Famously, in Star Trek, space is the final frontier. But where is the frontier of space, or in other words: Where does space end, and the Earth’s atmosphere begin? I was prompted to think about that when I read an amusing sarcastic piece about Justin Bieber apparently going into space, aboard what Richard Branson’s Virgin Galactic calls a spaceship. I don’t think I have ever knowingly heard any Bieber song. I am comfortable with this. As I understand it, the students I teach, who are half my age, are too old for Justin Bieber. This makes me a long way from his target demographic.

But still, for the record, it would be good to know if indeed he and his fellow Virgin Galactic ‘astronauts’ are in fact going into ‘space’. Apparently they are going about 60 miles, or 100 km, up. The mighty Wikipedia makes that around the top of the Earth’s mesophere, the part of the atmosphere above the stratosphere. This is pretty high up, but it is only just above the altitude of the highest clouds, albeit rather wispy ones – see the stunning picture of them up top. Incidentally that was taken from space, from the ISS which is 370 km above the Earth’s surface. So there is air and indeed ice up there, although very thin and cold air.

I also wondered whether any satellites were this low, but apparently due to drag slowing them down (and so causing reentry) satellites are almost always 300 km up at least. Three times higher than the ‘astronauts’.

So he is only a third of the way to the lowest orbiting satellites and there is still enough air and water to form clouds. I would not call that space. I don’t think the Alien tagline applies here, I think we could still hear him scream.