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Holiday calendar: Listening for E.T.

The 1,000-foot-wide Arecibo Observatory in Puerto Rico is used for lots of scientific inquiries, such as getting a fix on comets and tracking down radio pulsars. But Arecibo is best-known as the world's biggest listening post for radio signals that might be coming from extraterrestrial civilizations. No confirmed transmissions have been picked up yet, but just in the past week there's been more talk about the prospects for finding extraterrestrial life. Only thing is, that life would probably be more similar to slime mold than little green men. The search for E.T. continues, at Arecibo as well as the Allen Telescope Array in Northern California.

This half-meter-resolution picture of Arecibo's giant radio dish was taken by the GeoEye-1 satellite last year, from an altitude of more than 400 miles. If you look closely at the full-resolution version of the image, you can easily make out the cars in the observatory's parking lot, and even the 40-foot swimming pool. I had a ground-level tour of the facility seven years ago and wrote up this little travelogue about it.

Today's view of Earth's E.T. ear serves as the holiday treat behind Door No. 7 in our Cosmic Log Space Advent Calendar. Every day until Christmas, you can look forward to another image of Earth as seen from space. Here are the previous pictures in the set, as well as links to three other Advent calendars with space themes:


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