Expert: Philip Stahl - 2/24/2009

Question
Can you confuse stars and man made satellites? I thought you can see the lights on man made satellites from the earth and they can look like stars.  My boyfriend says the satellites are so far away that it is physically impossible to see them from the earth with no telescope and just the naked eye.  Who is right?

Answer
Hello,

Having observed many satellites in my younger days (e.g. Echo I) I can tell you that it is straightforward to distinguish them from stars because they MOVE - beyond and more rapidly than what the Earth's own rotation can account for. Thus, if one watches long enough (preferably with good 7 x 35 mm binoculars) one can always tell a satellite from a star. (Admittedly, higher altitude satellites will take longer to see move against the firmament, but they are still obviously undergoing motion independent of stars)

Most satellites are not that "far away", operating at altitudes of 250 miles or less. Thus, they CAN be seen IF one knows where to look, and preferably has a good pair of binoculars handy.

In one sense your bf is correct, since few satellites today are as bright as the Echo I was (I believe it was about magnitude -1, or close to it. In other words almost as bright as Sirius). But Echo had an enormous surface area and reflected lots of sunlight.

Thus, there aren't as many satellites today that can be seen with the naked eye. However, provided you view from a relatively *dark* area (NO lights or very few!) , you *can* see them.

This link may provide more help and suggestions in doing so, it also goes into more details on the criteria governing their visibility:

http://www.satellite-orbits.info/articles/satellites/other-visible-satellites.ph...