Eli5: How do objects entering the earth atmosphere catch fire? is it from travelling to quick?
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Great explanations so far, but to put things into perspective: the speed required for an object (or satellite or spacecraft) to remain in earth orbit is 18,000 mph. That speed’s obtainable in the near-vacuum of earth orbit, since there’s no air resistance to speak of. When a craft re-enters, it speeds up even more since it has let gravity capture it more effectively.
The world-record re-entry speed IIRC was Apollo 10, returning from the moon, and not just earth orbit – it hit the atmosphere at just shy of 24,000 mph. Those are the kinds of speeds none of us even have a mental benchmark for, it’s tough to intuitively understand just how fast that is. The highest velocity rifle bullets are under 3,000mph, not much compared to re-entry speeds.
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