How can I spot satellite triads?

By: J. Kelly Beatty July 21, 2006 0

While binocular observing from Northern California on August 19, 2004, at 6:33 Universal Time, I picked up a trio of satellites moving from the northwest to overhead and passing through Cygnus. I’m sure they were satellites, as all three turned reddish at the same time before disappearing into Earth’s shadow. They seemed to be in a near-perfect equilateral triangle, each about 1° from the other. What were they?

Spotting one of these “triads” can be a startling experience, but they’re rather well known among satellite watchers (and UFO buffs). They are Naval Ocean Surveillance System (NOSS) satellite formations. Commonly known by the name White Cloud, these clusters travel around Earth in high, roughly circular polar orbits. The oldest surviving trio was launched in 1986. Usually they are visual magnitude 5 to 7, but under the right conditions they can be readily seen with the naked eye. For more information about them, go to http://satobs.org/noss.html.

— J. Kelly Beatty

About J. Kelly Beatty

J. Kelly Beatty, S&T Senior Editor, joined the staff of Sky Publishing in 1974 and specializes in planetary science and space exploration. Learn more about him here.