For more than 50 years, the U.S., the former Soviet Union and many other countries have been launching satellites into space, and many are still up there in various orbits around the Earth.

It all started with the U.S.S.R.'s launch of Sputnik One on Oct. 4, 1957. If you were around back then, you no doubt remember the fervor that created. The bad guys of Communist Russia were in the space age. People wondered what the Soviets would do next: maybe drop nuclear bombs on us from satellite platforms?

It was a real fear. The U.S. at the time was experiencing multiple space failures and catastrophes, but finally managed to launch its first satellite, Explorer One, on Feb. 1, 1958.

Fortunately, nobody dropped A bombs or H bombs into space, but many more satellites were launched in subsequent years. Most of them, then and now, are on domestic and scientific missions, but there also are many military reconnaissance missions, otherwise known as spy satellites.

In the late 1950s President Eisenhower saw the value of spy satellites as a way to keep an eye on enemies and potential enemies to make sure they weren't up to something. They proved to be extremely valuable during the Cuban Missile Crisis in 1962 when U.S. satellites photographed nuclear missile installations being assembled in Cuba.

Since then, satellites have gone a long way in making sure arms treaties are being honored and helping to keep at least some of the peace.

By far, though, there are many more domestic than spy satellites circling our world. Some are in what's called geostationary orbits that allow them to hang over particular parts of Earth. They range in size from the International Space Station to stray nuts and bolts and even tinier bits of blown up fragments. There's a lot of worthless junk up there.

In fact, the U.S. Space Surveillance Network estimates there are more than 12,000 objects in orbit and only about 600 of them are operational satellites. All of the others that manage to stay in orbit are potential hazards to the "good" satellites. The oldest piece of debris still in orbit is the U.S. satellite Vanguard One, a 6Z\x-inch sphere that was launched in 1958 and was in operation until 1964. It is expected to stay in orbit for centuries.

You can actually see many satellites, operating and otherwise, every night in our Butler skies. They look like moving stars traveling against the fixed background. In fact, there's so much traffic up there it's unusual not to see satellites while you're stargazing.

The best time to see the satellites is a few hours after sunset or a few hours before sunrise. That's because the light you see from satellites is reflected sunlight. There's no other way a satellite could be visible to you, even if it had a huge spotlight. Both in the early evening and predawn early morning when the sun is below the horizon from our view, satellites can still catch sunlight because they are so high above the Earth, some hundreds of miles up.

How bright or dim a satellite is depends on its size and reflectivity. Most of them travel across the heavens in general east to west orbits, but some are in polar north-south orbits.

I think the best Web site for keeping up with the visibility of satellites from wherever you're looking from Earth is called Heavens Above and at www.heavens-above.com/.

I mentioned this site a few weeks ago in my stargazing Web site column. It's a wonderful site for not only keeping up with satellites, but also for general stargazing and astronomy.

When you call it up on the Web, you first have to set it for your location. The easiest way to do that is to choose from the immense worldwide database. When you call it up, Heavens Above will ask if you want to register, but you don't have to. It has a whole section on satellites you can have a lot of fun with. It also does a great job of explaining how to use the data for your locale.

One of my favorite satellites also is the biggest and brightest — the International Space Station and the U.S. Space Shuttle.

In fact, they're so bright, you can mistake them for a high-flying aircraft. There's a special section in the Heavens Above Web site that covers just the I.S.S and the space shuttle if it's on a mission. What's really cool is when the shuttle is approaching or departing from the I.S.S. You can see them cross the sky in tandem.

Another really fun thing to see are what's known as Iridium flares. They also have a special section on the Heavens Above Web site.

There are 66 Iridium communication satellites orbiting Earth that are roughly the size of Volkswagen cars, and each have three, large, polished, highly reflective antennas. As these Iridium satellites come over your backyard, and if the angle between you, the sun, and one of these polished antennas is just right, the normally invisible satellite suddenly flares up for a few seconds. These Iridium flares can be really bright, brighter than any star or planet in the sky.

At my star parties, I like to surprise folks with Iridium flares if one is visible that night. I check ahead on the Heavens Above Web site for the time and location and have the unsuspecting star partiers look in that part of the sky at just the right time. It's great hearing all the oohs and ahhs.

Watching satellites is a lot of fun, and all you need to see them are your two eyes. Binoculars and telescopes aren't much good since they move so fast across the sky, and even if you could keep up with them you wouldn't be able to see any details, just a bright light.

Jupiter-Venus put on show this week

Speaking of cluttered skies, make sure you don't miss a great celestial show in the early evening southwest skies this week.

Starting about midway through evening twilight, you can't miss Venus and Jupiter shining closely together in the low southwest. There's nothing anywhere close to their brightness. Venus is the brighter of the two.

Early this week, Venus is just to the lower right of Jupiter, but as the week goes on, Venus will shift to the lower left of Jupiter, and the two planets will huddle up even closer.

By next Sunday, they'll only be two degrees apart and just to the lower right of the dazzling duo will be a thin crescent moon. Make sure you look early in the evening because both planets set together by 7:30 p.m.

Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of the new book, "Pennsylvania Starwatch," available at bookstores and at his Web site www.lynchandthestars.com.