Saturday, September 6, 2008

Huntin’ Satellites

"What the heck was that?" my uncle cried.

We were all reclining around the campfire in the semi-nirvanic state that roaring outodoor fires seem to put people in. Some of us had beers, some didn’t, some were chatting, others were silently making their way through the myriad of stars shining down from the crisp and clear night.

Uncle was one of those others.

What did he see?

A faint yellowish object, similar to a star, except that it moved. Not a quick flashy jump like a meteor. No, this was a deliberate, straight trek across 25 or 50 degrees of sky. Then, it simply vanished.

No one believed him at first. Then he spotted another.

That piqued everyone’s interest. Soon, several more were spotted. My brother became quite adept at predicting where one would pop up. The shiny objects all appeared in the same general area of the sky but in difference places, all doing that slow orbit for a couple of fists-at-arm’s-length across the celestial backdrop, then fading out.

It was determined, after some debate, that we were sighting satellites.


After half-a-century in the business of heaving junk past escape velocity, mankind has succeeded in placing about 10,000 satellites in orbit. Some are planned and purposeful, such as communications, weather, and spy satellites, some less so, such as discarded rocket stages and the occasional lost wrench. Apparently, now, hundreds of these satellites are visible to the naked eye.

Since they’re visible only because they reflect sunlight, satellites are only spotted, say, between 45 and 90 minutes before sunrise or after sunset. After that, the earth’s shadow prevents sunlight from reaching them. They range in altitude from about 100 miles upwards to 25,000 miles. Though the size of individual satellites vary greatly, most of the ones you can spot are about the size of a small bus or a large SUV.

There’s three broad types of orbits these satellites can assume. First, there’s the geostationary orbit, which plants the satellite above the same spot of Earth because it’s period of revolution is the same as our planet’s. These are generally too far to see without the aid of a telescope. The other two types of orbits are polar, ’cause they orbit north-south and go over both poles, and equatorial, which are perpendicular to polar orbits. The lower the orbit, the faster it’s revolution. Satellites in Low Earth Orbit, about 185 miles up or so, take about 90 minutes to orbit, so you might catch ’em twice in one viewing. And if you see what appears to be a blinking satellite, it’s likely to be that discarded rocket stage tumbling along in orbit.

There’s a whole group of communication satellites called Iridium that are parked in orbit 492 miles up that offer excellent viewing. Silver-coated Teflon antenna arrays mimic mirrors, brightly reflecting sunlight down to the darkened Earth below.

The space shuttle and the International Space Station are the brightest man-made objects you’ll see up in the skies. I don’t think we ever spotted them, though. I kinda think we’d know it, you know?

If you’re curious enough to try to spot a few, the website www.satobs.org is a good place to start before you head outdoors. And www.heavens-above.com offers a when-and-where guide to help you find the best, biggest, and brightest satellites.

My uncle may have started it, spotting our first satellite oh-so-many years ago – now it’s your turn to finish it!

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