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The Question

(Submitted February 14, 1998)

I heard on the news tonight that a dark matter galaxy recently collided with the milky way. And that astronomers aren't worried because it has previously happened ten times. I can't find any more information about this anywhere on the Web. My astronomy knowledge is somewhat limited. I am not a student, I am a screenwriter.

The Answer

The announcement of a small galaxy colliding with ours was made by astronomer Rosemary Wyse at the annual meeting of the American Association for the Advancement of Science in Philadelphia in February.

The dwarf galaxy is not a "dark matter" galaxy, but rather the dark matter mixed in with the rest of the material in the dwarf galaxy appears to be holding it together under the gravitational tidal forces exerted by our galaxy. The proximity of this dwarf galaxy, however, will allow astronomers to better study the nature of dark matter.

Try for a description of the Saggitarius Dwarf in more details.

Jim Lochner
for Ask an Astrophysicist

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