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How to Spot a Satellite

Week of August 10, 1998
By some counts, there are as many as 8000 objects bigger than about 10 or so centimeters in low Earth orbit. Some of these objects are pretty small, but others are quite large, such as the Russian space station Mir. Most people not familiar with the night sky are surprised to find out that many of these satellites are easily visible to the naked eye on any clear night. Usually they appear as a faint star, moving slowly across the sky. Sometimes they start faint and get brighter (as they get nearer they get brighter), sometimes the brightness oscillates (if the satellite tumbles in orbit), and sometimes you can get a very bright flash off of a reflective surface on the satellite.

Just after dark you can usually see as many as three or four satellites in an hour. Until recently, though, predicting just when and where to look has been the field of people working for NORAD (U.S. and Canadian defense) or people with sophisticated software for their computers.

But that has all changed. In Germany, a man named Chris Peate has done all this work for you. At his Heavens Above Satellite Visibility Page he invites you to either choose your location from an extensive (and worldwide) list of cities, or enter your latitude and longitude. When you are finished, you will be sent to a page that gives you options on what kind of satellites to look for: very bright ones, faint ones, just the Mir, etc. After you choose, it will list times and locations of the satellites for that day.

My astronomy friends and I check his web site every day now to find out what we might catch that night. I saw Mir twice last month in one weekend, and in one of the passes it flared hugely bright, getting much brighter than even an airplane or the planet Venus. Spectacular! His web site is an amazing piece of work, and I highly recommend it to anyone planning on stargazing.

©2008 Phil Plait. All Rights Reserved.

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