Name: Yuri Gagarin and Orbits - Sixty Symbols
Uploaded: 2020-03-30T04:13:46.000Z
Duration: 7 min 13 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

Adverbs of manner

April 2011 is the 50th anniversary off the first man in space on the first complete orbit of the Earth by ah manned spacecraft, but also was the first example where we were actually able to use the sort of theory of orbits to actually for a practical application to actually put somebody into space.

The person in question was, uh, Soviet back to call him a Russian.

But of course at the time, and the Soviets guy called Yuri Gagarin.

So he launched from the Baikonur cosmodrome in Kazakhstan on headed to the east and actually almost a ll.

Satellites and spacecraft get launched to these because that's the way the earth rotating.

So you actually kind of get a kick from the Earth's rotation, which helps you on your way on.

Then through all the way around the earth, came back across the Pacific round on, then landed fairly close to where we launched in the first place.

You look at it on a map, he doesn't actually quite get back to where we started, so you might think he hadn't completed a complete orbit of the Earth.

But of course, in the meantime, while he was flying around the earth have been rotating on.

So actually where he landed was sort of directly where he took off in the first place.

In the meantime, it's a bit difficult to see these things on a map because, of course, what he was really doing was flying about the circular globe of the Earth on was following Maura lesser sort of, ah, circular orbit around the Earth.

But of course, as soon as you unwrap that and have to project it onto a flat piece of paper to make a map, you always end up with these rather strange looking bendy parts.

But after his orbit was reasonably simple, it was quite close to a circle around the earth.

So, in fact, although this was the first time that anyone had actually put this theory into practice, the ideas go back on a very long way.

And really the first person who had figured out what orbits were about it was Isaac Newton.

It was actually part of his Principia, where we figured out the nature of gravity and so on along the way in that he figured out how orbits actually work.

And it was actually even thinking about the way the gravity works and on the orbit of the moon, which actually led to his full understanding of gravity in the first place.

And he had a rather neat sort of analogy.

He used to sort of thought experiment needed to explain how orbits actually work, which is his thought.

Experiment was if you took a cannon on, hold it up to the top of a very high mountain on fire, the cannon ball out horizontally.

What he knew it would go forward, and it would sort of fall slowly to Earth.

If you then put more gunpowder into the cannon and crank things up a bit and fire the cannon ball, it would obviously got a bit further before it fell to Earth.

But the other thing he realized that actually, it would even go a little bit further than you expected, because as the cannonball force to the wars, the Earth, of course, there's a curvature of the earth as well.

So the cannonball act it goes even further before it finally catches up with where the ground is.

Andi was great Leap was to say Okay, so let's put even more gunpowder into this cannon.

And if I fire it with enough force, then the Cannonball Wolf indeed, be falling to Earth.

But the curvature of the earth will guarantee that the cannonball Force kind of towards the earth at exactly the same right that the earth is falling away.

That's all of the cannonball is always falling towards the earth.

He never gets any closer to the earth because the U.

S curvature is taking it away from where it might land at the same rate.

If you put a little bit more gunpowder and you'll end up on the elliptical orbit originally your initiative, you're kind of head away from the earth, and then eventually you come back around again, so you'll follow an ellipse rather than a circle.

And if you put even more gunpowder in than that, you actually escaped from the Earth entirely and eventually go into deep space.

The reason why this was only kind of a thought experiment on rather rather than an actual practical experiment is because it turns out there's two things.

Firstly, if you actually did this at the top of a mountain.

It wouldn't work because air resistance would slow down your cannonball more than anything else.

And so the cannonball would heat up and slow down the Fort Worth.

So you can't put things into orbit that close to the ground because the U.

S atmosphere heats up whatever's flying through them and stops it staying in orbit.

But the other problem is sort of a more practical one that if you actually figure out how fast you'd actually need your cannonball to emerge from the gun in order to go around on this orbit in this sort of low earth orbit, were you very close to the Earth?

It needs to be going at and in fact, a modern bullet rifle bullet goes in about one kilometer per second.

So this is a much farther than anything you could actually practically do with a cannon then.

But even with a gun now, it really wouldn't work.

So the trick is obviously to get away from the atmosphere which is causing all this friction s So that's what the first part of the trick and then the other part of the trick is to have something that gets you up to these ridiculously high speeds of six or seven kilometers per second that needed the invention of the rocket engine, which really provides rather than with a cannon.

You get this single pulse that boost you to a certain speed but a rock, It really allows you to kind of Dr upto high, high enough speeds to really go into orbit.

It was a truly astounding achievement, but obviously one of the things that people were kind of excited about was whether this whether he really had completed in orbit, But it turns out they're actually rules.

I found out about this that even in 1961 somebody had made up rules as to what would constitute this achievement on one of the rules.

For whatever reason they come up with was the fact that the astronauts had to stay in their space, craft the entire journey and landing their spacecraft takeoff and landing it.

And one of the things that actually happened it was part of the design of the mission was that guardian actually parachuted out.

He completed re entry and then before the thing hit the ground.

He actually parachuted out because it was deemed safer to land on a parachute that the land in the space probe Onda course.

Officially, this means that he wouldn't have broken the record.

He wouldn't have achieved the first orbit of the Earth on the Soviets.

Actually lied about this for a long time.

For about a decade afterwards, they pretended that he'd actually landed in the spacecraft, and he was made to say that he landed in the space problems.

So they got the record officially given to them.

And only about in the 19 seventies did they actually admit what?

By which point nobody really cared very much.

So Gagarin was on what was known as a low earth orbit because, really, at the time, all you could do was get a rocket just above the atmosphere, and that gets you into an orbit.

That's kind of the lowest one that you could do around the earth a couple of 100 kilometers up on when you were that couple 100 kilometers up.

It's actually not that far around the earth and you going very fast, eh?

So it works out that It takes about 90 minutes to go around the Earth.

But obviously you can go into orbit in principle that any distance away from the earth.

So there's a whole series in different orbits that get used nowadays.

Perhaps the most famous is a thing called the Geo stationary orbit, where if you get up to about 36,000 kilometers above the Earth, the speed at which you need to go around get slower as you get further away because the pull of gravity is getting smaller on actually got further to go, so actually takes longer to complete the orbit.

A CZ well on at this magic distance of 36,000 kilometers on orbit takes exactly 24 hours or 23 hours and 57 minutes or so, basically exactly a day, which means that you're staying above the same point as you go around.

You're going around the Earth at exactly the same speed that the Earth is rotating, which means you stay above the same point on the Earth the entire way around.

And that's very useful for things like communication satellites, where you want them to stay about their ground station.

Or maybe where the satellites where you want to be monitoring a particular part of the earth.

And then, of course, if you take it even further, if you go out to 400,000 kilometres, then it actually takes about 28 days to go around entirely.

And, of course, that's the distance the moon is away from us.

And the reason why among this around 28 days, that's how long it takes the moon to complete one complete orbit of the Earth.

And that was really what Newton's great achievement eternal this world's was tying all this stuff of thinking about gravity at the surface of the earth and then applying it to the gravity at the distance of the moon and realizing they were really different aspects of the same thing.

A ll the things like the International Space station, the Hubble Space Telescope.

In those kinds of things, they're all in low earth orbits.

The only orbit the space shuttle can get up to is this low earth orbit.

 So anything that's been delivered into the space by the space shuttle and hasn't had a booster rocket to take it up to a higher orbit will end up in one of these low earth orbits. 