The Edge of Space Just Crept 12 Miles Closer to Earth

Where does Earth’s atmosphere end and space begin? According to a new study, it might be just 50 miles above Earth — right about where the blue turns to black in this photo. Credit: NASA
Did you feel that? Does it suddenly feel a little bit stuffier in here to you? Does it feel like, I don’t know… outer space just got 12 miles (20 kilometers) closer?

By Brandon Specktor |

Nothing actually moved, of course (unless you count the constant and increasing expansion of the universe). But according to a new study published online this week, it might be high time Earthlings shifted our mental and mathematical ideas about where, exactly, Earth’s atmosphere ends and outer space begins. [Earth from Above: 101 Stunning Images from Orbit]

If astrophysicist Jonathan McDowell’s calculations are correct, the cosmic boundary where the laws of airspace suddenly give way to the laws of orbital space might be a lot closer than we think — a full 12 miles closer than previous estimates suggest.

„The argument about where the atmosphere ends and space begins predates the launch of the first Sputnik,“ McDowell, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics, wrotein his new paper, which will appear in the October issue of the journal Acta Astronautica. „The most widely accepted boundary is the so-called Karman Line, nowadays usually set to be 100 km (62 miles) altitude.“

Here’s the problem: According to McDowell, that Karman line that many scientists accept today is based on decades of misinterpreted information that doesn’t actually take real orbital data into account. Luckily, data is McDowell’s business (and his pleasure — in his free time he keeps meticulous records of every rocket launch on Earth) and he knew just where to look to find an evidence-based answer to the question, „Where does space begin?“

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