A thin blue arc separating two areas of black.

Image: NASA

World Space Week begins today.

So, where is space? It starts closer than you think. If you could drive straight upwards, you’d be there in less than two hours.

The Karman line, 100 km above sea level, is commonly defined as the boundary between the Earth’s atmosphere and outer space.

But of course the atmosphere doesn’t suddenly cut off, so any definition of where space starts is arbitrary.

Once you’re in space, it goes on for a long, long way. So far, it’s hard to wrap your head around.

This video helps a bit (and doesn’t hurt at all). It’s a remake of the original 1977 “Powers of Ten” video.