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Hubble Photographs Dozens of Colliding Galaxies

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By Andrea Thompson
Staff Writer
posted: 24 April 2008
09:00 am ET

A huge set of new Hubble Space Images show galactic collisions in action and the variety of peculiar forms that merging galaxies can take.

The series of 59 new photographs, released today on the 18^th anniversary of the Hubble Space Telescope's launch, are the largest collection of Hubble images ever released together.

Galaxy mergers are now known to be more common than was previously thought. They were even more common in the early universe than they are today. The early universe was smaller, so galaxies were closer together and therefore more prone to smash-ups. Even apparently isolated galaxies can show signs of past mergers in their internal structure.

Our own Milky Way contains the debris of the many smaller galaxies it has brushed against and devoured in the past. And it hasn't stopped munching away at its neighbors: It is currently absorbing the Sagittarius dwarf elliptical galaxy.

The Milky Way isn't the top predator though, as our giant neighbor, the Andromeda galaxy, is expected to devour the Milky Way in about two billion years. The future resulting elliptical galaxy has already been dubbed "Milkomeda."

Arp 148, nicknamed Mayall's object, is the aftermath of an encounter between two galaxies, resulting in a ring-shaped galaxy and a long-tailed companion. The collision between the two parent galaxies produced a shockwave effect that first drew matter into the center and then caused it to propagate outwards in a ring. Arp 148 is located in the constellation of Ursa Major, the Great Bear, approximately 500 million light-years away.