Roughly twice a month, ham radio hobbyist Mike Coletta’s homemade antenna picks up a steady tone that grows louder and then softer before disappearing for another two weeks. It’s the sound of the moon reflecting radio waves that originated on Earth. Coletta tracks all kind of near-Earth objects: the International Space Station, satellites, meteors. Signals picked up by the antenna, which is made of a 10-foot wooden board and metal coat hangers, are converted into tones that differ depending on the direction and location of an object. The tones, layered over a background of heavy static, grown louder and then softer as the object passes by, like a train traveling toward you and then barreling away. Read great article at Gigaom.com.