sized parking area. Depending on the time of year your tour is, bring a blanket, warm clothes, snacks, water, etc. We did our tour in late March. Although we dressed warm and brought a blanket, it did get chilly and I found myself wishing I had worn a step-up in the warmth of the gear that I had on. Still, we had fortunately brought a blanket which helped. After getting to the site, you walk a very short distance (about 30 feet) to where Alex sets up the telescope. You are able to bring your backpacks with you to the telescope. There was no need for a flashlight as you are only walking a few feet outside the parking area. Alex provided folding chairs to sit in around the telescope so there is no need to bring those with you.

Alex himself is a bit of a character, but friendly and great with kids. He was always willing to answer questions or find something in the night sky that you specifically wanted to observe.

Our tour group was fairly small. There were two families with kids, myself, and my friend. Smaller groups would be ideal for this tour as it takes a bit of time to view the objects through the telescope. After things are setup, Alex gives a brief introduction. We explored the night sky with the use of the naked eye locating some of the features we could find. These included the big dipper, north star, passing satellites, and space junk streaking across the night sky. We got lucky and found the International Space Station which could be briefly seen. It was truly amazing to look up and see the stars with very little city light pollution. The countless stars seemed to shine so brightly! The brightest I had ever seen them.

Eventually, Alex locates several objects inside the telescope and the group took turns viewing these while Alex explained some details. Things we were able to observe included other galaxies and a nebula. Unfortunately, other planets were not in the correct position for us to view them. Still, we made some interesting observations and learned a few things along the way. Our tour lasted about 75-90 minutes once we got to the parking area. Depending on the time of year you do the tour, you might be getting back to Moab after the restaurants and grocery stores are closed. So pick up dinner before you head on the tour.

I think the tour might be a bit unexciting for younger children. However, pre-teens and older would all probably find the tour interesting. If nothing else, it was just great seeing the night sky with the stars shining so strongly.

If the tour sounds like it might not work for you, it’s completely fine to just head out to the desert and spend some time away from town observing the night sky. Stargazing can be fun even without a telescope. You’ll be surprised at what you can see after your eyes acclimate to the night.


How can a mirror see things that the naked eye can't? - Astronomy

Until recently, most of the advances in the non-magical area of astronomy were made by Muggles, and we witches and wizards learned about their findings second-hand. This lesson will be primarily devoted to the non-magical tools that have aided in these great discoveries, many of which are also used, or have been adapted to be used, by magical folk as well.

Telescopes

A telescope is an optical instrument that magnifies a distant object and makes it appear brighter. They are astronomy&rsquos most important tool and were used to discover Uranus, Neptune, and Pluto. With their aid, Muggle astronomers have discovered, and continue to discover, new asteroids, comets, stars and galaxies (collections of stars), moons, and even planets orbiting other stars. By examining the colour of light from distant galaxies with the 100-inch-wide Hooker telescope, then the biggest one in existence, an American astronomer Edwin Hubble was able to conclude that the universe is expanding, initiating the branch of astronomy called cosmology, which studies the origin and evolution of the universe. More information about Hubble can be found here . As you can see, the telescope is truly an invaluable tool.

The earliest telescopes had two lenses at opposite ends of a tube. At the far end of the tube is the light-gathering lens, called the objective lens. This lens is convex &ndash that is, thicker in the middle than at the edges &ndash like a magnifying glass and is called a positive lens. Distant objects seen through a magnifying glass on its own appear blurry. To make them appear sharp, you need another lens at the near end of the tube, called the eyepiece. In the earliest telescopes, the eyepiece was concave &ndash that is, thinner in the middle than at the edges &ndash and was called a negative lens. This was the design of the first Muggle telescope, invented by Hans Lippershey, a Dutch eyeglass maker, in 1608. It made distant objects look three times as big as with the naked eye. If you want to build a telescope of this kind, instructions can be found here .


Diagram of a telescope.
Source: here

Two years later, Galileo Galilei, a famous astronomer, improved on that design. He found that by making the objective lens less curved, he could improve the magnifying power from three to 20, making it a more useful astronomical tool. He used it to discover the four largest moons of Jupiter, which are therefore called the Galilean moons. He also discovered that Venus has phases like the Moon, confirming Copernicus&rsquos belief that the Earth revolves around the sun rather than the other way around (more on this later in the course). As a result, any telescope whose eyepiece is a negative lens is now called a Galilean telescope.

Galileo&rsquos telescope.
Source: here

One problem with the Galilean telescope is that it has a very narrow field of view, so you can only see a very small part of the sky with it. Johannes Kepler (more on him later in this lesson) found that if the eyepiece is also a positive lens, you can see much more of the sky. Everything you look at appears upside down, but astronomers don&rsquot care much about that because they can easily adjust to it therefore, this type of telescope is called an astronomical telescope. People who want to look at things on Earth, like navigators on ships, don&rsquot want either of those disadvantages, so they use what is called a terrestrial telescope. In that sort of telescope, the eyepiece has two positive lenses the one nearest your eye turns what you see right side up again.

Since their invention, all three types of telescopes have been altered and improved in order to enable the user to adjust the focus. In the newer models there are two tubes instead of one, a wider tube containing the objective lens, and a narrower tube, which can be slid in or out, containing the eyepiece. In the terrestrial telescope, the magnifying power can be adjusted too - the farther apart the two lenses of the eyepiece are, the greater the magnifying power. With the astronomical type, you have to change the eyepiece in order to change the power, but astronomers are prepared to do that rather than have an extra lens, which absorbs a bit of the precious light they need for their observations.

Telescopes that use only lenses are called refracting telescopes, as lenses refract light (more on that in later years). However, refracting telescopes of any design have a problem: the objects seen at the edge of the field of view appear to have colour fringes because of the way light bends differently along the edges of the glass. Modern refracting telescopes use several lenses in the eyepiece to solve that problem, but in 1688, Isaac Newton solved it by using mirrors instead of lenses &ndash he invented the reflecting telescope, so called because mirrors reflect light &ndash so telescopes that use his design are called Newtonian telescopes. Many improvements have since been made on Newton&rsquos design, and these days professional astronomers use reflecting telescopes almost exclusively.

The amount by which a telescope magnifies distant objects is called the telescope&rsquos power. Basically, the weaker the objective lens or mirror is and the stronger the eyepiece is, the more powerful the telescope will be. Aside from magnifying things, astronomers want to see things that are too dim to be seen with the naked eye, and the bigger the objective lens or mirror is, the more light it will gather. Suppose you double the diameter (the width) of the objective lens or mirror. Will it gather twice as much light? Nope! The amount of light it gathers depends on its area , not its diameter. You&rsquore making the lens twice as wide and twice as long, so you make the area two times two (four) times as big, so it will gather four times as much light. If you triple the diameter, you make the area, and therefore its light gathering power, three times three (nine) times as big. How much more light will it gather if you make the diameter four times as big?

At this point you&rsquoll have to indulge me for introducing a bit of mathematics, which will be needed in later lessons even in Year One. If you take any number and multiply it by itself, you get the square of that number. The square of 1 is 1, the square of 2 is 4, the square of 3 is 9, and so on. The square of a number is represented by a superscript 2. For example, 2 2 = 4.

Another advantage of making the objective lens or mirror bigger is that it improves the resolution of the telescope &ndash that is, how close together two points of light can appear to be and still be seen as two distinct points instead of one. The reason for this will be discussed in Year Six. Of course, by close together I don&rsquot mean the distance between them in miles or kilometers. If one of the two points of light is between you and the other one, they can be trillions of miles apart and still appear to be close together, whereas if you are between them, they could be close to you and still appear far apart. The observed closeness of two points of light is measured as an angle, not a straight-line distance.

The ancient Greeks divided the circle into 360 degrees. If one star is on the eastern horizon and another one is on the western horizon, they are half a circle &ndash 180 degrees &ndash apart. You would have to turn your head halfway around to look from one to the other. If they are 1/180 th of that distance apart, then they are one degree apart, and you would only have to move your eyes a little bit to move from the first to the second. Now, someone with average vision can, at best, distinguish two points of light about 1/20th of a degree apart with the naked eye. However, astronomers have a need to see objects that appear much closer together than that. Rather than writing many tiny fractions of a degree to describe the observed closeness between two stars, they use even smaller units known as arcminutes and arcseconds. A degree is divided into 60 arcminutes and an arcminute is divided into 60 arcseconds.

If you double the diameter of the objective lens or mirror, you double the resolution &ndash that is, you can resolve two stars that appear twice as close together. If the diameter of a lens or a mirror is about 12 centimeters, the resolution is about one arcsecond. Telescopes are getting bigger and bigger the biggest one so far is the Keck telescope, 10 meters in diameter. Can it resolve two stars that are 0.012 arcseconds apart? Not without a very expensive trick. The problem is that movement of the air makes the stars appear to move around (and twinkle too), making it hard to achieve a resolution much better than one arcsecond no matter how big the telescope is. Large modern telescopes solve this problem by using what is called adaptive optics, in which the mirror deforms hundreds of times per second to compensate for the apparent movement of the stars. But there is another solution to this problem: putting your telescope above the atmosphere by launching it into orbit around the Earth, which brings us to our next tool used by Muggle astronomers.

Satellites

A satellite of a planet is an object that is in orbit around the planet. Moons are natural satellites, whereas an artificial satellite is a man-made object launched into orbit by means of a rocket. Artificial satellites have many purposes. Muggles have what is called a GPS (Global Positioning System) that uses satellites to locate the position of a receiver, like the ones in Muggles&rsquo cars. Satellites are also used for communication, like telephone, television, and internet transmission, to look at and photograph the Earth, to examine clouds, temperature, and rainfall to make more accurate weather forecasts, and, of course, to put telescopes above the atmosphere, which is one contribution that they make to astronomy. The Hubble telescope, named after Edwin Hubble, is one such telescope orbiting Earth. It is about 2.5 meters wide, so it should be able to resolve two stars that are 0.05 arcseconds apart. But when it was launched in 1990, its resolution was more than one arcsecond! A flaw in the primary mirror was found to be responsible for the blurred images. A team of astronauts was sent up in 1993 to correct the problem, after which the resolution improved to the expected 0.05 arcseconds. Since then it has sent sharp and beautiful pictures back to Earth and made many important discoveries, including finding distant galaxies and black holes, improving the accuracy of the rate at which the universe is expanding, showing that the rate of expansion is accelerating, and estimating more precisely the age of the universe. If you would like to see some of these pictures and learn more about what astronomers have learned from the Hubble telescope, there is further reading here , which in turn provides further sources for more in-depth reading.

Satellites have other uses besides carrying telescopes: they house other tools like cameras, radars, and remote sensors, tools to collect and analyze space particles, and more that give us other important information. Some of them also carry people, which serves to arouse public interest in space travel and increase the prestige of the country that launches them. The space race between the United States and the Soviet Union during the Cold War between those two nations is a prime example.

Sputnik.
Source: here

The first satellite, called Sputnik - a Russian word meaning &ldquofellow traveler&rdquo - was launched in 1957 by the Soviet Union. By the time the United States had successfully launched its first satellite four months later &ndash Explorer 1 &ndash after some embarrassing failures, the Soviet Union had already launched their second satellite, which carried a dog named Laika. Shortly thereafter, they launched their third satellite, which carried the first man into outer space &ndash Yuri Gagarin, grandfather of Professor Gagarina, a former professor of this course. This was a wake up call for the United States, because satellites can also be used to spy. The Americans responded in 1958 by creating the National Aeronautics and Space Administration (NASA) to catch up with the Soviet Union in the space race, and they also greatly increased funding for universities to create a pool of future rocket scientists. If you would like to learn more about NASA, there is further reading here . The United States finally won the space race in 1969 when they landed two men, Neil Armstrong and Buzz Aldrin, on the Moon and brought them safely back to Earth. Further information can be found here . While they were on the Moon, the command module, piloted by Michael Collins, orbited the Moon, so it too was an artificial satellite. After six more voyages to the Moon, one of which failed to land there (Apollo 13), the country lost interest, and since then astronauts and cosmonauts (Russian astronauts) have only been sent into low Earth orbit.

But the Soviet Union was still ahead in one area &ndash launching a woman into space. In 1963 Valentina Tereshkova, a textile worker who later became an engineer, spent almost three days in space. Several female American pilots, believed to be better trained than Tereshkova, were not sent into space because of prejudice in the United States where it was thought that women were unfit for space travel. Twenty years were to pass before the Americans first launched a woman into space &ndash Sally Ride. Since then, NASA no longer takes gender into consideration in evaluating candidates for space travel.


Valentina Tereshkova.
Source: here

Spacecraft have orbited other celestial bodies besides Earth and our moon in fact they have orbited all the planets, some of their moons (like Saturn&rsquos biggest moon Titan), and some asteroids and comets, and have given astronomers much information about them.

Space Agencies in Other Countries

The United States and Russia are not the only countries that have space programs. Several European countries contribute to the European Space Agency, and there are space agencies in numerous other countries including Canada, India, Japan, and China. Sometimes they go it alone - for example, the China National Space Administration first landed a rocket on the far side of the Moon on January 3, 2019 - and sometimes they cooperate with each other in their space programs. For example, the Americans, Russians, Europeans, Canadians, and Japanese cooperated to build the International Space Station, which is also a satellite, and which often houses people from more than one country at the same time. Some wizards have actually worked under cover with those other space agencies, but not in NASA, because in 1790 MACUSA, the American equivalent of the British Ministry of Magic, passed Rappaport&rsquos Law, an edict enforcing total segregation between magical people and No-Majs (the American name for Muggles). As a Canadian, I can&rsquot resist mentioning that Canada invented the Canadarm, a robot that is attached to an artificial satellite and used to deploy, maneuver, and capture payloads. Of course, people and supplies have to be transported to and from the International Space Station, which brings us to our next tool used by Muggle astronomers.

Space Shuttles

In the early 1980s, NASA began a program called the Space Transportation System, using artificial satellites, called space shuttles , that are partially or totally reusable. They were used to launch numerous other satellites, interplanetary probes, and the Hubble Space Telescope to conduct science experiments in orbit and to participate in the construction and servicing of the International Space Station. There were two accidents on space shuttles, which killed a total of 14 astronauts. The program was terminated in 2011, and since then the United States has been relying on the Russian spacecraft Soyuz to transport astronauts and supplies to and from the International Space Station. The United States is working on a couple of new programs, which are on schedule for first flights in 2019 and 2020. Update: The first unmanned flight was docked with the International Space Station on March 3, 2019 and brought supplies to the three astronauts on board. Further information about space shuttles can be found here .

Radar

Long-range radar antenna , used to track space objects and ballistic missiles.
Source: here

Many of you who grew up in Muggle households probably think of radar as a device used by the military to detect enemy planes and missiles. Well, that was the purpose for which it was invented, but it has many other uses as well. Radar is a detection system that uses radio waves or microwaves to determine the range, angle, or velocity of objects. You can imagine it like throwing many small bouncy balls against a wall to see where they bounce back to. A radar bounces waves off an object and studies those that are reflected by the object. It has many uses besides military: air and ground traffic control, locating landmarks and ships at sea, ocean surveillance, monitoring the weather, geological observations, and (our subject of interest) radar astronomy. Many astronomical objects have been studied by radar: the Moon, Venus, Mars, Mercury, the four biggest moons of Jupiter, Saturn&rsquos rings and its largest moon, Titan, and a few nearby asteroids and comets. With radar, astronomers get information about the surface of these objects, which we wizards then find useful in our study of how they affect our magic (Lessons Four, Five, and Six will discuss this matter further). Further information about radar and radar astronomy can be found here and here , respectively.

Rovers

A rover is a vehicle designed to move across the surface of a planet or a moon. Some have been designed to transport people, whereas others are robots that are either driven from the Earth or are self-driving. Rovers are used to study the planet or moon they land on by taking pictures, readings of the atmosphere, or samples of dust and rock. So far, rovers have only been landed on the Moon and Mars, and all of them but one - Yutu, a Chinese lunar rover - were launched either by the United States or Russia. One of those rovers, called Curiosity, launched by the United States, is currently searching for evidence of past or present life on Mars and generally trying to determine whether the planet could ever have supported life. Further information about rovers can be found here .

Side-by-side images depict NASA's Curiosity rover (illustration at left) and a moon buggy driven during the Apollo 16 mission.
Source: here

If a rover can be driven from the Earth, the driver can decide at any moment what is the most interesting place for it to visit. But to do so, he has to see quickly how the rover is responding to his commands. A signal does not arrive at its destination the instant it is sent it travels at the speed of light, which is very fast, but if the distance between the source and the destination is too great, the delay makes driving a rover from the Earth impractical. A rover on the Moon can be driven from the Earth because it takes only one and a quarter seconds for a signal to travel from the Earth to the Moon or from the Moon to the Earth. But a rover on Mars has to be self-driving because it takes at least four minutes, and sometimes as long as 24 minutes, for a signal to travel between the Earth and Mars.

And that brings us to the end of our study of some of the important astronomical tools that have been invented by Muggles. In our next lesson we will study some of the magical astronomical tools utilized by wizarding astronomers. Meanwhile, you will have two assignments to do, both retakeable. In the quiz, you will be required to do some research to answer one of the questions. The essay, which is not mandatory, will require you to summarize some information from an outside source that will be provided.

I see that some of you are already looking at the time. Well, now that you&rsquore finally free to go &hellip hey, easy now! You can&rsquot all fit through the door at the same time.

NOTE - All the new Year One lessons have been published. All my assignments are open book: you can consult the lessons while doing them, but for some questions the lessons don't contain the answers, only the information that will enable you to deduce the answers, which will require logical thinking. If you have completed the current Year One course, you are not required to do the new one, but it would be advisable to do so, because the material in it will be tested on your O.W.L. exam. If you haven't completed the current course, it's your choice whether or not to do so before the new material is posted.

Ever wonder what is beyond this Earth? Yes, the night sky may be beautiful, but knowledge of the heavens will also help you become a better witch or wizard. In Year One, you will observe the skies with a magical telescope, learn about our solar system neighbors, and discover how magic reflected off astronomical objects can affect us all on Earth. Come join us in Astronomy 101 - it’s an out of this world adventure! Enroll


Watch the video: Η Ζωή μας ένας καθρέφτης πώς να καθρεφτίσεις αυτό που θέλεις- ΓΩΝΗ ΜΟΥΚΑ (May 2022).