Archive for the 'Pretty Pictures' category

Friday Galaxy : the Milky Way to outside observers (NGC 6744)

Mar 16 2007 Published by under Pretty Pictures

This is an image of NGC 6744, taken with the South African Large Telescope.

ngc6744_salt.jpg

NGC 6744 is a classic spiral galaxy, and appears similar to how the Milky Way would look if we were able to get outside of the Milky Way and look back at it. Notice that there is a bar at the center of the galaxy (oriented vertically in this picture). That is a feature that you see in a lot of spiral galaxies, and which indeed is present in our own spiral galaxy.

This image isn't exactly how the Milky Way would appear to our eyes. First of all, the surface brightness of the galaxy is low enough that our eyes wouldn't see any color, even if we were very well dark-adapted. However, suppose that our eyes could integrate; even then, this is a somewhat "false color" image. Images taken in near-ultraviolet, blue, and near-infrared light have been mapped to the blue, green, and red channels of the displayed image. As such, color contrasts have been somewhat enhanced.

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"Friday" Galaxy Blogging : The Milky Way (to our eyes)

Mar 10 2007 Published by under Pretty Pictures

It's called "The Milky Way" because if you don't know what you're looking at, it looks like a hazy, nebulous path across the sky.

But try this : go down to Chile, or somewhere else in the Southern Hemisphere. Go outside at a nice, dark site, and stay out there so your eyes adapt. If the galaxy is passing overhead, you will see something like this:

galaxy.png

This is a picture taken by an all-sky cloud monitor camera at the Cerro-Tololo Inter-American Observatory. Around the edge of the picture is the horizon; you can see the silhouettes of the telescope domes. And, directly overhead, is the big and impressive edge-on spiral galaxy that we are inside. The "Milky Way," with a telescope, resolves to lots and lots and lots of stars. You can see the bulge near the center. The contours are irregular, because the disk of the galaxy is filled with dust clouds, some of whicih are closer to us, some of which are farther from us. All of the stars in this picture are in the Milky Way; they're just the closest ones, that look spread out on the sky to us because we're embedded in the disk.

It's a very impressive sight. I strongly recommend that everybody in the Northern Hemisphere find a way, sometime in their life, to get down to the Southern Hemisphere sometime in the fall when they can see this. And if you're already in the Southern Hemisphere, and haven't seen this-- get to it!

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Friday Galaxy Blogging : IC 342

Mar 02 2007 Published by under Pretty Pictures

This is face-on spiral galaxy IC 342, taken with the Mosaic-1 Camera on the 4m Kitt Peak telescope by Travis Rector and Heidi Schweiker. (Image credit: T.A. Rector/University of Alaska Anchorage, H. Schweiker/WIYN, and NOAO/AURA/NSF).

ic342-500.jpg

It was released by NOAO a week ago at a symposium in Washington, DC on light pollution. Here is the NOAO press release.

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Friday Galaxy Blogging : NGC 1365

Feb 23 2007 Published by under Pretty Pictures

In the tradition of "Friday Cat Blogging" (in which I will doubtlessly indulge at some point, what with being a nutty cat person), I intend to establish my own tradition of putting up some pretty picture or another of a galaxy each Friday. Today is barred spiral galaxy NGC 1365.

ngc1365sm.jpg

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