What happens when galaxies collide? – Space Discovery Documentary

What happens when galaxies collide?  - Space Discovery Documentary Listen

A livestream from Space Documentary published in Space

Two galaxies are drawn together by forces they can't see but they can feel. It's a mutual gravitational attraction. It's inevitable: Inch by inch, light-year by light-year, as the cosmic clock ticks on through the eons, the galaxies grow closer.

They can't help it; their motion was set by tiny instabilities billions of years ago that have only grown stronger in the eons since. As they near each other, the galaxies begin to embrace as thin tendrils of gas and stars reaching out through the tenuous medium between them.

Then, they collide. These two massive structures, each 100,000 light-years across, host hundreds of billions of stars. During the merger, 100 trillion suns' worth of material collide, mix and ignite. [When Galaxies Collide: Photos of Great Galactic Crashes]

And what's left after the fireworks? A broken, dim, dying galaxy — one that will never shine as brightly or as fully as it could in the era before the great disaster.

It's a tragic dance, a story told over hundreds of millions of years. And it's one that we only recently began to understand.