Using Distant Quasars to Illuminate Interstellar Medium

Astronomers at The University of Illinois have recently gathered evidence  for swirling clouds of gas surrounding other galaxies that are much more dynamic than predicted. It was previously thought any significant change in these gas clouds would take longer than a human lifetime and therefore would not be noticeable. Spectroscopic analysis of the absorption spectrum of gas clouds analyzed by astronomers provide evidence otherwise. These astronomers are using distant quasars to illuminate gas that is between the quasar and earth; the quasars illuminate the gas and the gas clouds absorb the light in a specific way depending on its composition. By analyzing the same quasars (and gas clouds) more than once over a period of about 5 years, the astronomers were able to show that the clouds are changing. One possible explanation is that the gas clouds are small, much smaller than theory predicts. Here is a link to the article  http://www.sciencedaily.com/releases/2014/01/140108154517.htm .