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  • The Solar system. Our home in space.

  • We live in a peaceful part of the Milky Way.

  • Our home is the Solar system,

  • a 4.5-billion-year-old formation that races around the galactic centre at

  • 200,000 km/h and circles it once every 250 million years.

  • Our star, the Sun, is at the centre of the Solar system.

  • It’s orbited by eight planets,

  • trillions of asteroids and comets and a few dwarf planets.

  • The eight planets. Divided into four planets like ours:

  • Mercury, Venus, Earth and Mars,

  • and four gas giants: Jupiter, Saturn, Uranus and Neptune.

  • Mercury is the smallest and lightest of all the planets.

  • A Mercury year is shorter than the Mercury day, which leads to

  • enormous fluctuations in temperature.

  • Mercury does not have an atmosphere or a moon.

  • Venus is one of the brightest objects in the Solar system and by far

  • the hottest planet, with atmospheric pressure that is

  • 92 times higher than on Earth.

  • An out-of-control greenhouse effect means that Venus never

  • cools below 437 °C.

  • Venus also doesn’t have a moon.

  • Earth is our home and the only planet

  • with temperatures that are moderate enough to allow for a surplus of liquid water.

  • Furthermore, it’s so far the only place where life is known to exist.

  • The Earth has one moon.

  • Mars is the second smallest planet in the Solar system

  • and hardly massive enough to keep a very thin atmosphere.

  • Its Olympus Mons is the largest mountain in the Solar system,

  • more than three times as high as Mount Everest.

  • Mars has two small moons.

  • Jupiter is the largest and most massive planet in the Solar system.

  • It consists largely of hydrogen and helium

  • and is the theatre for the largest and most powerful storms we know.

  • Its largest storm, the Great Red Spot, is three times as large as Earth.

  • Jupiter has sixty-seven moons.

  • Saturn is the second largest planet and possesses the smallest density

  • of all the planets.

  • If you had a sufficiently large bathtub, Saturn would swim in it.

  • Saturn is also known for its extended, very visible ring system.

  • It has sixty-two moons.

  • Uranus is the third largest planet and one of the coldest.

  • Of all the gas giants, it’s also the smallest.

  • The special thing about Uranus is that its axis of rotation

  • is tilted sideways in contrast to the seven other planets.

  • It has twenty-seven moons.

  • Neptune is the last planet in the Solar system and is similar to Uranus.

  • It’s so far removed from the Sun that a Neptune year is 164 Earth years long.

  • The highest wind speed ever measured was in a storm on Neptune,

  • at just under 2,100 km/h.

  • Neptune has fourteen moons.

  • If we compare the sizes of the planets,

  • the differences between them become even clearer.

  • Jupiter is the leader in terms of size and weight;

  • small Mercury, on the other hand,

  • is even smaller than one of Jupiter’s moons, Ganymede.

  • Jupiter is so massive that alone it contains roughly 70% of the mass

  • of all the other planets and has a massive impact on its surroundings.

  • That’s a blessing for Earth, since Jupiter draws most of

  • the dangerously large asteroids that could wipe out life on Earth.

  • But even Jupiter is a dwarf in comparison to our star, the Sun.

  • Calling it massive does not do justice to the Sun.

  • It makes up 99.86% of the mass in our Solar system.

  • For the most part, it consists of hydrogen and helium.

  • Only less than 2% is made up of heavy elements, like oxygen or iron.

  • At its core, the Sun fuses 620 million tons of hydrogen each second

  • and generates enough energy to satisfy mankind’s needs for years.

  • But not only the eight planets orbit our Sun.

  • Trillions of asteroids and comets also circle it.

  • Most of them are concentrated into two belts:

  • the asteroid belt between Mars and Jupiter

  • and the Kuiper belt at the edge of the Solar system.

  • These belts are home to countless objects, some as large as a dust particle,

  • others the size of dwarf planets.

  • The most well-known object in the asteroid belt is Ceres;

  • the most well-known objects in the Kuiper belt are Pluto, Makemake and Haumea.

  • Usually we describe the asteroid belt as

  • a dense collection of bodies that constantly collide.

  • But in fact, the asteroids are distributed across an area that is

  • so indescribably large that it’s even difficult to see two asteroids at once.

  • Despite the billions of objects in them,

  • the asteroid belts are fairly empty places.

  • And nonetheless, there are collisions over and over again.

  • The mass of both belts is also unimpressive:

  • the asteroid belt has a little less than 4% of our Moon’s mass, and

  • the Kuiper belt is only between one 25th and one 10th of Earth’s mass.

  • One day, the Solar system will cease to exist.

  • The Sun will die, and Mercury, Venus and maybe Earth too will be destroyed.

  • In 500 million years it will become hotter and hotter until at some point

  • it will melt Earth’s crust.

  • Then the Sun will grow and grow and either swallow Earth

  • or at least turn it into a sea of lava.

  • When it has burnt up all its fuel and lost most of its mass,

  • it will shrink to a white dwarf and burn gently for a few billion more years

  • before it goes out entirely.

  • Then, at the latest, life in the Solar system will no longer be possible.

  • The Milky Way will not even notice it.

  • A small part of it in one of its arms will become just a tiny bit darker.

  • And mankind will cease to exist or leave the Solar system

  • in search of a new home.

  • Subtitles by the Amara.org community

The Solar system. Our home in space.

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