Astronomy

Milky Way position on the sky

Milky Way position on the sky


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I'm looking for some sort of boundary data to be able to render the milky way on a star map, as visible from Earth. Something that looks like this:

For that, I need something like a collection of RA hours and DEC degrees of the "boundary points" of what's visible from Earth (technically the Galactic Center), possibly with proper motion too. I'm not looking for precise luminosity data or anything like that, just the points of the blob on the sky that most resembles the Milky Way's shape and position from the Earth. It's important that I want to render the sky map for any given surface point on Earth, for any given time (within the last 100 years at least).

Do you know of a database like that? I've been looking on VizieR but I couldn't find what I was looking for.


There is a very nice project called d3-celestial by Olaf Frohn on github. In contains a data file describing the Milky Way as polygons, see here. A demo showing this Milky Way can be found here. And even better, the source for this data is cited, pointing to the Milky Way Outline Catalog by Jose R. Vieira.

Depending on your project, the json format from d3-celestial might be easier to read than the one from Jose R. Vieira. Note that you don't have to worry about these "contours" moving on a time scale of hundred years, but this is another question.


From memory (I don't have a copy here right now) the HNSky package used to have a hand-drawn "supplement" file for the milky way. It contained a lot of data points arranged as RA & Dec points and was extracted from photographs, with a bit of correction and scaling.

I suggest you load and install one of the older versions still on HN Sky's page, such as 3.0.0, and look for the supplement file. (The newer version 3.2.3 does not seem to include this file.)

This is only position data - no proper motion, etc. as the question mentioned. So only a partial answer.

(Note: You might need to ask the authors of that file for permission if you're going to release software based on this. No harm in looking at it for purely personal interest of course.)


The planetarium software, Guide, to be found at ProjectPluto.com, has a map of the Milky Way. This is how the dataset is described

"The Nebula Databank was compiled by Eric-Sven Vesting to evade the problems that came with earlier bright nebula databases. For example, previous versions of Guide gathered nebula data from five separate catalogs. There were few cross-indexes from one catalog to another, and no way to indicate that one designation applied to a part of larger area with a different designation. Also, brightness levels were applied in an inconsistent manner at best. The Nebula Databank contains explicit links between the various nebula catalogs, enabling Guide to show all designations for a given object and to avoid drawing some objects twice (if they appeared in separate catalogs under different names). Also, Eric-Sven Vesting created the nebula isophotes used by Guide to indicate the shapes of most prominent nebulae. Better positional data was generated, usually by comparing catalog positions to actual RealSky images."

(I hope I have not violated any copyright on this).

It's not clear where that database is, but perhaps you could contact either ProjectPluto or Eric-Sven Vesting directly.

I have no affiliation or connection, financial or otherwise, with this software.


Where is the Milky Way on May evenings?

In the month of May, if you’re in a dark location at northern temperate latitudes, you might be searching for one of the sky’s most spectacular sights, the starlit band of the Milky Way. You won’t find it in the early part of the night. That luminous band of stars arcing across the dome of sky is nowhere to be seen as evening falls in May. Where is the the Milky Way at nightfall this month?

For starters, remember that the disk of our Milky Way galaxy is flat, like a pancake. At northern temperate latitudes, as evening falls in the month of May, the plane of the pancake-shaped galactic disk pretty much coincides with the plane of your horizon.

Because the Milky Way rims the horizon in every direction at nightfall and early evening, we can’t see this roadway of stars until later at night. Then … whoa! Beautiful.

Starlit band of the Milky Way. Photo by Larry Landolfi via NASA

The galactic disk rims the horizon at about 30 degrees North latitude – the latitude of St. Augustine, Florida. Appreciably north of this latitude, the galactic disk tilts a bit upward of the northern horizon. Appreciably south of 30 degrees north latitude, the galactic disk tilts a bit above the southern horizon.

Even so, the Milky Way is pretty much out of sight in our Northern Hemisphere sky during the evening hours in May.

Like the sun, the stars rise in the east and set in the west. If you stay up until late night – near midnight in early May, a couple of hours earlier by June – you’ll begin to see the the stars of the Summer Triangle – Deneb, Vega, and Altair – rising above your eastern horizon.

In a dark country sky, the Milky Way’s band of stars becomes visible as well, for the Milky Way passes right through the Summer Triangle. Watch for it, if you’re up late this month.

An all-sky plot of the 25,000 brightest, whitest stars shows how these stars are concentrated along the Milky Way. This map shows our limited, inside view of the Milky Way galaxy. The large, dark patch near the middle of the picture is due to nearby dark nebulae, or clouds of gas and dust, which obscure the stars. Via altasoftheuniverse.com.

Bottom line: The Milky Way’s softly-glowing band of luminescence hides behind the horizon at nightfall and early evening in the month of May. But if you stay up until around midnight, you’ll begin to see the starlit band of the Milky Way rising in the eastern sky.


Astronomers release new all-sky map of the Milky Way’s outer reaches

Astronomers using data from NASA and ESA (European Space Agency) telescopes have released a new all-sky map of the outermost region of our galaxy. [Editor’s note: See Related Multimedia link below.] Known as the galactic halo, this area lies outside the swirling spiral arms that form the Milky Way’s recognizable central disk and is sparsely populated with stars. Though the halo may appear mostly empty, it is also predicted to contain a massive reservoir of dark matter, a mysterious and invisible substance thought to make up the bulk of all the mass in the universe.

The data for the new map comes from ESA’s Gaia mission and NASA’s Near Earth Object Wide Field Infrared Survey Explorer, or NEOWISE, which operated from 2009 to 2013 under the moniker WISE. The study makes use of data collected by the spacecraft between 2009 and 2018.

The new map reveals how a small galaxy called the Large Magellanic Cloud (LMC) — so named because it is the larger of two dwarf galaxies orbiting the Milky Way — has sailed through the Milky Way’s galactic halo like a ship through water, its gravity creating a wake in the stars behind it. The LMC is located about 160,000 light-years from Earth and is less than one-quarter the mass of the Milky Way.

Though the inner portions of the halo have been mapped with a high level of accuracy, this is the first map to provide a similar picture of the halo’s outer regions, where the wake is found — about 200,000 light-years to 325,000 light-years from the galactic center. Previous studies have hinted at the wake’s existence, but the all-sky map confirms its presence and offers a detailed view of its shape, size, and location.

This disturbance in the halo also provides astronomers with an opportunity to study something they can’t observe directly: dark matter. While it doesn’t emit, reflect, or absorb light, the gravitational influence of dark matter has been observed across the universe. It is thought to create a scaffolding on which galaxies are built, such that without it, galaxies would fly apart as they spin. Dark matter is estimated to be five times more common in the universe than all the matter that emits and/or interacts with light, from stars to planets to gas clouds.

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Although there are multiple theories about the nature of dark matter, all of them indicate that it should be present in the Milky Way’s halo. If that’s the case, then as the LMC sails through this region, it should leave a wake in the dark matter as well. The wake observed in the new star map is thought to be the outline of this dark matter wake the stars are like leaves on the surface of this invisible ocean, their position shifting with the dark matter.

The interaction between the dark matter and the Large Magellanic Cloud has big implications for our galaxy. As the LMC orbits the Milky Way, the dark matter’s gravity drags on the LMC and slows it down. This will cause the dwarf galaxy’s orbit to get smaller and smaller, until the galaxy finally collides with the Milky Way in about 2 billion years. These types of mergers might be a key driver in the growth of massive galaxies across the universe. In fact, astronomers think the Milky Way merged with another small galaxy about 10 billion years ago.

“This robbing of a smaller galaxy’s energy is not only why the LMC is merging with the Milky Way, but also why all galaxy mergers happen,” said Rohan Naidu, a doctoral student in astronomy at Harvard University and a co-author of the new paper. “The wake in our map is a really neat confirmation that our basic picture for how galaxies merge is on point!”

A Rare Opportunity

The authors of the paper also think the new map — along with additional data and theoretical analyses — may provide a test for different theories about the nature of dark matter, such as whether it consists of particles, like regular matter, and what the properties of those particles are.

“You can imagine that the wake behind a boat will be different if the boat is sailing through water or through honey,” said Charlie Conroy, a professor at Harvard University and an astronomer at the Center for Astrophysics | Harvard & Smithsonian, who coauthored the study. “In this case, the properties of the wake are determined by which dark matter theory we apply.”

Conroy led the team that mapped the positions of over 1,300 stars in the halo. The challenge arose in trying to measure the exact distance from Earth to a large portion of those stars: It’s often impossible to figure out whether a star is faint and close by or bright and far away. The team used data from ESA’s Gaia mission, which provides the location of many stars in the sky but cannot measure distances to the stars in the Milky Way’s outer regions.

After identifying stars most likely located in the halo (because they were not obviously inside our galaxy or the LMC), the team looked for stars belonging to a class of giant stars with a specific light “signature” detectable by NEOWISE. Knowing the basic properties of the selected stars enabled the team to figure out their distance from Earth and create the new map. It charts a region starting about 200,000 light-years from the Milky Way’s center, or about where the LMC’s wake was predicted to begin, and extends about 125,000 light-years beyond that.

Conroy and his colleagues were inspired to hunt for LMC’s wake after learning about a team of astrophysicists at the University of Arizona in Tucson that makes computer models predicting what dark matter in the galactic halo should look like. The two groups worked together on the new study.

One model by the Arizona team, included in the new study, predicted the general structure and specific location of the star wake revealed in the new map. Once the data had confirmed that the model was correct, the team could confirm what other investigations have also hinted at: that the LMC is likely on its first orbit around the Milky Way. If the smaller galaxy had already made multiple orbits, the shape and location of the wake would be significantly different from what has been observed. Astronomers think the LMC formed in the same environment as the Milky Way and another nearby galaxy, M31, and that it is close to completing a long first orbit around our galaxy (about 13 billion years). Its next orbit will be much shorter due to its interaction with the Milky Way.

“Confirming our theoretical prediction with observational data tells us that our understanding of the interaction between these two galaxies, including the dark matter, is on the right track,” said University of Arizona doctoral student in astronomy Nicolás Garavito-Camargo, who led work on the model used in the paper.

The new map also provides astronomers with a rare opportunity to test the properties of the dark matter (the notional water or honey) in our own galaxy. In the new study, Garavito-Camargo and colleagues used a popular dark matter theory called cold dark matter that fits the observed star map relatively well. Now the University of Arizona team is running simulations that use different dark matter theories to see which one best matches the wake observed in the stars.

“It’s a really special set of circumstances that came together to create this scenario that lets us test our dark matter theories,” said Gurtina Besla, a co-author of the study and an associate professor at the University of Arizona. “But we can only realize that test with the combination of this new map and the dark matter simulations that we built.”

Launched in 2009, the WISE spacecraft was placed into hibernation in 2011 after completing its primary mission. In September 2013, NASA reactivated the spacecraft with the primary goal of scanning for near-Earth objects, or NEOs, and the mission and spacecraft were renamed NEOWISE. NASA’s Jet Propulsion Laboratory in Southern California managed and operated WISE for NASA’s Science Mission Directorate. The mission was selected competitively under NASA’s Explorers Program managed by the agency’s Goddard Space Flight Center in Greenbelt, Maryland. NEOWISE is a project of JPL, a division of Caltech, and the University of Arizona, supported by NASA’s Planetary Defense Coordination Office.

Provided by: Harvard-Smithsonian Center for Astrophysics


How To Know Where & When The Milky Way Will Appear

I get asked fairly often how I'm able to anticipate or predict when the Milky Way and other celestial objects will be in position in the skies above for my photography. In that direction, I wanted to share that I use a combination of knowledge and software tools to help boost that knowledge and understanding.

In looking back in history, it wasn't that long ago that I asked myself the same questions. I was following some other excellent night photographers where it suddenly hit me that these guys were definitely not guessing - they knew what to expect before heading out in the darkness. So I started doing some research to see what pc-based tools I could find - mostly from the astronomy side of photography.

Option #1 - Stellarium
Shortly after starting the hunt, I found a free software application called Stellarium (from http://www.stellarium.org/) which helped to wet my appetite. Considering the price (did I say it was free?), it's hard not to recommend that people at least take a look at this option.

Option #2 - SkyGazer
In search of more, I ended up purchasing another program called SkyGazer 4.5 (from http://www.carinasoft.com/skygazer.html) and used it for several years with good success. At just $29 for an online download, I have to recommend this option as having very good overall value.

Option #3 - Starry Night
More recently, I took a look at another software application and was impressed with its combination of functionality and realism - called Starry Night. I decided to buy the more advanced pro edition from http://astronomy.starrynight.com/ as it includes data for comets - something I felt was worth the extra expense. My testing shows it as the clear winner - with improved realism and features. In-fact, I've been so impressed with Starry Night, that I've dedicated myself to learning how to make the most of it. And while the Pro Edition cost $149, an online download of the regular edition is available for just $49.95. I found this to have the best overall value and is therefore my best recommendation from the bunch.

Understanding Milky Way Patterns
Along the way, I learned that the Milky Way follows some patterns that are very helpful to understand. In general, it appears at certain times of the night as a faint, wide, cloudy line of stars that runs from North to South. And while it is visible at any time of the year, those in North America will get their best view of the Milky Way in the summer months from May through September. This is when the brightest, most visible portion of the Milky Way near the center of the galaxy is high enough in the sky to be seen when looking toward the south. In spring, the Milky Way appears for a few morning hours before twilight, in the summer for much of the night, and in the fall for a few evening hours after twilight.

Summary - Favorite Astronomy Software Applications
At their minimum, all three of these software applications do a good job of helping to become more aware of the timing of celestial objects in the skies overhead. And while I may have my favorites, they all do a good job of helping you to predict and anticipate where the Milky Way and other objects will appear.

  • Stellarium
    1. Cost: free
    2. Rating: Initially helpful, but lacks some advanced features
    3. Available from: http://www.stellarium.org/
  • Sky Gazer
    1. Cost: $29 for an online download
    2. Rating: Very Good Overall Value
    3. Available from: http://www.carinasoft.com/skygazer.html
  • Starry Night
    1. Cost: $49.95 for an online download (with more advanced options available)
    2. Rating: Best Of The Bunch
    3. Available from: http://astronomy.starrynight.com/

I hope these tools help in your knowledge and understanding of what goes on in the skies above. Let me know if you run into any questions.


The distribution of deep sky objects

Because we lie within the disk of the galaxy, it appears as a band of light which encircles the entire sky.

The chart below shows the distribution of various kinds of deep sky object across the night sky. The blue dots represent open star clusters, which are heavily concentrated in the plane of the galaxy. The green dots represent globular star clusters, which are seen all around the sky, but concentrate particularly around the constellation Sagittarius, at a right ascension of around 18 hours. This is the direction in which the center of the galaxy lies.

The red dots show external galaxies, which are more distant. They tend to be seen predominantly away from the plane of the Milky Way. This has nothing to do with their physical distribution in space, but is merely because it is harder to see galaxies which lie behind the plane of the Milky Way, as there is too much material in the way.


Source: NGC2000.0.


Viewing our galaxy

The Our Galaxy app can be operated in two modes that are enabled by tapping Galaxy or Sky on the app's toolbar. The toolbar also features icons to open the search menu and Views library, read a page of information about the selected object, toggle red-light night mode, open the app's settings menu and help. Two whimsical spaceship-shaped icons in the toolbar serve as zoom controls &mdash one flies you closer, the other flies you out.

Galaxy View presents a 3-dimensional model of our Milky Way's barred spiral form that you can tilt and rotate, and zoom in and out of. A single tap in the Settings Orientation menu lets you select preset orientations, such as an edge-on view and a face-on view. In the Center menu, you can choose to keep our sun in the center, or rotate around the galactic core or around a selected star or deep-sky object. Across the top of the screen are shown your distance from the selected object, and the field of view (FOV) being displayed in light-years.

Sky View draws a rectangular (orthographic) map of the entire sky as viewed from Earth. Sky coordinates in degrees are labelled around the perimeter of the map. The major stars and lines that form the constellations are plotted in white on a black background. The deep-sky objects are overlain using colored symbols. The map can be enlarged and panned around. Tapping a symbol shows its object's name. Plotting one or more categories of deep-sky objects on the map view illustrate how they can be used to define our galaxy's structure, or be completely independent of it &mdash all useful information for understanding how galaxies like ours are structured. A single tap switches between sky and galaxy view.

The app is highly configurable. You can decide whether to display labelled names next to the symbols, identify the various spiral arms of the galaxy, and show the Constellation Sectors &mdash the portions of the Milky Way that lie in the direction of certain constellations, such as Orion, Gemini or Cygnus.

To clean up the view, simply enter the settings menu and tap the remove options.

The app contains an extensive library of stars and objects. An object can be selected by typing its name or its designation into the search menu &mdash or by tapping its symbol on the screen. Multiple deep-sky objects can be displayed at the same time, as I describe below.

The app's powerful search menu allows you to type all or a portion of an object's name or designation, include or exclude object types, and limit the search to specific ranges of magnitude (brightness), distance, age, size and more. You can even search all constellations, or select a single constellation.

The list of results can then be displayed on the map or 3D model. It's especially interesting to see how the stars and deep-sky objects of a single constellation fall at vastly different distances from our sun.

The more you work with the app, the more you will learn about astronomy, astrophysics, and cosmology &mdash all presented using clear, understandable text and graphics.

The Views library is especially educational for understanding how various classes of objects populate the galaxy. Nine categories are offered: individual stars and OB Associations (hot, bright stars), open and globular clusters, various types of nebulas, galaxies, and our galaxy's structural components. There is also an entry for the list of well-known Messier objects. Each entry has an information icon to summon a description of that object class.

Tapping any category opens a sublist that allows you to select all members of the class, or sub-groups. For example, in the Diffuse Nebulae view, you can treat emission and reflection nebulas as separate groups, or combined, each type color-coded appropriately (with red for light emitted from hydrogen, blue for starlight scattered off dust, and green for both phenomena).

The Visibility menu contains sliders to plot galactic axes and to add wire mesh representations of the galaxy's central bulge, dark matter halo sphere, and more.

For cosmology buffs, the app contains 3D locations for hundreds of galaxies. Selecting the galaxy category and using "Galaxy view" puts you 92 billion light-years away from home. Manipulating the model shows how some galaxies concentrate in groups while others leave empty voids in the visible universe.

The Our Galaxy app will give you a true perspective on our place in space. Bill Tschumy has posted a YouTube video demonstration of the app here. Enjoy exploring the galaxy and, as always, keep looking up!

Chris Vaughan is an astronomy public outreach and education specialist at AstroGeo, a member of the Royal Astronomical Society of Canada, and an operator of the historic 74-inch (1.88-meter) David Dunlap Observatory telescope. You can reach him via email, and follow him on Twitter @astrogeoguy, as well as on Facebook and Tumblr. Follow SkySafari on Twitter @SkySafariAstro. Follow us on Twitter @Spacedotcom and on Facebook.


Breathtaking Milky Way timelapse shows how the night sky will change in 400,000 years

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Milky Way: 1.6 million year time-lapse revealed

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The Milky Way has been around for more than 13 billion years and in that time it has changed a lot. Galactic impacts and mergers with our nearest cosmic neighbours mean the galaxy's landscape is always on the move. And down on the Earth, factors such as the planet's movement and precession mean our ancestors 40,000 years ago looked upon a very different night sky.

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The same is true for the future, according to a breathtaking new timelapse published by the European Space Agency (ESA).

The timelapse shows just how different the night sky will look 400,000 years from now.

Astronomers have simulated a timelapse of how the 40,000 stars nearest to our solar system will move about in the coming millennia.

The stars are all within 325 light-years of the Sun and were mapped out by ESA's Gaia space observatory.

You can watch Milky Way the timelapse in the embedded video above.

Milky Way timelapse: The simulated movement of 40,000 stars in the agalxy (Image: ESA/Gaia/DPAC, CC BY-SA 3.0 IGO)

Milky Way timelapse: The night skies will look very different thousands of years from now (Image: ESA/Gaia/DPAC, CC BY-SA 3.0 IGO)

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Each streak of light represents a real celestial body moving across the Milky Way in increments of 80,000 years.

The trails also indicate how bright the stars appear today.

Because stars all move in their orbits of the galactic centre, their apparent position in the sky relative to other stars changes.

Astronomers refer to this movement as proper motion and it is more or less dramatic for different stars.

In the ESA timelapse, some of the stars produce shorter streaks which indicate stars moving at a sluggish pace, while faster stars leave behind longer tails.

Dinosaurs roamed Earth on other side of Milky Way says scientist

ESA said: "The displacement on the sky is dictated by the distance of the star and the speed at which it moves.

"Stars that are nearby and moving at high speeds will change position across the sky quickly, while stars that move at intrinsically lower speeds or are far away will change position slowly."

You will also notice the stars appear to concentrate on the right side of the timelapse as if attracted by some unseen force.

But this is the result of the motion of our Sun in respect to the other stars.

Like all bodies in the Milky Way, the Sun is on the move and that causes the apparent shift of other stars in the opposite direction.

Stargazing tips: Quick guide for amateur astronomy enthusiasts (Image: EXPRESS)

Milky Way timelapse: The Gaia spacecraft has charted some 1.8 billion objects (Image: ESA)

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ESA said: "If you imagine yourself moving through a crowd of people (who are standing still), then in front of you the people will appear to move apart as you approach them, while behind you the people will appear to stand ever closer together as you move away from them.

"This effect also happens due to the motion of the Sun with respect to the stars.

"Hence the Sun is moving toward a point on the sky in the upper left quadrant of the video, while it moves away from the lower right quadrant."

From start to end, the simulation spans an incredible 1.6 million years of simulated history.

But the very last frame of the video focuses on the night sky just 400,000 years from now.

Related articles

ESA said the decision was made to avoid too much crowding from the white star trails.

Gaia's latest trove of data was published on December 3 this year.

The data charts the position of some 1.8 billion objects, including 330,000 stars

Astronomers believe the collected information has created the most detailed map of the Milky Way yet, which will go a long way towards understanding our place in the Universe.


Milky Way position on the sky - Astronomy

All of us love and chase the Milky Way looking for new compositions that transmit our thoughts to the world. Some of you sure need to predict it to prepare workshops and photography trips. At the end of the day, every landscape photographer needs a way to better understand and predict the Milky Way and, in particular, the Galactic Center .

In the article “How To Shoot Truly Contagious Milky Way Pictures”, we explain everything you need to turn your Milky Way ideas into real images, step by step from inspiring sources and equipment to camera settings. In this article, you'll learn the planning part in detail.

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Milky Way: The Definitive Photography Guide

Also, as we learnt in another How-To article, PhotoPills’ Night Augmented Reality tool comes in handy when planning our Milky Way shots but, with the arrival of the 2D Map-Centric Milky Way Planner, we go a few steps further making the planning even easier.

Interested in mastering Milky Way planning with both the Night Augmented Reality view and the 2D Map-Centric Planner? Then, watch the following video. You'll love it!

If you want to shoot the Galactic Center aligned with a special subject you know (rock formation, lighthouse, tree, etc) or wish to capture the whole Milky Way arch above an ancient stone construction, the 2D Milky Way Planner is for you.

No matter the location on Earth you are or plan to go, this tutorial will help you learn the hidden secrets within this new photographic Pill allowing you to quickly plan any Milky Way photo you imagine.

But… first things first! The 2D Milky Way Planner includes a few things that need to be explained in detail before you start planning like crazy. Be patient, don’t hurry up, keep in mind Molière’s wise words:

"Trees that are slow to grow bear the best fruit."

Let’s start with the basics!

Content

1 How Can I Activate The 2D Map-Centric Milky Way Planner?

The first thing you need to learn is where to find the button that activates the 2D Miky Way Planner.

On the Planner, place the Observer's pin near a subject that interests you. In this example, I've placed it near the Naveta d’Es Tudons, the most remarkable megalithic chamber tomb in Europe.

Above the map (first screenshot), you see the sun/moon rise/set information panel. Drag the top panels to the left until you get to the Galactic Center visibility information panel. It’s the one following the Magic Hours’.

This panel is telling you that the Galactic Center is always invisible during the night between December 21 st and 22 nd 2014. As I explained in the article How to Plan the Milky Way Using The Augmented Reality, the Galactic Center will not be properly visible until March 2015 (Northern Hemisphere).

Notice that, on the left-hand side of the panel, there is a button with a kind of Milky Way icon on it. This is a three state button which allows you to control what is displayed on the map: (i) only sun and moon, (ii) sun, moon and Milky Way altogether or (iii) only Milky Way.

Tap on this button to activate the 2D Milky Way map representation. The icon of the button is telling you that sun, moon and Milky Way information is displayed on the map. If you wish to work with the Milky Way only, just tap on it again. Now, the sun and moon azimuth lines have disappeared and the icon of the button is only showing you the Milky Way.


Sun, moon and Milky Way map representation activated.
  • At the moment, the Milky Way arch is not displayed on the map. This is because the time is set at 12:49pm (daytime) and PhotoPills will only show you the Milky Way arch during nighttime.

If you dare to include the moon and the Milky Way in the same image, tap again on the button until you see the sun, moon and Milky Way information displayed on the map. Then, got to the sun/moon position information panel and tap on the sun/moon button to switch off the sun azimuth lines. Go back to the Galactic Center Visibility panel. Notice that the icon of the Milky Way button adjusts too.


Tap on the sun/moon button from the sun/moon position information panel to switch off the sun azimuth lines.
Now you can go back to the Galactic Center visibility panel and work with the Milky Way and the moon only.

2 How Is the Milky Way Arch Displayed On The Map?

The concentric thin gray circumferences you see around the Observer’s pin (red pin) will help us assess the elevation of the Milky Way arch and its position in the sky: near the horizon, above it or just above our heads.

The elevation between two consecutive circles is 10⁰. The outer circumference represents an elevation of 0⁰, when the arch is low in the sky, at the horizon level. The following one represents 10⁰ and so on (20⁰, 30⁰,etc) until 90⁰, when the arch is just above the observer’s pin. Summing up, these circumferences help us visualize whether the Milky Way arch is low in the sky, near the horizon, or above our heads.

As I said before, PhotoPills considers that the Milky Way will become visible only when it's completely dark. Thus, the Milky Way is only displayed on the map during nighttime, which is the period of time between the end of the evening astronomical twilight and the beginning of the morning astronomical twilight, when the sun is below -18⁰.

To see the Milky Way displayed on the map, move time forward to the end of the evening astronomical twilight (7:00pm). It's the white dotted arch you see in the second screenshot.


It’s not nighttime (2:55pm), therefore the Milky Way arch is not displayed on the map.
At the end of the evening astronomical twilight (7:00pm), the Milky Way appears on the map.
  • Notice that the dots in the Milky Way arch have the same size. This is because neither the Core of the Milky Way nor the Galactic Center is visible yet.
  • When the Core begins to be visible, the dots in the Milky Way arch get progressively bigger, being the biggest dot the representation of the Galactic Center.
  • Due to I have the the world light distribution layer switched on, you've seen that the map has changed the color when I've moved time towards the night. When it's daytime, there is no color layer, but as you get into the golden hour, twilights and night, the map appears colored to help you assess the light you'll have. Now, I'll switch off the layer and most of the screenshots in this tutorial will appear uncolored , although I will be working during nighttime.

To better understand how the gray circumferences can help us assess the elevation of the arch, have a look at the following screenshots.

In the first screenshot, the center of the Milky Way arch is near the Observer’s pin, touching the circumference of 80⁰ of elevation. This means that the maximum elevation of the Milky Way arch is 80⁰ approximately, almost above our heads.

To get the exact number, drag the Galactic Center visibility information panel to the left. You’ll get to the Milky Way quality information panel (second screenshot). On it, you can read the Milky Way maximum elevation (second row): 80.7⁰.


Milky Way arch is high in the sky. Its center is touching the 8th circumference which represents an elevation of 80⁰.
Read on the Milky Way quality information panel the maximum elevation of the arch: 80.7⁰.
  • Have a look at the Milky Way picture that is on the Milky Way quality information panel (second screenshot). It’s showing you how you’d see the Milky Way if you where on the Observer’s pin position at 10:42pm on December 21st 2014. In this case, you’d see it pretty vertical. This is consistent with the Milky Way maximum elevation: 80.7⁰. It’s another feature that will help you assess how you’ll see the Milky Way in the Sky: horizontal (near the horizon), diagonal or vertical.
  • Near the Milky Way picture, you find the Milky Way Quality information bar, which takes into consideration the phase of the moon to help you easily find the best days to photograph the Milky Way: new moon days.
  • During new moon days, the bar is full, meaning you’ll have total darkness, the best conditions to shoot the Milky Way. The bar will be empty during full moons, when light conditions aren't good.
  • Tap once on the Milky Way picture and time will jump forward to the next best quality date to shoot the Milky Way. Double-tap on it to jump backwards to the previous best quality date to shoot it.
  • Finally, on this panel, you also get the azimuth (288.9⁰) and the elevation (-65.5⁰) of the Galactic Center for the Observer’s pin position and current date and time.

I recommend you to use the Night Augmented Reality view to double-check the Milky Way position in the sky.


South East - Night Augmented Reality view of the Milky Way. Notice that the Milky Way is pretty vertical.
North West - Night Augmented Reality view of the Milky Way.

We've also drawn the following picture to show you, approximately, the position of the Milky Way.

When you move time forward, the arch gets wider on the map as the center of the arch moves away from the Observer’s Pin (first screenshot), meaning that the Milky Way is getting lower in the sky, close to the horizon. In this case, the maximum elevation of the arch is 17.7⁰ (second screenshot).


Read on the Milky Way quality information panel the maximum elevation of the arch: 17.7⁰.

Again, the following Augmented Reality screenshots and picture will help you visualize how the Milky Way is represented on the map.


North East - Night Augmented Reality view of the Milky Way. Notice that the Milky Way appears to be pretty horizontal.
South West - Night augmented reality view of the Milky Way.
The same information represented on a picture. The maximum elevation of the arch is 17.7⁰.

With a single glance at the map, you’ll be able to understand the position of the Milky Way in the sky, its orientation (horizontal, diagonal, vertical) and visualize, as you move time forward/backwards, how it moves.

Remember that you can always use the Night Augmented Reality view to double-check that you get what you plan.

3 Milky Way And World Light Distribution Layer… When All Make Sense

When it comes to the Planner, all make sense… Let me prove it!

Move time backwards until is daytime, you’ll see the Milky Way disappear. Now, switch on the world light distribution layer by tapping on the button you find on the twilights information panel. Then, zoom out until you have a complete view of the light layer.

Now, move time forward to the end of the evening astronomical twilight, the exact moment PhotoPills considers the Milky Way to become completely visible. Notice that the Observer’s pin is just on the light line that separates astronomical twilight and night.

At this time, the picture of the Milky Way you see on the top information panel will become bright and the Milky Way arch will appear on the map.


The Milky Way is still not visible. The Picture of the Milky Way you see on the top panel is not bright.
At the end of the evening astronomical twilight, the Milky Way appears on the map.

Keep moving time forward and see how the Milky Way arch progressively fades, until it completely disappears.


At the beginning of the morning astronomical twilight, the Milky Way is still visible.

Having both, the world light distribution layer and the Milky Way, displayed on the map at the same time is very useful, for example, to visually find out when is the best time of the year to plan a trip to Iceland, in terms of Milky Way possibilities.

If you continuously change time starting on January 1 st 2014 and ending on December 31 st 2014, you’ll see how light conditions change throughout the year. You’ll realize that, from March to September, it is not a good idea to go to Iceland, because the Observer’s pin is never within the darker layer, it’s never nighttime!

4 Where The Milky Way Meets The Horizon: An Award-Winning Image

The white line connecting both ends of the Milky Way arch shows you the two directions where the Milky Way meets the horizon. This means that if you were on the Observer’s pin position, and looked towards both directions of the white line, you’d see that the Milky Way meets the horizon in these directions.

This line will help you plan any photo in which you wish the Milky Way arch to start or end in a determined direction, for example, aligned with a subject (lighthouse, rock, etc). It’s ideal for shooting panoramas of more than 180⁰ (horizontal) and capturing the whole Milky Way arch.

Have a look at the following example. Let’s align one of the ends of the Milky Way with the lighthouse of Nati (40.050513, 3.823813), in Menorca. Set the date to December 22 nd 2014 (new moon) and drop the Observer’s pin on a spot which leaves the lighthouse in the south.

Now, you only have to move time forward until the azimuth line of one of the ends of the Milky Way is aligned with the lighthouse, which happens at 4:21am on the 23 rd .


Milky Way arch at the end of the evening astronomical twilight.
Move time forward until one of the ends of the Milky Way (the white line) is aligned with the lighthouse, which happens at 4:21am on the 23rd.

Again, use the Night Augmented Reality view to double-check the Milky Way position in the sky.


Night augmented reality view showing you that the Milky Way begins just right from behind the lighthouse.

This is a representation of what you should get with a panorama:

I hope you realize how important this feature is. It is extremely useful to plan shots like Mark Gee’s winning image of the Astronomy Photographer of the Year 2013: Guiding Light To The Stars.

This is a spectacular view of the Milky Way arching over the coast of the North Island of New Zealand. I love the way that the Milky Way appears to emanate from the lighthouse – really cementing the connection between the stars and the landscape.

Have a look at the image, the central patch of light in the sky marks the Galactic Center, the bulge of stars at the heart of our Galaxy, 26,000 light years away.

Would you like to learn how to predict the Galactic Center, the central spot of the brightest area of the Milky Way? Keep reading!

5 How To Plan The Galactic Center


A representation of the lines that show you the range of directions (azimuths) where the Galactic Center will be visible.

The simplest way to understand how the Galactic Center information is displayed on the Planner, and how you can use it to plan a shot, is by having a look at an example.

Let’s see how you can use the 2D Milky Way Planner to find out the exact date and time the Galactic Center will be in front of the Naveta d’es Tudons (40.003128, 3.891558).

Drop the Observer’s pin near the Naveta and set the next new moon date (complete darkness). Remember that we always plan Milky Way shots happening during the new moon and the 4 days before and after it.

Let’s assume that you are planning this shot on December 12th 2014. Tap on the Milky Way picture you find on the Milky Way quality information panel to set December new moon date: 22 nd 2014. Shhhh. This is our secret short-cut to jump to next best quality day to shoot the Milky Way… Please don’t tell!


Assume that you start planning on the December 12th 2014.
Tap on the Milky Way picture you see on the top panel to jump forward in time to next new moon: December 22nd 2014

Go to the Galactic Center visibility panel (first screenshot). From this panel you learn that that the Galactic Center is always invisible. Thus, December is not a good month for shooting it. Let's have a look at the following new moon day. Again, tap on the Milky Way picture to land on January new moon: 20 th 2015.

Now, the visibility panel (second screenshot) is telling you that the Galactic Center will become visible at 6:16am (on the 21 st ) at azimuth 128.5⁰ when it is rising. Also, it’ll become invisible at 6:27am at azimuth 130.3⁰ and elevation 1.4⁰.


During December 2014 new moon, the Galactic Center will not be visible.
During January 2015 new moon, you’ll only have 11 minutes to shoot the Galactic Center.

Notice that the information you find on the visibility panel refers to the night between two consecutive dates: from the 20 th to the 21 st . This is the reason I know that 6:16am refers to the 21 st (morning) and not the 20 th .

Have a look at the two azimuth lines that have appeared on the map. The light gray line is showing the direction where the Galactic Center will become visible (azimuth 128.5⁰) and the dark gray one, where it’ll become invisible (azimuth 130.3⁰).

With all this information, You can get to the conclusion that, for this location, January is not a good month for capturing the Galactic Center. Although you’ll manage to see it, you’ll only have 11 minutes to enjoy it… and 6:16am is too early in the morning!

Let’s have a look at the February, March, April and May new moons and see how the visibility of the Galactic Center evolves.

During February new moon night, the Galactic Center will be visible for 1 hour and 43 minutes, starting at 4:18am (February 20 th ) and ending at 6:01am (February 20 th ). In March, the total visibility time is 2 hours and 52 minutes.


February 2015 new moon total visibility time: 1 hour and 43 minutes.
March 2015 new moon total visibility time: 2 hours and 52 minutes.

As you jump from month to month, you'll see how the total visibility time increases and the angle between the two visibility azimuth lines gets larger. During April new moon, the total visibility time is 3 hours and 54 minutes, starting at 1:30am (April 19 th ) and ending at 5:24am (April 19 th ). In May, the total visibility time reaches 5 hours and 2 minutes, starting at 11:32pm (May 18 th ) and ending at 4:34am (May 19 th ), which are very nice conditions for planning a Milky Way shot.


April 2015 new moon total visibility time: 3 hours and 54 minutes.
May 2015 new moon total visibility time: 5 hours and 2 minutes.

Let's stay on May 18th. If you set the time at 11:32pm (first screenshot), a white line will appear on the light gray visibility azimuth line. It’s the Galactic Center azimuth line. A bigger white circle, that represents the Galactic Center, marks the crossing point between this new azimuth line and the Milky Way arch. This way, you can easily distinguish the Galactic Center on the Milky Way arch.

Go to the Milky Way quality panel (second screenshot). Notice that the quality bar is full, meaning that you’ll have complete darkness. The Milky Way arch maximum elevation is 15.4⁰, the arch is low in the sky which is also confirmed by the Milky Way picture (pretty horizontal).

Also, this panel gives you the Galactic Center position for the selected date and time: azimuth 128.6⁰ and elevation 0.0⁰ (rise).


At 11:32pm, the Galactic Center azimuth line appears on the map.
The quality information panel displays the position (azimuth and elevation) of the Galactic Center numerically.
  • As you get near 11:32pm, you’ll notice how the white dots near the line, which connects both ends of the arch, suddenly get bigger and bigger, until the Galactic Center becomes visible.
  • The white dots on the arch start to get bigger when the core of the Milky Way starts to become visible.

Check now the night augmented reality view to have a better understanding of the position of the Galactic Center and the inclination of the Milky Way arch.


Galactic Center rise at 11:32pm May 18th 2015.

Move time a little bit forward to see how the Galactic Center moves on the map. The Galactic Center azimuth line is showing you its direction seen from the Observer’s pin location, for the selected date and time. Therefore, at 1:08am, reading the top panel (first screenshot), the Galactic Center will be at azimuth 145.6⁰ and elevation 12.1⁰.

At 4:34am, the Galactic Center will start to fade as we get into the morning astronomical twilight. Its position in the sky will be azimuth 191.5⁰ and elevation 20.2⁰.


At 1:08am, the Galactic Center is at azimuth 145.6⁰ and elevation 12.1⁰.
Galactic Center at the time it begins to fade: 4:34am.

You know all the basics now, let’s start the planning!

Remember, we'd like to find the right shooting spot and the right time to photograph the Galactic Center when is low in the sky and just in front of the Naveta. How to do it? Follow these simple steps.

First, set the time at 11:32pm on May 18th, right when the Galactic Center becomes visible, and check its elevation: 0.0⁰.

Second, on the Night Augmented Reality view, swipe your fingertip on the screen, from right to left, to move time forward until the Galactic Center has the elevation and position in the sky you desire. This happens at 1:33am on May 19th.


Galactic Center rise at 11:32pm May 18th 2015.
Galactic Center right where I want at 1:33am May 19th 2015.

Go back to the planner and check the elevation of the Galactic Center: 14.6⁰ (first screenshot). Now set the shooting spot. Drag and drop the Observer’s pin near the Naveta d’Es Tudons, in a way that the Galactic Center azimuth line is just in front of the ancient stone construction. This way, you’re choosing a shooting spot from where you’ll be able to shoot the Galactic Center when it is just in front of the Naveta.


Place the observer’s pin on a spot where the Galactic Center azimuth line is just in front of the Naveta.

And use the Night Augmented Reality view to check that the composition is right. As you see, it’ll be a great shot!


Check if you get the composition you want.

  • If you desire, you can adjust the composition by moving time directly on the Night Augmented Reality view.
  • If you want to test other possible shooting spots, just move the observer’s pin and repeat the same process.

6 Timelapsers! Galactic Center vs Milky Way Core visibility

The Galactic Center is displayed as a big red spot on the Night Augmented Reality view and the Core of the Milky way as a more realistic bright band.

If you plan to shoot a timelapse, you'll probably want to capture the rise of the Core. Therefore, you’ll need to assess when and where the Core will begin to appear above the horizon. This will happen before the rise of the Galactic Center and in a different direction (azimuth).

Thanks to the 2D Milky Way Planner and the Night Augmented Reality view, it is very easy to find out the exact time and direction the first stars of the Core will appear above the horizon level.

Let's move from the Naveta d'Es Tudons to the lighthouse of Artrutx, which is situated on the south coast of our island. Place the Observer's pin near the lighthouse.

Have a look at the first screenshot, it is 11:32pm, the Galactic Center is becoming visible at azimuth 128.5⁰. Notice that there are white dots of different size on the Milky Way Arch.

On the left-hand side of the arch, the dots are small and the same size. On the right-hand side, suddenly, the dots start to be bigger and bigger, meaning that the Core of the Milky Way begins to be visible. The right moment you see one of the white dots get bigger is approximately when the first stars of the Core become visible at the horizon level.

Therefore, move time backwards until the first big white dot appears on the Milky Way arch (second screenshot). This happens at 10:45pm. The white line that connects both ends of the arch is showing you the direction (azimuth) where Core is becoming visible.


It's 11:32pm, the Galactic Center is becoming visible.
The first bigger white dot tells you when and where the Core will start to appear above the horizon.

Using the Night Augmented Reality view is even easier to figure out. Just swipe your fingertips on the AR view, from left to right, to move time backwards, until you see the core appear above the horizon line.


The Galactic Center is rising and part of the Core is already above the horizon: 11:32pm.
The moment the core is appearing above the horizon: 10:45pm.

7 Video: Delicate Arch - Arches National Park (USA) - Galactic Center Visibility Evolution During 2015 - Northern Hemisphere

If you’re planning to go to the Arches National Park to hunt the Milky Way in 2015, have a look at this video and learn how the Galactic Center visibility time and direction change throughout the year at the Delicate Arch.

  • Total visibility time: 988.31 hours
  • Visibility peak: 5.63 hours, May 27th
  • Minimum visibility azimuth: 127.8⁰
  • Maximum visibility azimuth 232.2⁰
  • Hunting season:

8 Video: Cape Palliser (New Zealand) - Galactic Center Visibility Evolution During 2015 - Shouthern Hemisphere

I hope that those of you living in the Southern Hemisphere and, in particular, those living near Cape Palliser, enjoy watching how the Galactic Center visibility changes throughout 2015!


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