GLIMPSE The Galaxy

8 06 2008

So if you don’t know about the Spitzer Space Telescope let me take a moment to tell you about it.


It is the last of the four space-based telescopes in Nasa’s Great Observatories Program. The others included the Hubble Space Telescope, the Compton Gamma-Ray Observatory, and the Chandra X-Ray Observatory. Each one sees a different part of the spectrum. Spitzer sees in the infrared, specifically wavelengths between 3 and 180 microns. Whereas the other telescopes can see parts of the spectrum we *mostly* can see from the ground, our atmosphere blocks almost all of the infrared light. When we look at the sky in the visible spectrum, much of our galactic view is blocked by dust and other particles. Infrared light has a long wavelength (relatively speaking) and isn’t stopped by these particles. That means we can peer through the stuff that’s normally in our way and see what’s behind it. So this instrument is really important, and is delivering images that you can’t get anywhere else.

Speaking of images, here’s the reason for this post. The science team at Spitzer has just released a composite of 800,000 images of the Milky Way this past week. That’s a huge composite! In fact, it’s so big that if you tried to print it out at full resolution the picture would be 180 feet long! Interestingly enough, that image is of a section of sky 120 degrees wide but only 2 degrees high. Being able to cut through the dust the image shows clear through to the other side of our galaxy–60,000 light years away.

Clicking the above image will bigify what you see. But to REALLY see this in it’s full glory you have to head over to Alien Earths GLIMPSE page. There’s an external viewer there that allows you to peruse the image without actually having to download the whole thing. It’s full of awesome!

You’ll notice this image has lots of color you can see, while in reality infrared is invisible. Well, what good would it do to produce an image in colors that you couldn’t see? These colors have been chosen by the imaging team to represent certain wavelengths. What gets confusing is that the colors don’t always represent the same wavelengths in different images. So if you’re curious you have to reference each specific image. This one, however, is set up this way: Blue represents 3.6-micron light, green shows light of 8 microns and red is 24-micron light. Doesn’t mean a lot to you, huh? Well, just enjoy how pretty it is then.

Here’s what it actually means. Blue specks represent older individual stars while the blueish haze is cast by a surrounding population of older stars. The swaths of green are areas hosting stellar embryos and composed of organic compounds. You’ll find dots of red, orange, and yellow starlets inside. The red haze is mostly gas and dust that have been heated to the point of glowing by nearby stars (much the way we glow to an infrared camera). This dust is very fine and made of pencil-like carbon graphite.

There’s a lot more going on in this image, but you need to see it for yourself. Cruise over to the GLIMPSE site, put on Us And Them by Pink Floyd, and just scroll around for a while. You’ll find yourself feeling much more… human afterwards.

Images Courtesy NASA/JPL-Caltech

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2 responses

13 06 2008
Nick Jones

I’ve got to ask, Did Chevy sponsor the project? If they did, that’s some pretty shameless product placement.

13 06 2008
Nick Jones

In all seriousness though, that’s awesome. I’ve always been fascinated by the telescopes that look outside of the visible spectrum. In fact I educated someone about LIGO the other day and told the story about the master shutdown switch in case an idiot walks into the tunnel. He works with computers so he knew that the chain reaction excuse was lame.

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