Two nearby galaxies peek out through the dust

By Phil Plait | March 9, 2010 7:26 am

NASA’s Wide-field Infrared Survey Explorer, or WISE, only launched a couple of months ago, and has already done spectacular work. Gulping down huge tracts of sky every day, it has already discovered over 2000 asteroids — not seen, but actually discovered — including several that pass near the Earth (none on track to hit us, happily). It’s discovered four comets, too, and by the end of the mission in a few months will see far more.

But since it’s a survey instrument, and it sees in the far infrared, the views it gets are nothing short of spectacular! Like this one:


[Click to embiggen, or grab this ginormous 11,000×4000 TIF].

There is a lot to see here! First, the colors: all of this is far infrared, with blue being the IR wavelengths of 3.4 and 4.6 microns combined (5 and 6.5 times the wavelength the human eye sees), green is 12 microns, and red 22. Green is dominated by warm dust and big organic molecules called polycyclic aromatic hydrocarbons.

The glowing gassy stuff is part of the Heart Nebula, which I’ve posted about before (guess what date). But take a look a bit to the left of all that gas, and look much, much farther in distance…


Those are two galaxies, called Maffei 1 and 2. Both are actually quite close to the Milky Way, only about 10 million light years away. They’re big galaxies, and really should be among the brightest galaxies in the sky. Yet chances are you’ve never heard of them! That’s because this area of the sky is loaded with dust in our galaxy, which absorbs visible light. Another incredibly beautiful galaxy, IC 342, is also part of that group, but is hard to see in visible light as well.

Maffei 1 is right and below center, and Maffei 2 is the barred spiral one above it. For comparison, this image here is about twice the diameter of the Moon on the sky. WISE has a huge field of view, so it doesn’t get high-res images of galaxies, but it more than makes up for it in breadth and depth. Observations like this will help astronomers map the dusty content of nearby galaxies, and even get a handle on how much dust is in much more distant galaxies, though the maps won’t be quite as detailed. Still, more information is always good, and getting to study galaxies — and nebulae, and planets, and comets, and asteroids, and and and — in the far infrared will help our understanding of all these objects far better.

As an aside, I learned of this image on my pal Amy Mainzer’s WISE blog. She’s a bigwig with WISE, and when she has time away from doing nonstop firehose science she writes up fun stuff about this new and extremely cool spacecraft. That’s definitely one you want to drop into your RSS feed reader!

CATEGORIZED UNDER: Astronomy, Pretty pictures
MORE ABOUT: asteroids, galaxies, WISE

Comments (18)

  1. Messier Tidy Upper

    Guess what – I had actually heard of Maffei I & II before – but never seen them like that! :-)
    Part of the Local Group & less well known but significent major members of that along with our Galaxy, Andromeda (M31) and the Triangulum or Pinwheel Galaxy (M33) aren’t they, right?

    Great image & a very WISE choice there BA. ūüėČ

    Four comets & 2,000 asteroids – thats great, I remember reading about WISE’s first cometary discovery here (& I saw its launch on NASA TV via here too)– but what I’m really keen to hear is how WISE is going as far as finding brown dwarfs – potentially one closer than Proxima Centauri? No luck there yet? I guess we’ll hear when there’s news right?

  2. Phil, wondering if you had a chance to check out this new abstract from the Center of Astrophysics and Space Astronomy: . The paper discusses the development of a IR laser comb that could improve RV detection precision by 2 orders of magnitudes, enabling astronomers to detect Earthlike worlds around Sol-like stars. If you are familiar with the paper, could you perhaps expand on the subject?

  3. Douglas Troy

    Great post Phil. Amazing pictures and the bits of information you provided about WISE were very intriguing. It’s incredible to think that it has discovered 2000 asteroids in the short time it’s been up there.

    Man I love this science stuff.


  4. Plutonium being from Pluto

    From my old notes for the Adelaide (Mawson Lakes) planetarium, South Australia :

    The Local Group ‚Äď Our Milky Way Galaxy, Andromeda, Triangulum and the Magellanic Clouds along with other local galaxies form the Local Group of nearby galaxies. These include roughly thirty galaxies of all major types that share a common motion through space and extend out some four million light years. Most are small dwarf galaxies with the lenticular (SO type) galaxy Maffei I making up the last of the large galaxies after Andromeda, our Milky Way and Triangulum. Maffei I was discovered by the Italian astronomer, Paolo Maffei, as an infrared source in 1968.

    I believe the main source for this was :

    Henbest, Nigel & Couper, Heather, The Guide To The Galaxy, Cambridge University Press, 1994.

    For more info & WISE images – incl . related links on WISE via the BA blog see :


    Among the related links is its first asteroid discovery – see :

    Or just click the hypertextual WISE tab after today’s date & before the “by Phil Plait” that got me that … ūüėČ

    I love this mission! Congratulations to the WISE guys. 8)

  5. This was today’s APOD too. It’s a conspiracy I tell you!

  6. Mike C.

    Who needs new age pseudoscience when we’ve got this cool stuff? And it’s real too! Thanks for the super pics and links.

  7. I really need to get a bigger monitor.


    @ Matthew,


  9. DrFlimmer

    I guess, we are finding lots of targets for JWST, aren’t we?

  10. ” That‚Äôs because his area of the sky is loaded with dust in our galaxy, which absorbs visible light”

    aww man.. when did you get all religious?

  11. Chris A.

    @#1 & #3:
    The current thinking is that Maffei I and II are actually NOT part of the Local Group, but are part of a separate group (known as the IC342/Maffei Group).

    Also, I’ve seen Maffei I described as both a “giant elliptical” (closest one to the Milky Way) and a lenticular (S0 pec) by various sources.

  12. Andrew

    Ah, the Zone of Avoidance! Also Dwingeloo 1 and 2.

  13. Jya Jya Binks Killer

    @10. Chris A. Says:

    @#1 & #3: The current thinking is that Maffei I and II are actually NOT part of the Local Group, but are part of a separate group (known as the IC342/Maffei Group). Also, I‚Äôve seen Maffei I described as both a ‚Äúgiant elliptical‚ÄĚ (closest one to the Milky Way) and a lenticular (S0 pec) by various sources.

    This is what Wikipedia says too :

    Maffei 1 is an elliptical galaxy in the constellation Cassiopeia. It is the closest giant elliptical galaxy to the Milky Way. Once believed to be a member of the Local Group, it is now known to belong to the IC 342/Maffei Group. It was named after Paolo Maffei, who discovered it and the neighboring Maffei 2 in 1968 from their infrared emissions. Maffei 1 might have two possible satellites (MB1 and MB2).


    “The IC 342/Maffei Group (also known as the IC 342 Group or the Maffei 1 Group) is the nearest group of galaxies to the Local Group. The group can be described as a binary group; the member galaxies are mostly concentrated around either IC 342 or Maffei 1, both of which are the brightest galaxies within the group. The group is one of many located within the Virgo Supercluster (i.e. the Local Supercluster)”

    Of course, being internet rather than a science paper or book source means this perhaps may not be 100% reliable & could be taken with a pinch of salt but Wikipedia seems pretty good & consistent here, right?

    Hmm …The picture there looks familiar too – that didn’t take long! ūüėČ

    PS. This is also today’s Astronomy Picture Of the Day :

  14. andy

    Wikipedia hedges its bets on Maffei 1, describing the galaxy as a “giant elliptical” but giving its Hubble classification as S0 (i.e. lenticular) in the associated infobox.

  15. Plutonium being from Pluto

    @ 10. Chris A. Says: (& # 12 Jya Jya Binks Killer concurs along with Wikipedia etc ..)

    @#1 & #3 (now 4 post moderating- ed) : The current thinking is that Maffei I and II are actually NOT part of the Local Group, but are part of a separate group (known as the IC342/Maffei Group).

    Okay, looks like I need to revise those planetarium notes then. Interesting – thanks. :-)

    – Plutonium being from Pluto aka StevoR.

  16. Brian137

    Thank you, Phil.

  17. As a toxicologist, I read polycyclic aromatic hydrocarbons and got all fuzzy inside. Do you know which PAH molecules dominate these clouds?


    @ JohnTR,

    According to this paper, “Estimated IR and phosphorescence emission fluxes for specific Polycyclic Aromatic Hydrocarbons in the Red Rectangle” [PDF], the spectra of the hydrocarbons anthracene (C14H10), phenanthrene (C14H10), and pyrene (C16H10) have been observed in the Red Rectangle Nebula.

    So, it’s probably the same in the Heart Nebula featured above.


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