Friday, November 24, 2006

Nerd Alert!

Today I totally geeked out when I saw a satellite in the early evening sky. I have seen satellites from time to time, but this time was different. Whereas I have randomly seen satellites before, I was expecting this one.

A few days ago I found a website called Heavens Above that accurately predicts when and where to view satellites. Feed your longitude, latitude, and elevation into the site and it will accurately predict the paths of satellites through the night sky at your location.

Apparently the most visible satellites are the Iridium satellites. While the word Iridium sounds like an element, (and for all I know it might be) in this case it is a company name. Iridium has over eighty of these satellites in orbit and the reason they are so visible is their highly polished surfaces reflect sunlight really well. While we are on Earth, rotating well into the nighttime side of the planet, satellites are still high above us, bathed in sunlight. The intense light reflected by these satellites is called an Iridium flare.

I checked Heavens Above for any Iridium flares that might be visible from my grandparents' house on Thanksgiving, and it turned out one was scheduled for 7:10pm at 49 seconds in the southern sky. It was Iridium 13 and it was supposed to have a magnitude of -7, which is much brighter than any star.

So I wandered around the neighborhood for a good view of the southern sky and looked up at the appointed time. The Iridium flare appeared right on cue and shown down like a spotlight (well compared to the stars anyway). It was truly bright for a few seconds, and then dimmed slowly into nothingness as it continued along its path to the horizon. Pretty neat what you can do with the internet.

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