字幕表 動画を再生する 英語字幕をプリント So, I live in Montana and it's winter right now and it's cold and in February walk outside and looks like this. And sometimes I just wish that i lived on Mercury, yeah that looks nice. So, the Sun is awesome whatever you're doing right now you're only able to do because of the Sun. Because the Sun gives us its heat, and its light which makes photosynthesis happen, which makes all of the food that you eat. You might as well know how it works. The Sun is really nothing more than a giant massive nuclear explosion that just keeps on exploding, and exploding, exploding, exploding. So, the Sun was formed about 4.5 billion years ago the same way that all other stars form: there was a bunch of gas in the Universe and some of the gas started clumping together because of gravity, the more that that gas clumped together the more gas wanted to be there and come together so hard that eventually two atoms of hydrogen fused together into helium producing huge amount of energy and that started off a chain reaction that became the power of our Sun. So, now at its core – where all the, you know, real interesting action happens – the temperature there is about 27 million degrees Fahrenheit. From there it takes about a hundred and seventy thousand years for that energy to reach the surface of the Sun. By that time it's cold to a balmy 10,000 degrees. Often you'll hear people say: "They're going to make this as hot as the surface of the Sun", and it's important to note the surface of the Sun not that hot compared to 27 million degrees. Other examples of hydrogen fusion that you're probably familiar with the do not occur on the Sun include the Tsar Bomba: the most powerful nuclear weapon ever detonated. It was detonated in the Soviet Union in 1961, of the way that fusion bombs work. As they actually have basically a bunch of fission bombs going off that wants to create enough pressure to make the hydrogen atoms fuse just the fission bombs that made this our bomb go off was equivalent to 50 megatons of TNT – the amount of stuff that was fused in the Tsar Bomba was about... that big. By contrast the area of the Sun where fusion is happening is about the size of 240,000 Earth, so if the Sun were to blow up all at once – like the Tsar Bomba did – it would basically melt everybody's faces off from here to Alpha Centauri. So the Sun and the Tsar Bomba are basically the same thing on different scales. Question is: why doesn't the Sun blow up all at once? Lucky for us, some naturally controls its pressure and its temperature and its fusion rate in the kind of natural thermostat. Basically, when the enormous heat and explosive energy in the corn make it expand, the core becomes less dense which makes the fusion rate slowed down and then gravity pulls the core back in, and starts all over again and that's just the way the Sun rolls. That's not to say that some stars don't blow their water all at once or at least a lot faster. Our Sun happens to be a G-type star, which is a tasteful middle of the road kind of mass for a star. As it happens the less massive star has the dimmer it is the redder it is and the longer lived it is. Team red dwarf, for example, can take trillions of years to burn out. While one of those big, blue O-type stars can burn through its entire allowance of hydrogen and like 1 million years. So, our Sun is doing pretty good. It looks like it's got another 4.5 billion years or so before it – you know – sputters out. How good old Sun... I miss it. Thanks for watching and learning during this SciShow dose. If you wanna have more of this you could subscribe at youtube.com/scishow. What else is going on? Oh, yeah, you can hook up as a lot of Facebook and Twitter. If you have any questions or ideas and ,of course, down in the YouTube comments below.