How to Bake a Galaxy: "
Now, a new study from NASA's Spitzer Space Telescope is refining what is known about this essential ingredient of galaxies. It suggests that not only is dark matter necessary, but a minimum quantity of the material must be present before a galaxy can form. Any less would mean no galaxy -- the cosmic equivalent of a failed loaf of bread.

'Galaxies are born within huge clumps of dark matter,' said Dr. Duncan Farrah of Cornell University, Ithaca, N.Y. 'We are finding that these clumps seem to be remarkably consistent in size from galaxy to galaxy.' Farrah is lead author of a paper describing this and other findings in a recent issue of Astrophysical Journal Letters. "