Not so many moons ago, I was invited to the Royal Observatory in Greenwich, London, to peer at Mars, or maybe the moon, through a huge and beautiful old telescope. A crowd of us crammed into the room and were awaiting our turn at the eyepiece when a staff astronomer asked if anyone wanted to see the International Space Station. Our faces lit up.

We followed him on to the balcony where he checked his watch, pointed to the horizon across the city and began a second by second countdown. As he reached zero, a bright spot appeared impressively on cue, moved swiftly across the sky and vanished in the gloom. That spot was sunshine reflected from the International Space Station as it hurtled around the planet at 17,500 mph.

For a week beginning tomorrow, far more people will look out for the space station as it loops silently around the world. Thanks to a handful of enthusiasts and the power of Twitter, a global band of like-minded folk have pledged to wave as the station passes overhead. You can keep track of the action, or better still get involved, by following @ISSwave and using the hashtag #ISSwave.

Watching the space station zoom overhead on a cloudless night is an easy and momentary pleasure. The US space agency, Nasa, even runs a website that tells you when the space station will be visible from your area. You might think the space station is a waste of money, that it does little more than give astronauts a place to go. But there is something special about watching that hulk of capsules, trusses and solar panels fly over, knowing men and women are hard at work up there, or tucked up and asleep, or peering back down as continents turn beneath them.

A few months ago, I interviewed a handful of veterans about life aboard the space station. One of them, Piers Sellers, talked about watching the station fly overhead from Nasa's Johnson Space Centre in Houston. Here's how he put it:



You can go out on a quiet night and see the thing flying over and you think, my goodness, I was there, I helped put that together...When we see it here in Houston, we think of them on board, all in their sleeping bags, tumbling around the Earth. Everybody here feels they own a little piece of it. It's a lasting achievement.

The week of waving is a unique celebration of the International Space Station and one that is fitting with this year's 10th anniversary of a continuous human presence aboad the orbiter. Who cares that the astronauts won't see you? So what if you won't see them? It is all about taking part.