• Question: when does the sky become space?

    Asked by 758spdm24 to Lisa, Mark, Rachel, Sammie, Stephen, Tim on 12 Mar 2018.
    • Photo: Tim Duckenfield

      Tim Duckenfield answered on 12 Mar 2018:


      Short answer: about 100 kilometers (62 miles).
      Long answer: Well it actually depends a little bit how you look at it, and a bit on what the weather is like. To help different countries work together, scientists all agree to use a boundary we call the “Kármán line” which is about 100 km (62 miles) up. This is the height at which you have to go a specific speed called “orbital velocity” to stay this high – this is the speed rockets have to be faster than in order to escape Earths gravity. This speed depends on the weather a bit. Also if you define space to be a certain vacuum, for example, the height would be different. We just use the Kármán line to make space missions easier to organise!

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