The Helix has pink eye

By Phil Plait | October 4, 2012 7:00 am

One of the most amazing objects in the sky is the Helix Nebula, an expanding cloud of gas and dust surrounding a dying star. This type of object is called a planetary nebula, and it’s formed when a star a bit more massive than the Sun turns into a red giant and blows off its outer layers. These expand away, and eventually the hot core of the star is exposed. This floods the gas with ultraviolet light, causing it to glow pretty much like a neon sign*.

The Spitzer Space Telescope and GALEX combined their forces to observe the Helix Nebula, and what they see is simply stunning:

Oh my. [Click to ennebulenate, or grab a 6000 x 6000 pixel version.]

GALEX sees in the ultraviolet, so it’s sensitive to the light coming from the central star and the hot gas reacting to it (colored blue in the picture). Spitzer sees in the infrared, so it detects warm gas and dust (red, yellow, and green). Where you see pink is where the nebula is emitting both IR and UV. [Note: some of the outskirts of the nebula were beyond Spitzer’s field of view, so images from the infrared observatory WISE were used there to match the GALEX field.]

One of the most interesting features of this nebula is the collection of long, comet-like "fingers" you can see throughout the structure. These are where denser clumps of material are boiling away under the intense UV radiation of the central star, blowing out long tails away from the center like spokes in a wheel. Some of those tails are trillions of kilometers long!

Despite being one of the closest planetary nebulae in the sky – a mere 700 light years away – I’ve never seen the Helix through a telescope. Why not? Because it’s so big! The light from the gas is spread out over an area in the sky the size of the full Moon, dimming it considerably. Maybe someday I’ll be at a dark site with a big ‘scope, and I’ll see this fantastic bauble with my own eyes… but it won’t look like this picture. Our eyes see only a small slice of the electromagnetic spectrum. They serve us well in our daily lives, but the Universe itself sends out information in every direction to which we’re blind.

That is, until we used our limited brains to build devices like Spitzer and GALEX that expanded our viewpoint. And that’s what science does: removes the scales from our eyes, allowing us to see what the cosmos itself is showing us.

Image credit: NASA/JPL-Caltech

* I’m simplifying here a bit. If you want more in-depth info on what happens as a star like this dies and glows like some great gaudy celestial Christmas ornament, read this post about the Helix I wrote a while back.

Related Posts:

Down the throat of a dying star
The Helix screams in the infrared
A warm anniversary for Spitzer
The Helix’s dusty heart


Comments (13)

  1. PatrikH

    >>Maybe someday I’ll be at a dark site with a big ‘scope, and I’ll see this fantastic bauble with my own eyes…

    I’d actually recommend a medium scope (around 10-12″) at the lowest magnification possible and IIRC an OII filter. In our 17″ scope the Helix nebula is so large that it looks like reverse vignetting, the field of view gets a bright edge and a dark center. We have to move the telescope around to see the entire thing.

  2. Hey, it’s the Eye of God!

    Clearly, proof positive that Archbishop Ussher was right: the univese is only 6016 years old.

  3. Wzrd1

    @rastronomicals, in a relativistic way, that IS possible. 😉
    Though incoming hard gamma radiation would most likely ruin one’s trip through the universe.

  4. ozprof

    It is quite easy from the southern hemisphere. It looks fantastic in a 17″ easy in a 5″ and 80mm binoculars, and if the sky is dark, visible to the naked eye. No filters needed. From my dark-sky site, I used it as a guide to the seeing. If it was not visible to the naked eye, the conditions were poor.

  5. OneofNone

    How does this picture compare to the APOD from today?

    The orientation seems a bit different, turned by several degrees. Turning the APOD about 120 degrees clockwise seems to get a match. The colour mismatch is … fascinating?

  6. sebastian

    Oh, you could SO colour this to look like the Eye of Sauron.

  7. Regner Trampedach

    OneofNone @ 5: So the silly guys at NASA can’t even figure out which way is up… Oh, wait! :-)
    Cheers, Regner

  8. CatMom

    Re: Rastronomicals “Eye of God”

    If it *is* the Eye of God, then He has a rather nasty case of conjunctivitis. 😛

  9. VinceRN

    Every time you post pictures like this I want to go out to the garage, show them to my telescope, and kick it.

  10. Nick L

    “The Helix has pink eye”

    Ben Stein has his work cut out for him.

  11. @6. sebastian :

    Oh, you could SO colour this to look like the Eye of Sauron.

    Yes – but it still wouldn’t match Sauron’s eye quite as closely as Fomalhaut’s protoplanetary disk does! 😉

    (See link in my name here – “Hubble spies lord of the stellar rings” New Scientist – to see what I mean! )

  12. Jess Tauber

    We wouldn’t have to remove the scales from our eyes if it weren’t for our Reptilian brain.

  13. JB of Brisbane

    Expect a phone call from Endemol’s legal team any time soon – for using the Big Brother logo without their permission.


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