Monday, October 15, 2018

International Space Station Sightings

For the past four nights, the girls and I have gone outside around dusk to look up and watch for the International Space Station. We've seen it every night.

It's very high up, about 250 miles, so you can't count the cells in its photovoltaic arrays or read the markings on its fuselage or exchange friendly waves with the crew. It looks like a bright star – a lot like Venus – except that it moves fairly rapidly across the sky. In fact, it's moving at 17,500 miles per hour (it orbits the Earth about once every ninety minutes), so if it's visible in the sky above your house for four minutes, then by the time it disappears it has traveled nearly 1,200 miles. Of course, since it's so high up it doesn't look like it's going that fast, only about as fast as an airplane appears to be moving when you see it overhead. (The space station doesn't have visible blinking lights or red lights like an airplane flying in the night sky does, however, so if you think you're seeing the ISS but it's blinking, what you're actually seeing is probably an airplane that's really high up.)

Of course, you can't just go out randomly at night and look up and expect to see the ISS, you need to refer to the following Web site to know when you can see it:

You may have to zoom out on the map to find the location closest to you where "sighting opportunities" are charted, and interpreting the Max Height and Appears / Disappears information is a bit of a challenge; we've found that if you're vigilant about searching the sky around the time when it's supposed to become visible, you can find it within a minute or so.

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