Teflon Coated Satellites Really Shine


Time exposure of an Iridium satellite flare over Duluth — Bob King / News Tribune

I teach a community education astronomy class, and last night we had so much fun looking at the moon and Saturn. The night was windy and warm, and the moon stood high in the south. My favorite moment was when one of the students tried to see Saturn in the telescope. Her first reaction was "I don’t see anything." But when she got her eye in just the right spot, her sudden pleasure at seeing the rings evinced a firecracker of emotion: "Oh-my-GOSH!"

Observing the sky is like chopping wood in that it brings pleasure twice over. First, when you see something yourself, and a second time when you share it with someone.

We’ve talked about seeing the space station and shuttle, but there are a lot more satellites you can find with ease. Some of the most interesting ones are called Iridiums. They’re comprise a "constellation" of approximately 66 telecommunication satellites in orbit some 475 miles high. The name comes from element number 77 (Iridium) on the periodic table. The company who sent them up originally planned to orbit 77 of the units.

The Iridiums are about 12 feet long and three feet wide and equipped with three highly reflective, silver-coated Teflon antennas. When the sun strikes them just right, they produce brilliant flares of light often brighter than Venus. The flares only last 5-15 seconds but they’ll blow you away with their brilliance. Some are even bright enough to see during the day.

Use the table below to find the time and direction to look. The data should work for our region, but if you’re reading this from further away, please go here, log in and select the Iridium satellite link.

Once you get familiar with spotting the Iridiums, take a friend out under the sky and explain that you have a feeling something amazing is about to happen. Then watch their reaction to the flare. I once did this with a class of middle school students on an outing in Ely. For the rest of the evening I had their complete attention.

April 16 9:28:52 (sec.) p.m. Halfway up in sky Look almost due east
April 17 9:22:49 p.m. Halfway up Due east
April 20 9:13:48 p.m. 2/3 the way up in sky Due east
April 21 9:07:46 p.m. 2/3 up Due east
April 22 9:01:42 p.m. 2/3 up Due east

(Closeup of Iridium satellite courtesy of Daniel Deak)

1 Response

  1. Far Side of Fifty

    Hey Bob, I was so looking forward to seeing my first Iridium Flare..but alas..my nap was longer than yours and I didn’t awaken till 9:45. I may have to set a timer or an alarm! Will try agin tonite!!

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