SUNSET: 
12If you’d like to roam the entire celestial sphere virtually, check out a new collection of downloadable high-resolution images of all 88 constellations.
Anyone who enjoys looking at star maps from long ago soon realizes that the concept of “constellations” was applied rather loosely, depending on the whims of each cartographer. And over time some constellations were proposed but never caught on — or were later abandoned. (Check out Bob King’s amusing look at some of these.)
It wasn’t until 1922 that the International Astronomical Union agreed on a list of 88 constellations, drawn from Western traditions, to cover the entire celestial sphere. Six years later the IAU adopted precise boundaries for each one that were published in 1930.
These days, even seasoned starwatchers would be hard pressed to name most of the constellations, in part because those of us at mid-northern latitudes can’t see the ones in the far southern sky and vice versa. For example, someone living at latitude 40° north has no chance of seeing any of the night sky south of declination –50° (ignoring atmospheric refraction). This geometry renders 14 constellations completely hidden and another 15 only partly in view throughout the year.
But that shouldn’t stop you from being curious about both the well- and lesser-known constellations that fill the sky. And now you can explore them any time, thanks to a new online resource launched this week by the National Science Foundation’s NOIRLab in partnership with the European Space Agency.
NOIRLab / NSF / Eckhard Slawik
The 88 Constellations Project brings together several resources. Most impressive is a complete set of downloadable high-resolution images acquired by German astrophotographer Eckhard Slawik. His images, recorded on film, combine exposures with and without a diffusing filter to allow the stars’ colors to shine through — a technique pioneered by the late Akira Fujii. Slawik has also combined his individual frames into an all-sky image that lets you navigate around and zoom in on any location.
The entry for each constellation includes a comprehensive description and its historic origins, as well as the stick figures and finder charts (created in partnership with Sky & Telescope). Also available are images and descriptions of each constellation’s most prominent deep-sky objects.
As you explore what’s available at NOIRLab’s 88 Constellations Project, don’t forget that other websites also offer excellent introductions to the sky. One example is Iacopo Sassarin’s theskylive.com, which lets you know whether a given constellation is currently visible from your location. (Do you have others to suggest? Then add a comment below with the links.)
And of course, don’t forget Sky & Telescope’s interactive sky chart, which you can customize for any location, date, and time.
About J. Kelly Beatty
J. Kelly Beatty, S&T Senior Editor, joined the staff of Sky Publishing in 1974 and specializes in planetary science and space exploration. Learn more about him here.
Comments
Lou
December 26, 2024 at 5:21 am
Such an excellent resource, cheers for the heads up!
You must be logged in to post a comment.
Anthony Barreiro
December 26, 2024 at 8:03 pm
This is indeed an excellent resource, thanks!
I've always found the official far southern constellations uninspiring. They have no traditional lore. During the 16th to 18th centuries individual European astronomers played connect the dots in a sky they were seeing for the first time, which their ancestors had never seen. Europeans colonized the southern sky just as they colonized the land. The early modern European astronomers seem to have been blissfully ignorant of how the Indigenous peoples of the southern continents and islands understand and relate to the sky. I wish the IAU would put together a work group to figure out a more culturally and historically respectful system of southern constellations.
You must be logged in to post a comment.
Frank-ReedNavigation.com
January 4, 2025 at 9:54 pm
Anthony, when they re-draw the southern constellations following your suggestion here (or many similar ideas over recent decades), I hope that they will squeeze in the constellation "Calix Vermibus" --the proverbial "Can of Worms". 🙂 You suggest that the "southern constellations should be re-done. So then, everything south of the celestial equator?? Or just that southern zone that we who control the skies graciously ignore from our mid-northern latitudes? Or do you mean every part of the sky visible to observers south of the Earth's equator (which would mean the entire sky, since observers just south of the equator actually see the whole thing!). See what I mean about "can of worms"? And just which culture should have the sky re-drawn by the IAU using its unique constellations? How many indigenous cultures are there worldwide?? Do they all get "Latin-ized" as a measure of our pseudo-classical respect? And why stop with the southern sky? Who needs the northern constellations "Lacerta" or even "Aries"?! Let's ditch those. Or better yet, why in the world do we have two triangle constellations, "Triangulum" in the north and "Triangulum Australe" in... well, it's right there in the name. And don't forget there used to be a third: the fabulously un-necessary "Triangulum Minus". And if we're going with shapes as trivial as triangles, why not make the "Summer Triangle" a proper constellation?? We can keep the wings of Cygnus and Aquila for legacy, and let's face it, no one will miss Sagitta or Vulpecula or even Lyra! The Summer Triangle is the ONE triangle that shall rule them all... Oh, and don't get me started on "Equuleus" (hmmm... too late...). Why does the big horse, Pegasus, need a little buddy that's barely visible? Let's toss Equuleus, too.
On the other hand, the IAU has made efforts to add some indigenous star names to the list of "official" IAU star names that have been declared starting in 2016 (like Paikauhale and Gunnibuu, for example). So it's possible to make small steps in the direction you're suggesting. Are these very small steps "better than nothing" or might they be even worse than nothing? One southern case that deserves some discussion: the constellation "Indus" (the Indian). It's embarrassing to astronomy broadly. Maybe we could make it into another snake constellation. Sure, we have Draco, Serpens (head and tail), Hydra, and Hydrus constellations --all snakes and serpents-- and Perseus is holding the snake-covered head of the Medusa, but is that enough? We need more astro-snakes, don't we?? Nah, I'm just kidding... We have a surplus of astro-snake constellations. But Indus might be a good choice to rename and re-identify. It's a perfect new home for my "Calix Vermibus". Let's start there. The rest can wait for another century.
Frank Reed
Clockwork Mapping / ReedNavigation.com
Conanicut Island USA
You must be logged in to post a comment.
jcsch
December 27, 2024 at 9:33 am
Download fails to complete with "a few seconds left"
You must be logged in to post a comment.
Bill Gray
December 28, 2024 at 9:02 pm
For an alternative view as to how the IAU came up with the 88 official constellations, including "the Irish constellation" O'Ryan :
https://www.newyorker.com/magazine/2017/05/01/the-irish-constellation
You must be logged in to post a comment.
ToomasKarmo
December 29, 2024 at 12:59 pm
(1) The _Sky and Telescope_ maps which the NOIRlabs team uses as accompaniments to its constellation photos are useful, showing as they do the Bayer letters for individual bright stars. I personally find that Bayer letters help me populate the sky with sounds, thereby supporting the memory: Corona Borealis becomes "thbagdei" (theta-beta-alpha-gamma-delta-epsilon-iota), the wings of Cygnus become "egd" (epsilon-gamma-delta), Orion's belt becomes "zed" (zeta-epsilon-delta), and so on. Is anyone apart from me trying this Bayer-phonemics trick, for instance in public outreach work?
(2) It would be good for someone, whether at NOIRlab or at _Sky and Telescope_ or at some other astronomy-outreach establishment, to comment at some stage on the vexed question of pronunciation. NOIRlab gives traditional pronunciations of constellation names without, so far as I see on rapid inspection, more detailed comment. But there is a problem. Constellation names tend to be in Latin. The pronunciations common in the English-speaking astronomical world tend to be idiosyncratic English pronunciations, not faithful to actual Latin pronunciation from the high point of Roman civilization (in other words, from the literary epoch that includes Cicero and the epic poet strictly styled "Virgil", in the Anglo world often more loosely styled "Vergil": this is the epoch which everyone, all through the past two millennia, has rightly taken as normative for Latin syntax). Latin pronunciation has been studied with due care since the time of Erasmus, after suffering approximately one millennium of neglect. It has since Erasmus's time been clear that, for instance, "Coma Berenices" is not the "CO-ma bare-uh-NYE-sees" offered by NORIab, but "CO-ma bare-uh-NEE-kes". Although we cannot hope to enforce correct Latinity, it would be good to see astronomy publishers somewhere stating that their offered pronunciations for Latin constellation names do not reflect accepted best scholarly practice, as promulgated in university Classics Departments (ultimately, these days, from such accepted university authorities as Sidney W. Allen's book _Vox Latina_) - that they instead reflect a phonemically degenerate Latin, stemming from unreformed post-classical times. (Well, stemming ultimately from one of the post-classical "national pronunciations" which bedevilled Erasmus and his Renaissance contemporaries, as they tried to clean up an inherited mediaeval philological mess: but that detail need not be belaboured in astronomy publications. Erasmus and his contemporaries found that Latin pronunciation had drifted in various disparate directions, making it hard for, e.g., an Italian to converse intelligibly in Latin with a Briton. This was reeeel bad, since Latin was supposed to be the language of international exchange.)
(3) While the _Sky and Telescope_ stick figures, as reproduced with those so-useful Bayer letters at the wonderful new NOIRlabs constellations project, are helpful, a question does arise: why those particular sticks, rather than the sticks used by _Sky and Telescope_ in its sky-this-month centrefolds back in the 1980s or 1990s (or thereabouts)? The old centrefolds were the creation of a thoughtful and careful celestial cartographer, George Lovi (who died in 1993, according to Wikipedia). Why the new sticks, rather than the late Mr Lovi's sticks? Sometime the differences are rather pronounced, as with the northernmost part of Serpens Caput. - Personally, I value Mr Lovi's work to the extent of having a decade or two ago photocopied his centrefolds for January, May, and September, and having had those photocopies laminated. Since his sticks are rationally placed, and are not too hopelessly numerous (in other words, are not too hopelessly cluttered), and since Mr Lovi puts in Bayer letters, those three laminated sheets have become my rather constant companions. I take them out with me pretty regularly to our local amateur-astronomer plaza, a few tens of metres from the 1.5 m reflector here at the Tartu Observatory dark-sky campus (in south-central Estonia, at 58o16' N, 26o28' E). Is there some reason for the departure from Mr Lovi's tradition at the _Sky and Telescope_ of the 21st century, or is this one of those things that have just happened, in a random kind of way?
You must be logged in to post a comment.
Andrew James
December 30, 2024 at 6:38 pm
Awful.
Constellation boundaries in these pictures all seems to be slightly, especially as we don't know what Epoch it is set. e.g. 2000 or 2024?
There are also no indication of scale, eg. Hydra, Eridanus & Cetus a smaller in scale than some of the other constellations. A casual observer would think that, say Chameleon, it's just as big as the two big constellations. All three would be better divided in half, either the north-south portions or east -west portions.
There are also a lot of photographic distortions, very odd shaped stars depending on which part of the frame you look at. If you look along the Apus and Octans, for example, multiple images of these two constellations are plainly different in several of the presented images.
Moreover, the colour correction and the wavelengths of the images aren't given, and the images seem far less red compared to human eye. Also the saturation seems far too blue.
The magnitude limit also looks a little bit suspect between each group of images of constellations.
Even the dark nebulae doesn't look right, with some seemingly issues with contrast.
It's a good attempt, but I think it could be done with a better and more careful detail.
Note 1: I really like the Sky and Telescope maps, but the outline of the constellations I always found debatable, especially for the southern ones. For example, Musc ais missing its entire left wing along theta Mus and m Centauri on in the direction going towards Beta Centauri. Also Chameleon is missing the line between delta and theta Cha. In most texts and constellation outlines commonly used, these lines are always there, but for some reason, they have been discarded
Note 2: Splitting up the large-sized constellations in halves would help. More equal sizes would help create better printed sky maps or when displaying constellations on digital screens. Both parts are, perhaps, best divided by their Latin terms. We should use the words like Hydra Orientus (West) & Hydra Occidens (East) or Eridanus Supernus (North) & Eridanus Improbus (South.) These are subconstellations. [As the names ‘Australis’ and ‘Borealis’ are already used for several north and south constellations - so they can’t be used.] This could be applied to constellations like Aquarius, Bootes, Camelopardalis, Carina, Centaurus, Cetus, Cygnus, Draco, Hercules Leo, Pegasus, Puppis, Sagittarius, Ursa Major Vela & Virgo. Doing so would make each constellation a little bit more equal in area, reducing the majority of constellations to each be between 400 and 600 square degrees or less.
Note 3 : Hydra may be finally halved by Right Ascension, making two segments more logical instead of being spread over 7 hours RA or one-third of the entire sky’s circumference. Hydra segmented along 11-hour RA in Epoch 1875.0 makes two more sensible pieces of nearly equal size, changing Hydra’s area from about 1303 deg^2 into about 713 deg^2 for Hydra Occidens (East) and 590 deg^2 for Hydra Orientus (West). These are far more manageable pieces and are similar now to Andromeda or Orion in size.
You must be logged in to post a comment.
Andrew James
December 30, 2024 at 6:41 pm
Correction: "Constellation boundaries in these pictures all seems to be slightly off, especially as we don't know what Epoch it is set. e.g. 2000 or 2024?" Sorry.
You must be logged in to post a comment.
Bill Gray
December 31, 2024 at 10:44 am
Constellation boundaries were specified in 1930, and follow lines of RA and dec for the epoch B1875.0. As you note, that looks significantly askew from the J2000.0 grid (a 41' offset).
As I recall, the main criterion for setting the boundaries was that already-designated variable stars stay in their designated constellations, resulting in the twisty maze we have now. I don't know if similar efforts were made for Bayer and Flamsteed-designated stars. They did end up, for the most part, in the "correct" constellation, but I could imagine that having happened simply as a result of contorting the boundaries to accommodate designated variables.
You must be logged in to post a comment.
Andrew James
December 31, 2024 at 7:10 pm
Thanks. No. The current boundaries in the images are noticeably slightly skewed to the fixed positions for each point on the celestial sphere as determined by Gould in B1875.0. They calculated the precession for each of these points has been made, but to what Epoch? The lines on the images don't seem to exactly align with the accept boundaries. It's hard to explain why this happened.
You must be logged in to post a comment.
Frank-ReedNavigation.com
January 4, 2025 at 9:18 pm
Andrew, where do you see any "skewing" of the constellation boundaries? I checked Ursa Minor and Libra just now. The constellation boundaries are just where they should be as far as I can tell --dead on. I'm sure many reading this comment are aware that the constellation boundaries are essentially fixed relative to the distant stars. But for those unfamiliar... Precession shifts the coordinates of the stars, and it shifts the coordinates of the constellation boundaries in just the same way. There is a popular "myth" among many astronomy enthusiasts which imagines the stars precessing out of their original constellations. This doesn't happen. Only the extremely slow effects of proper motion can accomplish that, and with rare exceptions, that takes time on the order of a century for a very few cases at the low end and more typically thousands of years.
I would add that I agree that there are many problems with these constellations "guides" and the semi-photographic images that illustrate them, but the constellation boundaries are not among those many problems. 🙂
Frank Reed
Clockwork Mapping / ReedNavigation.com
Conanicut Island USA
You must be logged in to post a comment.
Andrew James
January 8, 2025 at 3:34 am
Good point. You need to look at the celestial poles to see the problems. I know the details of the boundaries, so I know better than most. I have a paper coming out very soon about this, I know the history of how these boundaries were determined, including variables. Thanks for your response.
You must be logged in to post a comment.
You must be logged in to post a comment.