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  • (Incoming transmission from Phil Plait...) Welcome to our Solar System.

  • Below you will find our sun. Our star is 2 octillion tons of hot hydrogen gas emitting

  • 400 septillion joules of energy every second. The hottest part of the sun is its 15 million°C

  • core, where it's been fusing hydrogen into helium for the past 4.6 billions years. Despite

  • that, it's only considered a middle aged star!

  • Now let's check out the closest planet to our sun, Mercury. Orbiting the sun in just

  • 88 days, Mercury also has the most elliptical orbit of any planet. It spins very slowly,

  • once every 2/3 of its orbital period. Despite its surface reaching a blistering 430°C, it still has

  • water ice in permanently shadowed craters near its poles, where the temperatures stay below -170° C.

  • The next planet in our solar system is Venus. It's the planet with the hottest surface

  • temperature; at 460°C it's hot enough to melt lead. Its air is almost entirely composed

  • of carbon dioxide, with a thick layer of sulfuric clouds. Its rotational axis is flipped upside-down,

  • which means that the planet spins backwards.

  • The third and best understood planet is Earth. Our home planet has a dense metal core, a

  • thick viscous rock mantle, and a thin crust. It's unique in the solar system for having

  • humans and permanent liquid water on its surface. Other planets may get the former soon.

  • At 3470 km in diameter, our Moon has the largest moon-to-planet size ratio. It's thought to have

  • formed when a small planet impacted Earth at a grazing angle billions of years ago.

  • It's heavily cratered, and has huge flood plains on it called maria.

  • Next up in our system is Mars. Its iconic red color comes from its rusty rocks and dust.

  • In the past Mars was once very wet, with oceans, a thick atmosphere, and a warmer climate.

  • But its lack of a magnetic field meant no protection from the solar wind, which eroded its atmosphere away.

  • Between Mars and Jupiter is a large asteroid belt.

  • It's a ring shaped region containing rubble leftover from the formation of the planets.

  • Past the asteroid belt we find our systems Jovian planets, starting with Jupiter.

  • A gas giant, it's the largest planet in our solar system. It has a dynamic atmosphere, including

  • belts, zones, and a gigantic red spot created by a persistent hurricane. The Great Red Spot

  • is a persistent anticyclonic storm. The spot is large enough to contain three Earth-sized

  • planets. It's still unclear what exactly gives the spot its red color.

  • The next planet in our system is Saturn. It's a gas giant with a broad set of rings.

  • It has a hexagonal cloud pattern on its north pole. It's the least dense of all the planets,

  • even less dense than water! Made up of ice particles, Saturn's rings are 250,000 km across,

  • but only 10 meters thick! Gaps in the rings are created the gravitational tugging of the moons orbiting Saturn.

  • Uranus is an ice giant with a small rocky core and a thick mantle of ammonia, water, and methane.

  • It also has thirteen distinct rings. Uranus has a huge tilt -- 98°, with respect to its orbit.

  • A massive glancing collision long ago is one hypothesis to explain the extreme tilt.

  • Technically considered the last planet in our solar system, Neptune is an ice giant,

  • with a similar composition to Uranus. It's the most dense of the outer planets and the

  • only planet found by mathematical prediction rather than by empirical observation.

  • At the outer edges of our solar system we find the Kuiper Belt, filled with smaller rocky and icy bodies.

  • Pluto is in this region. It was originally discovered in 1930 and categorized as a planet,

  • but it was recategorized as a minor planet in 2006.

  • And there you go -- a crash course on our solar system. Even though we've explored a lot of it, there's still

  • a huge amount left to discover. And that's the beauty of science: there's always more to learn.

  • Thank you so much for watching! This video was created by the folks at Thought Café

  • who have their own channel with awesome animated videos. Make sure to check them out and subscribe.

  • Links below in the doobly-doo!

(Incoming transmission from Phil Plait...) Welcome to our Solar System.

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Explore The Solar System: 360 Degree Interactive Tour!

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    韓澐 posted on 2016/05/04
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