Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2002 July 28 
Posted on 07/28/2002 1:00:24 AM PDT by petuniasevan
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2002 July 28
Explanation: No one knows for sure what caused this signal. There is a slight possibility that it just might originate from an extraterrestrial intelligence. The bright colors on the blue background indicate that an anomalous signal was received here on Earth by a radio telescope involved in a Search for Extraterrestrial Intelligence (SETI). A search for these signals is ongoing by several groups including volunteer members of the SETI League. Time labels the vertical axis of the above plot, and frequency marks the horizontal axis. Although this strong signal was never positively identified, astronomers have identified in it many attributes characteristic of a more mundane terrestrial orgin. In this case, a leading possibility is that the signal originates from an unusual modulation between a GPS satellite and an unidentified Earth-based source. Many unusual signals from space remain unidentified. No signal has yet been strong enough or run long enough to be unambiguously identified as originating from an extraterrestrial intelligence.
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