Intergalactic Tidal Debris

Today’s Astronomy Picture of the Day features a pair of celestial objects, the beautiful Whirlpool Galaxy and its rump companion NGC 5195. Whirlpool is something of a man galaxy-eater. One of its spiral arms seems to be stabbing its companion. Note the haze-like streams, especially around NGC 5195. Those are thousands of stars stripped away by the interaction of gravity between two colliding forms.

The Mice Galaxies (Image credit: ACS Science & Engineering Team, NASA) have had a harder time of it:

Not only have stars been scattered, but note the “mouse” on the right. Those brighter blue star-forming regions have also been smeared across intergalactic space. They’ll produce another generation of new stars, but those nurseries will eventually fade and die over the next several million years.

What if Earth and its sun were in one of these streams? Instead of the Milky Way spread across the night skies away from cities, we might see a patch on just one side of the sky. Instead of two thousand stars to wish upon, there might be several dozen. Probably nothing as bright as the planets. Perhaps not evenly distributed as we see it from our perspective within a galaxy. That would change our mythology and our expression of it.

It is thought that our galaxy is on a collision course with the Andromeda Galaxy. If so, it’s still a very long way off into the future.


About catholicsensibility

Todd lives in the Pacific Northwest, serving a Catholic parish as a lay minister.
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