XPost: alt.astronomy, nl.wetenschap   
   From: sorry@noreply.nl   
      
   Op 10-6-2011 3:26, Skybuck Flying schreef:   
   > However I see a little issue with this explanation.   
   >   
   > Let's suppose it was a satellite, let's suppose it was stationary.   
   >   
   > Then this raises the following questions:   
   >   
   > 1. How fast does the earth rotate ?   
   >   
   > 2. How fast does the satellite rotate with it ?   
   >   
   > Would the speed be slow enough to reflect the sun light for about 2 to 3   
   > seconds ?   
   >   
   > Additional explanation could be rotating satellite, which lengthens the   
   > exposure.   
   >   
   > However if calculations would prove that this is impossible then the   
   > hypothesis of a satellite can be dismissed.   
   >   
   > Anybody care to do any calculations ? ;)   
   >   
   > Bye,   
   > Skybuck.   
   >   
   >   
      
   Geostationary satellites move at an altitude of some 36000 km, which   
   makes them very hard to see.   
      
      
   The earth rotates 360 degrees once every 24 hours.   
   The sun takes up about 0.5 degree on the sky.   
   The satellite stays aimed at the sun.   
   The angular velocity of the reflected beam (with respect to the earth)   
   is twice that of the relative rotation of earth and sat.   
   This means that in case of geostationary the max visibility time is   
   (24h x 60 min)/(2 x 360/0.5) = 1 minute.   
   As the phenomenon took only seconds, it must have been a low orbit   
   satellite.   
      
      
   Spotting the movement of a satellite can be rather difficult. Especially   
   when it is only visible for a few seconds. Some satellites take 10-30   
   minutes to cross the sky.   
      
   The lowest satellites have an altitude of some 150 km. They move pretty   
   fast across the sky.   
   The iridium satellites fly at an altitude of 780 km which makes them   
   barely visible slow movers in the sky.   
      
   I have seen hundreds of satellites in the sky, but only one iridium   
   flare so far. That one was pretty spectacular though.   
      
      
   --  Femme   
      
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