We are advised as follows at New Scientist, in “Dark galaxy crashing into the Milky Way” (22 November 2009):
THE Milky Way’s neighbourhood may be teeming with invisible galaxies, one of which appears to be crashing into our own.
In 2008, a cloud of hydrogen with a mass then estimated at about 1 million suns was found to be colliding with our galaxy. Now it appears the object is massive enough to be a galaxy itself.
Called Smith’s cloud, it has managed to avoid disintegrating during its smash-up with our own, much bigger galaxy. What’s more, its trajectory suggests it punched through the disc of our galaxy once before, about 70 million years ago.
I can’t wait till the movie comes out, and I also want to collect the DVD.
More cosmology stories here.