During the lulls between Perseid meteors flashing overhead this past week, my family and I spent time tracking satellites. Unlike meteors, satellites swarm like bugs in the sky regardless of the date. These spacecraft are visible for a few hours after sunset and before sunrise. At these times, sunlight is still shining above us on the upper regions of Earth’s atmosphere, reflecting off the artificial satellites and making them visible.
Easy to spot once you know what to look for, satellites look like dim stars sailing quietly across the sky. Satellites appear to move at about the pace of a jet or a bit slower, but their steady, unblinking light easily separates them from airplanes. Although they can move in any direction, the majority of satellites are in a polar orbit, which means they move from north to south or south to north.
Satellite-gazing is an enjoyable activity that requires no special equipment.
Satellite-monitoring systems track these artificial objects overhead, and websites such as Heavens-Above.com relate the details of each satellite. Enter your location to find out what that satellite was that you just saw, or get predictions of where and when to look to see specific spacecraft such as communications satellites, spent rockets, the Hubble Space Telescope, and the International Space Station, among others.
One constellation of communication satellites can create brief flashes of light so bright that they outshine all other stars and planets and can be visible in daylight. Known as Iridium flares, they are easily distinguished from meteors because their rise to peak brightness and subsequent dimming is much slower than a streaking particle of dust burning up in our atmosphere.
Learn more about satellite observing before your next night of stargazing.
Photo credit: NASA
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Kelly Kizer Whitt loves clean, clear, and dark skies. Kelly studied English and Astronomy at the University of Wisconsin-Madison and worked for Astronomy magazine. She is currently the Feature Writer for Astronomy and Space at Suite101.com. You can follow her on Twitter at twitter.com/Astronomommy.