That’s a question for a lot of space nerds – and, Apparently, Jeff Bezos’ team at Blue Origin – cares a lot.
There is no single definition of “outer space”. And deciding where space begins is largely an exercise in figuring out exactly where Earth’s atmosphere becomes less of a nuisance than Earth’s gravitational pull. But there is no exact altitude where this occurs. The atmosphere thins, but the “void of space” is never truly devoid of matter. It’s a fuzzy line.
Where does space begin? Does it start when you look up and the sky turns from blue to dark and dotted with stars? What about when you go just high enough to float, as you see with the astronauts on the space station?
Well, space station astronauts aren’t floating because they’re so high, it’s because they’re in orbit. To put it plainly, according to NASA, accentuation ours:
An orbiting spacecraft moves at the correct speed so that the curve of its fall matches the curve of the Earth. Because of this, the spacecraft continues to fall towards the ground but never collides with it. As a result, they fall around the planet. The Moon remains in orbit around the Earth for this same reason. The Moon also falls around the Earth.
And while Branson and his crew won’t go into orbit, they will experience microgravity, as they free fall from the top of their journey, very similar to what astronauts experience on the ISS. Except they don’t move over 17,000 mph like people on the ISS, so the SpaceShipTwo will come back to Earth screaming rather than circling the planet continuously.
But when it comes to suborbital flights – AKA that don’t reach enough speed to enter Earth orbit – the Branson and Bezos space companies are obsessed with the altitude they reach.
Branson’s flight today is expected to reach over 50 miles high, which is the altitude that the US government considers the start of outer space.
Bezos’ flight on July 20 will reach over 62 miles high – also known as the Kármán Line – which is the internationally recognized elevation as a border.
What is correct – the 50 mile mark accepted by the United States or Kármán’s internationally accepted 62 mile line – is widely debated and mostly arbitrary.
But when we say that the international community “recognizes” or “accepts” the 62-mile Kármán Line as a limit in space, we are primarily talking about one organization: the International Aeronautical Federation, which keeps track of world records in spaceflight such as counting the number of people who have become astronauts.
But even the FAI said it was considering changing its definition for the 50-mile mark recognized by the United States in response to research by Jonathan McDowell with the Harvard-Smithsonian Center for Astrophysics.
What you should know: It’s not a big deal. And people who fly Virgin Galactic and Blue Origin – two companies based in the United States – will always be in the recognized American version of outer space. (Although it should be noted, neither company sends passengers into orbit.)
Still, Blue Origin took the opportunity on Friday to turn the definition of outer space debacle into a Twitter argument.