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earthman2110
2004-Mar-01, 12:28 AM
where is the center of the milky way in relation to the rest of the sky? and why does it not look much different than the rest of the milky way? does it even have a center? maybe it does look different than the rest, maybe i just dont know where to look. thanks

Ut
2004-Mar-01, 12:44 AM
If you're in a location where you can see the Milky Way clearly, then you can see (during the right seasons, anyway) an area where it seems to get very dusty. The band becomes rather irregular, due to the fact that there is a lot of dust between us and the rest of the stars in this region. The centre is in that area.

You can see an example here (http://www.mreclipse.com/Astrophoto/SS97galleryC.html). The centre is the orange area in the first picture on that page. You can't really see that with the naked eye, as it requires a timed exposure.

Andromeda321
2004-Mar-01, 12:45 AM
The center of the Milky Way lies in the constellation Sagittarius. You can't see the center because there are clouds of dust obscuring it. Dust clouds also obscure much of the rest of the Milky Way.
If the clouds weren't in the way, however, you'd see a point of light brighter then Venus. If there were no dust clouds at all the Milky Way's glow would be bright as day.

AGN Fuel
2004-Mar-01, 01:08 AM
where is the center of the milky way in relation to the rest of the sky? and why does it not look much different than the rest of the milky way? does it even have a center? maybe it does look different than the rest, maybe i just dont know where to look. thanks

As noted by Andromeda321, the centre of the Milky Way galaxy is in a line of sight through the constellation of Sagittarius.

The extinction of light due to interstellar dust & gas was one of the reasons why for many years it was thought that our solar system was near the centre of the galaxy: IIRC, it was William Herschel that tried to establish the relative distributions of stars around the Earth in the plane of the Milky Way. He found it relatively consistent in all directions, which led him to assume that the Earth must be toward the centre of the galaxy. Unfortunately for his hypothesis, the galaxy was much bigger than he had assumed and the light from the more distant stars had been fully extinguished by the intervening dust (especially in the direction toward the galactic centre).

One way to think about his problem is being put down at random into a large forest - you can only see a certain distance in all directions before your view is blocked by a tree, so it is impossible to see the clearing beyond the forest. If you believed the forest was very small, such a view might lead you to assume that you must be close to the middle of it.

Eroica
2004-Mar-01, 12:18 PM
One way to think about his problem is being put down at random into a large forest - you can only see a certain distance in all directions before your view is blocked by a tree, so it is impossible to see the clearing beyond the forest. If you believed the forest was very small, such a view might lead you to assume that you must be close to the middle of it.
Everyone lives at the centre of his own neighbourhood. 8)

Hamlet
2004-Mar-01, 03:51 PM
Here's (http://cassfos02.ucsd.edu/public/tutorial/MW.html) a nice link that may help.

We can get some idea of the center by taking images in the infrared band. The dust obscuring visible light is less opaque to infrared. Here (http://www.ipac.caltech.edu/Outreach/Edu/ourgal.html) are some nice images.

Demigrog
2004-Mar-01, 04:30 PM
Interesting topic. We have telescopes observing objects 13 billion light-years away; if dust clounds are so significant, I assume these objects are in directions away from the center of our own galaxy?

I'm curious as to what percentage of the sky is obscured in this way, and whether that incomplete data might be biasing theories on the mass and age of the universe. (I assume people who do this for a living would account for it, but I'm still curious).

Hamlet
2004-Mar-01, 05:27 PM
Interesting topic. We have telescopes observing objects 13 billion light-years away; if dust clounds are so significant, I assume these objects are in directions away from the center of our own galaxy?

Yes. Any object that would be in a direct line of sight between Earth and the center of the galaxy would be obscured in visible light.



I'm curious as to what percentage of the sky is obscured in this way, and whether that incomplete data might be biasing theories on the mass and age of the universe. (I assume people who do this for a living would account for it, but I'm still curious).

The bulk of this dust shows up in galaxies, but there is some gas and dust in the voids between galaxies. This is taken into account by astronomers, but I don't have a handy reference right now.

TheGalaxyTrio
2004-Mar-01, 06:18 PM
We can't see the forest for all the trees.

Replace forest with galaxy and trees with dust lanes.

daver
2004-Mar-01, 06:41 PM
Everyone lives at the centre of his own neighbourhood. 8)
I didn't--we had a creek on one side that effectively blocked exploration in that direction. So I lived on the edge (actually the corner--there wasn't much interesting upstream) of my neighborhood.