The International Space Station (ISS) is a habitable satellite that was launched on October 31 2000 and has had continued human occupation ever since, the longest on record. It's an observatory and research laboratory in low Earth orbit with crew conducting experiments in Biology, Physics and Astronomy, amongst other things. The station orbits the Earth every 90 minutes, and in 2010 it had racked up almost 60,000 orbits, accruing a whopping 1.5 billion miles. To give you an idea of its size, in total it's about the area of a U.S. football field, and weighs over 400,000 kilograms. You can see the ISS without a telescope; the best time is the few hours after sunset or before sunrise.
If you want to take a look at what it's doing and have a sneaky peek at the crew whilst they're on duty, check out the live ISS stream here!
If the stream displays a black/blue screen, there has been a temporary loss of signal. Check back later.