The first spectacular views of the sky from WISE

By Phil Plait | February 17, 2010 10:08 am

NASA’s fledgling Wide-field Infrared Survey Explorer (WISE) opened its eyes a few weeks ago, and astronomers have just released the first of a torrent of spectacular images from it.

Since its launch last December, WISE has been surveying the sky, taking data continuously as it spins on its axis and orbits the Earth. A few images have been released before, but these new ones are fully processed, scientifically-calibrated, and gorgeous.

I have to start with this one, because it’s just so pretty! Behold Comet C/2007 Q3, aka Siding Spring:


Holy dirty snowballs! That’s gorgeous, a classic comet. When this image was taken, on January 10, 2010, the comet was 340 million kilometers (200 million miles) from Earth. That’s a good ways off, so I’m impressed with the detail of this image! It’s actually a four-color image: blue is 3.6 microns (about 5 times the reddest wavelength the human eye can see, so well out into the infrared), green is 4.6, orange is 12, and red is 22 microns.

Since the temperature of an objects determines the kind of light it emits, we can estimate the temperature of the comet just by eyeballing this picture. It’s mostly orange, meaning the comet is pouring out light at 12 microns. A human being radiates infrared from about 7 to 14 microns, so this means the parts of the comet emitting IR (and therefore seen by WISE in this image) are around the same temperature as a person! Well, in physics terms; in human terms it’s pretty cold, about -40 Celsius. And it’ll get even colder now since it’s on its way out of the inner solar system, away from the Sun’s warmth. It’ll dim as it cools, too, returning back to invisibility once again.

WISE is expected to see quite a few comets, and in fact discovered its first just a few days ago. I wonder how many it’ll find, and if they’ll all be this pretty…?

Let’s take a step farther out for the next WISE image:


Recognize that galaxy? I wouldn’t blame you if you didn’t, but it’s Andromeda! That’s the nearest large spiral to our Milky Way. It’s roughly 2.9 million light years away (estimates vary) and can be seen by the naked eye from a dark site. This stunning photo really accentuates how amazing WISE is: the field of view is 5 degrees across, the width of ten full Moons. The Hubble camera I used to work with would barely cover a pixel in this image!

Remember, this image is all infrared. What looks blue here is actually cold stuff compared to what we’re used to: old red stars, for example. The colors are a little different than in the comet image, but red is still the coolest material: dust. These complex molecules are created when massive stars are born and when they die. Since massive stars don’t live long, they tend to die near where they were born, so you see the dust constrained to very narrow areas where star formation occurs. Less hefty stars (like the Sun) live long enough to drift away from their nursery over billions of years, so they fill the galaxy’s disk (in blue). That’s why the dust is so vivid and tightly defined in this image.

If you look closely, you can see the left side of the galaxy is a bit distorted. That’s called a warp, and is probably caused by a nearby pass of another galaxy, or one Andromeda actually absorbed. The fuzzy blob just below the main galaxy is a dwarf elliptical companion to Andromeda, orbiting it like the Moon orbits the Earth. It’s mostly composed of old stars that look red to our eye, so again it’s blue in this false color image.

OK, one more. I like this one a lot: NGC 3603, a star-forming region about 20,000 light years from Earth:

It may not look familiar, but if you’ve been reading my blog for more than a couple of weeks, you’ve seen it: I wrote about a Hubble image of this very nebula. Now, if you’re like me, you’ll click that link, look at the Hubble image, and then try to figure out where it fits in this WISE shot. Pbbbt. Don’t bother. The Hubble image is only a tiny portion of this vast vista, a blip right in the middle of the brightest part of the WISE image. The S in WISE is for "Survey", which means it takes pictures of ginormous swaths of sky, far more than Hubble can do. In fact, Hubble could take picture after picture for weeks and not get a view of the sky as large as WISE does in a few minutes (of course, the Hubble image would be a whole lot more detailed…).

In this image, as before, red is warm dust, and blue is hotter material like stars. The green is what gets me though: at 12 microns, that reveals PAHs, polycyclic aromatic hydrocarbons. These complex organic compounds form in cool conditions in nebulae, which are lousy with them. They’re everywhere where the temperature isn’t too high to disintegrate them. They can form even larger molecules, and some people think they may be important in creating the molecules necessary for life on Earth. That’s not to say those molecules form in nebulae like NGC 3603 and then somehow get here; they most likely form right here as well. The point is, they look like they’re pretty easy to make if conditions are right… on Earth as it is in the heavens.

And the sheer size and breadth of the nebula is simply stunning! I’m so used to narrow fields of view that I forget sometimes just how large these objects are. This nebula is dozens of light years across, forming thousands upon thousands of stars. It’s among the biggest such star factories in our galaxy, and is certainly easily visible from other galaxies as well. Even from 20,000 light years away — 1/5 of the way across our entire galaxy — it’s clearly a formidable object.

And that’s the strength of WISE. It can see large objects, investigate the bigger picture of the sky, and do it in the longest regions of the infrared spectrum, light that we simply cannot explore from the ground — our air absorbs it, and all the warm objects around us glow fiercely at those energies. It would be like trying to find a firefly against the Sun! So we must launch observatories into space to peer at the far infrared light from cosmic objects, and WISE will be our eyes to do just that.

And from these images it looks like it’ll do a fine job. I’m impressed with these images. I’ve seen a few early release observations in my time — I’ve made a few myself! — and these are excellent. The whole mission is only supposed to last a few months; there is coolant on board for the detectors that can only go so far. In that short time it has a whole sky to observe, and that’s a lot of space. But that also means there’s a lot to see: galaxies, asteroids, comets, nebulae… maybe even a gamma-ray burst or two. The next few months will be very exciting for infrared astronomy!

Related posts:
WISE uncovers its first near-Earth asteroid
First light for WISE
The terrible beauty of chaotic starbirth
Spitzer peeks under a cradle’s blanket

Images credit: NASA/JPL-Caltech/UCLA

CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (34)

  1. These colors are fabulous! “The Hubble camera I used to work with would barely cover a pixel in this image!” is that literally true?

  2. Very nice images and post Phil. I read your point on the WISE cooling running out soon and I have a question: the James Webb works in the IR as well. How do they plan to keep it cooled for the whole mission ? How does it contrast with WISE on this respect?


  3. ethanol

    Wait… polycyclic aromatic hydrocarbons? So radiation isn’t the only way that space gives you cancer? Nice.

  4. Byron

    Awesome pics!!

    Can you elaborate a little bit on “around the same temperature as a person! Well, in physics terms”? I am a little confused by this. If a human radiates 7-14 microns and and 12 microns=-40 degrees, that would seem to imply people can be even colder. But obviously people can’t have a body temp that low. What am I misunderstanding?

  5. “but it’s Andromeda! ”

    That’s Andromeda!?! Wow, this thing does take cool pictures!

  6. Question, Phil: When WISE discovers new comets, will they be called Wise 1…Wise 2…etc. ?

    What a wonderful and dynamic set of astronomical pictures to start off the day with.

  7. Scott

    Great post, man. Very interesting stuff.

  8. Phil,

    Could you explain if WISE will serve as any sort of replacement for Hubble going forward? These images seem pretty amazing and reminded me of Hubble pics.

  9. LightPhoenix

    If I recall correctly, the coolant is used because otherwise the camera is too warm and will in essence blind itself, correct? Would it still be possible to take brief images by letting space cool WISE?

  10. philippec

    What happens to WISE after the coolant is all expended? Will it be thrown in the atmosphere, or can it still be used for other stuff?

  11. Steve Paluch


    Please never stop posting your thoughts on this stuff, because it is invaluable. Your train of thought is the same type that got me interested in astronomy back in the 80’s.

  12. Doug

    “Well, in physics terms; in human terms it’s pretty cold, about -40 Celsius.”

    Strange … my calculations show that it should be -40 Fahrenheit…

  13. Doug

    “WISE is expected to see quite a few comets, and in fact discovered its first just a few days ago. I wonder how many it’ll find, and if they’ll all be this pretty…?”

    Does this mean the end of amateur comet hunters? I sincerely hope not.

  14. Wow, what a bunch of WISE Skies!

    (should have been your title)

    – Jack

  15. Messier Tidy Upper

    ^ LOL. :-)

    Saw this as an on-line news image gallery and was just about to post the link :

    to the BA when I came here and found he’d beaten me to it. 😉

    @ 14. Doug Says:

    “WISE is expected to see quite a few comets, and in fact discovered its first just a few days ago. I wonder how many it’ll find, and if they’ll all be this pretty…?”

    Does this mean the end of amateur comet hunters? I sincerely hope not.

    Hope not & I don’t think so – although it does give the amateurs some tough competition just like SOHO ( ) and LINEAR ( ) have.

  16. Messier Tidy Upper

    Have to scroll down a way to see it but the Solar and Heliospheric Observatory site notes :

    As a consequence of its observing the Sun, SOHO (specifically the LASCO instrument) has inadvertently discovered comets by blocking out the Sun’s glare. Approximately one-half of all known comets have been discovered by SOHO. Recently, it discovered its 1,500th comet.

    Whoa! One thousand five hundred. That’s a lot of sun-grazing comets! :-)

    Guess between that and LINEAR and now WISE it is getting much tougher for the amateur comet-hunters. But still not impossible – just tougher. :-(

  17. Timmy

    ” it takes pictures of ginormous swaths of sky,”

    How many zeros is that?

    More than a bunch, I’ll bet.

  18. Marshall P

    For those readers asking about WISE’s future: This has always been planned as a very short-term mission, but one so efficient that it can map the *entire sky* before its hydrogen coolant runs out. So we will have images of this quality for literally everything in the heavens (well, apart from inner solar system objects like Mercury and, um, the Sun. But everything else!). Like Spitzer, once the coolant runs out the longer wavelength channels will be unusable, but it could keep going for deeper mapping on the shortest wavelength ones.

    But really, the true value of WISE is going to be the treasure trove of data that it’s collecting. In the 9 months of the active mission, there’s no way we can even scratch the surface of analyzing and interpreting what is found. The WISE maps and catalog are going to be mined for new discoveries for decades to come!

    In particular, the payoff is going to get even better once JWST launches. WISE gives the big picture in the IR now, then starting in 2015 JWST can zoom in far closer (even closer than HST can!) to examine the details of all the most interesting new discoveries. It’s a perfect pairing. (And as for the question about how JWST can stay cool, it’s going to use an amazing and complex system of reflective sunshades, larger than a tennis court, to keep the scope hidden from the sun. No coolant to run out, but that sunshade alone will cost significantly more than what the entire WISE mission does! )

  19. Marshall P : Thank you very much for the clarification

  20. DLC

    Dammit Phil what’s with all the non-skepticism posts! you’re clouding things up with all this Science! (/inverted concern troll)
    seriously though, those are some great pictures, thanks for posting them.

  21. Thanks for the great pictures. My 3 year old son can not get enough. Thanks for helping grow his imagination.

  22. Brian137

    Absolutely gorgeous. My favorites are Andromeda and NGC 3603.

    O twice trumped comet!
    O incandescent snake!
    Thy beauty delights,
    But magnificence reigns.

  23. #4 byron – i’ve known some people who ARE that cold 😉

  24. These are gorgeous. I love the colors that WISE captures.

  25. I thought it was going to be a few boring old post, where it undeniably compensated for my day. I will post a link to this page on my blog. I am certain my visitors will discover that extremely realistic


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