AstroPics

**Viking** · 10-30-2008, 18:27

I've felt like starting this thread for a while; but today I saw a rather...interesting picture. I must admit I knew what it was as I saw it...

indeed, a pair of interacting galaxies.

The Hubble Space Telescope has been having some troubles lately, leading to the planned Hubble service mission (a space shuttle mission) being postponed to 2009. This is the first image returned after Hubble was brought back online.

The blue glow in the galaxy to the right, is the glow from newly formed blue stars. The galaxy collision caused matter to compress and stimulate this star formation. Or, as the Hubble site formulates it:

The blue ring was most probably formed after the galaxy on the left passed through the galaxy on the right. Just as a pebble thrown into a pond creates an outwardly moving circular wave, a propagating density wave was generated at the point of impact and spread outward. As this density wave collided with material in the target galaxy that was moving inward due to the gravitational pull of the two galaxies, shocks and dense gas were produced, stimulating star formation.

The dusty reddish knot at the lower left of the blue ring probably marks the location of the original nucleus of the galaxy that was hit.

An entire gallery of colliding galaxies can be found here.

**Megas Methuselah** · 10-30-2008, 20:47

Very nice! The universe is miraculous. Anyways, I'm glad I don't live in that galaxy.

**Viking** · 10-31-2008, 17:29

Actually, our very own Milky Way Galaxy might be on its course to a collision with the Andromeda Galaxy; though I gather that eventual future generations shouldn't have anything to fear:

The students fear that this may be the end of life, as they know it. But, their teacher reassures her class that there is very little chance of stars from the Andromeda galaxy hitting the Sun or the Earth. Even though the galaxies pass clear through each other, she says, stars in a galaxy are spaced very far apart.

The text does not mention anything about potential new hypernova candidates created due to the compression of the gas that could scorch the Earth a while after the collision have started; but I don't know.

**Ironside** · 11-02-2008, 10:24

If you don't already have this link you're gonna love it Viking (and everyone else that likes astropics for that matter).

Astronomy Picture of the Day