The long-term forecast for the Milky Way is cloudy with gaseous rain. A study by Nicolas Lehner and Christopher Howk of the University of

Notre Dame concludes that massive clouds of ionized gas are raining down

from our galaxy's halo and intergalactic space and will continue

to provide fuel for the Milky Way to keep forming stars. Using the Hubble Space Telescope's Cosmic Origins Spectrograph they measured for the first time the distances to huge, fast-moving clouds of ionized gas previously seen covering a large fraction of the sky.

http://hubblesite.org/news_release/news/2011-26