I've just had a cup of coffee in the garden under a very clear night sky, and watched the International Space Station cross over Britain above me.
I've seen this many times and it never fails to amaze me.
You'll see many satellites pass overhead if you spend any time looking at the night sky, most are very faint tiny dots, moving at a steady speed in (of course) a straight line.
The Space Station, when it passes overhead though, is absolutely unmistakeable.
It always passes over Britain from west to east, and is the brightest thing in the sky, more often than not.
Venus (the morning star at present) is very bright indeed in the east, but the ISS competed with even her brightness this morning.
The best time to see the ISS is firstly on a clear night (obviously), and secondly just before the sun comes up, or just after its has set - this will mean sunlight will reflect off the ISS for the longest period of time in the dark, night sky, making it appear very bright for the longest time.
One can quite easily watch the ISS cross the entire sky, from west to east, in the right conditions.
If you are still unsure if what you've just seen in the night sky was a plane (much lower and blinking lights) or any old satellite, instead of the ISS, then click on the new link on the links menu to track the current position of the ISS (direct from NASA), (or HERE).
Like I say though, when you DO see the ISS cross the sky - you'll know you have, you'll not mistake it! It is that bright and that distinctive.
When you do see it, you'll be looking at something about 360km above the surface of the earth, which makes about 16 orbits of the earth every 24 hours, at an approximate speed of 17,000 mph. Just so you know...