By Ron Cowen
A radio telescope has detected hundreds of hydrogen clouds in the gaseous halo that surrounds the disk of our galaxy. This previously unknown population may have been lofted into the halo by a galactic fountain–powerful winds from supernova explosions within the disk.
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Astronomer Felix J. Lockman of the National Radio Astronomy Observatory in Green Bank, W. Va., discovered the clouds while searching the halo for 21-centimeter radio-wave emissions–a signature of atomic hydrogen. Using the Robert C. Byrd Green Bank Telescope, Lockman found the clouds and examined 38 of them in detail. They have an average diameter of 100 light-years and weigh between 50 to 100 times as much as the sun.