Wozzat?

Tonight marks the last time we'll get a clear view of the Perseids. Of course, with the UK summer being its usual resplendent self, all we've been able to see for the last week is a watery, cloud-filled vault that manages to conceal just about anything really interesting.

So - wot are these 'ere Perseids, then? Well, it's a big load of rocks that thump into our planet every July and August. Best seen in the hours immediately preceding dawn (good news for poachers, then:-) they clobber our little waterworld with frightening speed, about 23000 mph (hope they watch out for speed cameras) and zip across the sky before burning up.

Here's some little known facts about meteors: in an average week, about 200 tons of them hit the Earth and get vaporised. A meteor differs from a meteorite, in that only the latter actually makes landfall. The former disappears in a puff of smoke. And the things that hit the atmosphere are actually meteoroids, which become Meteors when you see them and their light, and meteorites when they land in your back garden.

Final tip: if you've never seen one of these things, don't imagine it to be anything cataclysmic. There's no sound (well, think how far up they are) and all you'll see will be a pencil-thin line of light which suddenly zaps across the firmament - almost instantaneously. Having said that, it's a great experience, and definitely one to show the kids. Just take a sheet on which to lie down and watch; gets mighty painful craning your neck backwards for an hour or so.