How the edge of space became up for interpretation
As the billionaire space race continues between Richard Branson, Elon Musk and Jeff Bezos, many are asking questions about how far into space they actually went.
Richard Branson’s Virgin Galactic flight on 12 July rocketed up to 86 km off the ground, while Jeff Bezos’s Blue Origin flight recently reached just over 107 km.
However, these figures have experts wondering if either of them truly left the planet’s atmosphere.
Jonti Horner, an astronomer at the University of Southern Queensland, says the age-old questions of where the atmosphere ends and where space begins can be open to interpretation.
“It’s one of those questions that’s a bit like saying, ‘When are you old enough to drink?’ or ‘When are you old enough to drive?’ Every country has their own version of an answer.”
“Where space starts and the atmosphere ends is a little bit like that, in that the atmosphere doesn’t just suddenly stop,” Horner told Cosmos Magazine in a recent interview.
“The higher up you go, the thinner the atmosphere gets, and it keeps getting thinner and thinner and thinner, until eventually you can’t tell that it’s there anymore.”
The official final point is approximately 10,000km above the surface, leaving no surprise why some want the line drawn a little closer to the Earth’s surface.
The US military, the Federal Aviation Administration and NASA all define the edge of space as 80 km off the ground, towards the upper part of the mesosphere.
This definition is very different to The Fédération Aéronautique Internationale (FAI), an international record-keeping body for aeronautics, who have adopted their own definition in the 1960s.
Called the “Kármán line”, it marks the beginning of space at 100 km above Earth’s mean sea level.
Despite all these varying measurements, Horner says they are equally as good and as bad as each other.
“Now that we are in this era of commercial space tourism, suddenly people want to know where [the boundary] is because they want to know that what they did was really good enough.”
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