How to Spot Satellites

From: LiveScience.com, 19 June 2009

By Joe Rao, Space.com Skywatching Columnist"

“If you go out…near dusk or dawn, and you have relatively dark skies, …(within)15 minutes…you see one of the more than 35,000 satellites now in orbit around Earth.

“…most satellites -- especially the bits of debris -- are too faint to be seen with the unaided eye. But…several hundred can be spotted with the unaided eye. These are the satellites that are large enough (typically more than 20 feet in length) and low enough (100 to 400 miles above Earth) to be most readily seen as sunlight reflects off them.

“The International Space Station (ISS) is by far the biggest and brightest of all the man-made objects orbiting the Earth. On favorable passes, it can appear as bright as the planet Venus, at magnitude -4.5

“Along with the ISS, you can also look for a space shuttle on those missions when one is approaching or departing from the space station. Also visible to the naked eye is the newly refurbished Hubble Space Telescope.

“And with good binoculars, you might also try sighting the infamous "ISS Toolbag" which accidentally was allowed to drift into space…Nov. 18

“From now through the final days of July…nights are now the shortest and the time that a satellite in a low-Earth-orbit (like the ISS) can remain illuminated by the Sun can extend throughout the night, a situation that can never be attained during other times of the year. Because the ISS circles the Earth about every 90 minutes on average, this means that it's possible to see it not just on one singular pass, but for several consecutive passes.

“So what is the viewing schedule for your particular hometown? You can easily find out by visiting one of these four popular web sites:”

• Chris Peat's Heavens Above
• Science@NASA's J-Pass
• NASA's SkyWatch
• Spaceweather.com

“Each will ask for your zip code or city, and respond with a list of suggested spotting times.”