Look, Up in the Sky, it’s a Satellite!

If you want to get a tangible grasp of the most advanced technology on Earth, go out in your backyard tonight, after the sun goes down, and look up.  There are stars and planets floating above your head and there are man-made objects too.  It’s hard to believe but there are now human beings living continuously in space aboard the International Space Station (ISS) http://www.nasa.gov/mission_pages/station/main/index.html . The ISS orbits the Earth about every 90 minutes and could be passing over your head right now. You may not have even noticed these satellites passing overhead because you didn’t realize you could see them or didn’t know how to look for them. But you can see some satellites; those in Low Earth Orbit, also called LEO’s. And you have to look at the right time of the night, usually about 45-90 minutes before sunrise or after sunset. This is because in order to see a satellite the sun must reflect off of it and make it visible, since they don’t put out any light themselves.

If you go out and look up at the sky, you may not be able to see any satellites. That’s because unless it’s the ISS or Hubble, most satellites are pretty faint and hard to see. The best viewing is when the sky is clear and there are no clouds and no moon. If it’s at night, look mainly in the western half of the sky. If it’s in the early morning, look mainly in the eastern half of the sky. Use the planets and stars as fixed locations in the sky and scan the sky with your eyes moving from one location to another, across the whole sky, about every second. Humans have good peripheral vision and what we’re attempting to do is use this peripheral vision to detect a satellite’s motion across the sky.  If, while looking at these fixed locations you happen to notice something move in the corner of your eye, look at it and see if it’s a satellite. Satellites usually move from west to east and south to north. How do you know if the object you’re looking at it is a satellite and not a plane? If it doesn’t have flashing or colored lights, it could be a satellite, although some satellites have been known to flash or flare while rotating http://www.satobs.org/iridium.html . If you watched the object move across the western half of the sky at night and it suddenly disappears when it gets in the eastern half, it’s most likely a satellite. This is because the sun will illuminate a satellite for only so long and then it passes into earth’s shadow. With no light reflecting off of it, it is no longer visible and disappears.

So how do you know if you’re looking at the Hubble Space Telescope (HST) or a Russian satellite? For this you‘ll need some information about the orbit of the satellite. The best place to get this information is from the NASA web page at http://science.nasa.gov/realtime/jtrack/3d/JTrack3D.html/ There are also a number of sites that have information about satellite viewing at http://spaceflight.nasa.gov/realdata/sightings/ .Several computer programs are available for tracking satellites and they can come in handy if you have a laptop computer or smartphone at http://spaceweather.com/flybys/ .