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Hank acknowledges the amazing feat performed by Felix Baumgartner and answers many of your questions about why it is so amazing.

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Austrian thrill seeker Felix Baumgartner just took and somehow survived his leap from the edge of space, during which he broke five different world records, as well as the freaking sound barrier. This raises quite a number of science-y questions, that I would like to answer for you.

(Intro music plays)

 Is this actually the edge of space?

Question number one: Is this actually the edge of space? No! It's not. It's not even close. The politically defined border of space is 100 kilometers up, and Baumgartner jumped from 37 kilometers - not even half-way there.

Even the 100 kilometer border between atmosphere and space is both arbitrary and incorrect, that border was created purely for political reasons as part of international treaties for preventing the militarization of space.

Scientifically, there are still remnants of the Earth's atmosphere as far as 10,000 kilometers away, so you could, technically, say that the International Space Station is actually in the upper atmosphere, though we generally don't because International Upper Atmosphere Station sounds way less cool.

 Why don't all skydivers break the sound barrier?

Why don't all skydivers break the sound barrier? It is true that all skydivers reach terminal velocity, so if the velocity is terminal, why is Felix faster?

Well, because terminal velocity is determined, literally, by the number of air molecules that you run into as you fall, and at 37 kilometers up, there's 99% fewer to run into. Thus, Baumgartner's terminal velocity at the beginning of his jump's way faster than normal - faster than the speed of sound, in fact.

After the first forty seconds or so, the thickening atmosphere slowed him to more normal, but still freaking terrifying speeds.

 Why doesn't he go higher than that?

 Why doesn't he go higher than that? Well, a couple of reasons. First, because Baumgartner jumped from a helium balloon, and helium rises because it is less dense than air, but as you go higher, the atmosphere gets less and less dense.

You better believe that Baumgartner would have jumped higher if he could, but 37 kilometers is about as high as you can get without putting him on a rocket.

Another reason, though is that the higher Baumgartner goes, the more dangerous it is. If he went, say, two times higher, there would be even less friction, and his terminal velocity would be exponentially higher. Hitting the troposphere, or the thicker part of like the lower atmosphere at speeds like that could be deadly.

 Why doesn't he just float away?

If he's in space, why doesn't he just float away? Gravity keeps doing its gravity thing a really long way away from the earth. That's why the moon, some 380,000 kilometers away, is still stuck in the Earth's gravity well.

The reason astronauts experience weightlessness isn't because they're outside of the Earth's gravity well, it's because they're in orbit. 

For more information on that, it's a little bit confusing, so I'm not going to try to explain it to you really fast, you can check out this video that my friend Derek did. It's really good.

So, there's plenty of gravity acting on Baumgartner. Only very, very slightly less than is acting on you and me right now. 

 Why is he so crazy?

Is there a scientific explanation for someone being crazy? I don't know. That seems like a topic for maybe its own episode. Like, what is thrill seeking, and why do we do it? Actually, that sounds kind of like a good idea. We'll try to write something up on that. And if you want to know about it, you should go to and subscribe.


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