We’ve all been surprised, at some point, on being told by a bald headed man with a face like a map of central London that he’s doing his GCSEs this year and is actually female ‘you cheeky beggar!’, or by a soft skinned man with abundant locks of hair that he’s popping to the Post Office to draw his pension, once he remembers where he left his overcoat. It’s not always easy to guess a person’s age. Well, the same is true with planets. You can’t judge their age by the amount of craters they have, according to scientists.

Mars is younger than it looks.

Mars, for instance, could turn out to be a lot younger than was originally thought, it’s just not aged very well. Too many late nights peering into the night sky wondering what all that colour on earth is about.

Initially scientists believed that craters were the planetary equivalent of wrinkles. Because the assumption was that they were caused by meteorite collisions it followed that the age of the planet could estimated by the amount of them. But now they think that many of them are actually the result of secondary impacts, which is rather like waking up after a particularly heavy night on the beer to find a whole load of wrinkles appearing at once.

The upshot is that scientists now don’t know how old Mars is. And, as it would be rude to ask, they’re going to have to come up with another way of estimating. Blighty suggests checking for the growth of hair in unusual crevices.