ISS : International Space StationThe International Space Station (ISS) is so large — about the size of a football field — that that you can see it from Earth with an unaided eye if you have a clear sky and you know where and when to look.

Unlike an airplane, the ISS has no lighting of its own. Just like planets or the Moon, the space station reflects sunlight off its surface. The best viewing time is generally just after sunset or just before sunrise.

I’ve always been interested in space travel and have enjoyed watching the ISS go overhead. NASA’s web site will tell you where to look in the sky based on your viewing location on Earth. But I’ve found an even better tool: the Satellite Visibility iPhone app from Psychic Psquirrel Psoftware.

When there’s a clear sky late in the day I inevitably wonder if it will be a good evening to spot the space station. A quick check of the Satellite Visibility app tells me what’s orbiting overhead now, how bright the objects will appear and where and when to look. Sometimes the ISS isn’t scheduled to pass by — and sometimes it is. But it’s always worth checking!

Satellite Visibility iPhone AppThe operation is simple. It uses the iPhone GPS coordinates to determine where you’re located. Then it figures out all the potentially visible satellites or space objects that are orbiting overhead. (The space station will be the brightest object.)

If the ISS is scheduled to make a pass overhead, I’ll go outside a few minutes before it’s supposed to appear and use the iPhone’s compass to orient me to the proper direction. The space station looks like a fast moving bright star going across the sky. It will show up and then quickly fade out on schedule — just as the Satellite Visibility app predicts.

I’ve tried binoculars, but they didn’t really help. As a matter of fact, I didn’t see any more detail, and it made it more difficult to track the moving object. The naked eye seems best for me.

I find it truly amazing to think that there are (currently) six people inside the ISS, flying 215 miles above the earth, traveling at over 17,000 mph, completing 16 trips around the earth every day.

Additional Info: Photographing the International Space Station