Back in 1957, the former Soviet Union became the first nation to launch an artificial satellite into orbit around the earth. Since that time, tens of thousands of such objects have been launched into orbit. Along the way, many orbits of these satellites have decayed, and when that happens, they simply burn up as they re-enter the atmosphere. Sometimes, a few fragments will survive and fall back to Earth. Nevertheless, artificial satellites are big business today, and it is estimated that there are over 35,000 such objects that remain in orbit. Can these be seen with the naked eye? Yes, they can, and quite easily.
Obviously, the first requirement is a clear nighttime sky. A heavy cloud cover can prevent one from seeing the moon, stars, and other planets, let alone satellites. The opportunity to see satellites also increases when one chooses to gaze the sky away from cities. An ideal location is thus out in the country, away from city lights, street lamps, and even other traffic if possible. If you happen to find yourself in such a setting, you shouldn’t have to wait any more than about 15 minutes to see a satellite, but you have to know what you’re looking for.
According to Joe Rao, a columnist for Space.com, the best time of night to observe satellites is shortly after sunset or before sunrise, but they can be seen anytime as long as the sky is dark and clear. Most of the satellites that can be seen by the unaided eye are classified as “space junk.” This is essentially a collection of debris from dead satellites or fragments of spacecraft that have broken apart or exploded. Most of this so-called “space junk” ranges from a few inches up to around 30 feet in diameter. Objects smaller than 20 feet in diameter will be too faint to be seen, but there are hundreds that are large enough and low enough (typically 100-400 miles above the earth) that can be seen when the light from the sun is reflected off of them.
Observers may ask the following question:
“How do you know you’re not just looking at aircraft?”
This is very thought-provoking. If you live within 150-200 miles of a major metropolitan area, you will see hundreds of aircraft either ascending from or descending to that airport. Even airliners at peak altitude can easily be seen. But there is one major difference: Satellites will travel across the sky considerably faster. In fact, many can orbit the entire planet in about 90 minutes. Therefore, even if you happened to spot a military jet 50,000 feet up traveling at Mach II, a satellite will cross you field of view over 10 times faster. Aircraft can be seen for longer intervals, not only because that move at a much slower velocity, but also because satellites will pass into the earth’s shadow and seem to disappear.
Here are some more interesting facts:
The very best place to see satellites is from a boat in the Carribean Sea. Satellites used for peaceful purposes travel in an east-west direction while spy satellites follow a north-south route. Many satellites have solar panels and antennae and can thus appear to briefly flare as sunlight is reflected off of them. While satellites move much faster than aircraft, they will still appear to move much slower than meteorites as they make contact with the upper atmosphere, so it’s important not to get these very different objects confused. A useful tip in differentiating meteorites from satellites is that the former closely resembles a pyrotecnic firework while a satellite looks more like a moving star, planet, or distant aircraft.
Of course, the larger the object in orbit is, the easier it can be seen. The International Space Station (ISS) is currently the largest man-made object in orbit today. If an observer is in a favorable location, the ISS can be as bright as the planet Venus. In addition, in isolated moments of sunlight reflecting off the panels, this can increase to 16 times the brightness of Venus! The Hubble Space Telescope can also be seen, provided one knows where to look. If you’d like to see either of these modern-day marvels, there are websites that provide information on exactly when and where to look.
As for smaller satellites and space junk? The Carribean Sea may provide optimum viewing, but any rural, isolated setting and a clear nighttime sky will suffice.