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  • it begins at a point in time.

  • Nearly 4.6 billion years ago, a giant cloud of gas and dust floats eerily through a remote arm of the Milky Way, chilled to more than 400 degrees below zero.

  • When it's sitting there all alone, nothing much is happening in a molecular clouds.

  • Temperatures are very low.

  • The particles are moving around very, very slowly.

  • It's just sitting there.

  • But if you have a nearby supernova, an exploding star, it can send a shockwave through this molecular cloud, triggering its gravitational collapse.

  • That collapse is the first step in a long process that brings the place we now call the solar system into existence.

  • The evidence of our past is all around us.

  • The four planets in the inner part of the solar system are made of rock and metal, and the four planets in the outer part of the solar system are these giant balls of gas.

  • So clearly different processes were at play, and that tells us something about how we got here.

  • Beginning as a cloud of gas and dust.

  • The making of our solar system will take 700 million years now, just two million years after its birth, young system takes its first steps and creating a family of planets that one day will be a diverse as Jupiter Saturday aboard the Earth.

  • For now, though, they air chunks of matter, continuing their roller coaster ride in the turbulence of the solar nebula.

  • The thick rotating disk, made mostly of hydrogen gas, is embedded with solids.

  • The inner zone is filled with small chunks of rock, but outside the boundary known as the Snow Line, there are also Isis of methane, ammonia and water, which dominate the outer disc.

  • And for good reason.

  • They're all hydrogen compounds of one form or another, and hydrogen is the most abundant element in that region of the solar system.

  • At that point, that abundant hydrogen is combining with elements such as oxygen to form the water or carbon to form the methane or nitrogen to form the ammonia and giving us those compounds, which have been freezing out.

  • Continual collisions amid the turbulence make tiny specks of dust and ice stick together through friction and static electricity until they're large enough for gravity to take over.

  • Eventually, they become planetesimals.

  • Planetesimals were the original building blocks of our solar system.

  • They're incredibly small, only about half a mile to a mile across.

  • But there were countless numbers in the early solar system.

  • It was simply littered with them.

  • These half mile planet testicles will eventually form full scale planets, but of distinctly different sizes.

  • The forming star had this huge solar wind that was clearing material out of the solar system.

  • Jupiter and Saturn were fortunate enough to pick up most of this material in their orbits, which is why they're so large.

  • Uranus and Neptune were a bit later to the game and were unable to pick up a CZ much material, which is why they're smaller than Jupiter and Saturn.

  • We're now with the most critical point in the making of our solar system.

  • At 50 million years old, the proto son and it's forming planets are barely 1% of their present age.

  • In many systems.

  • The Central Star doesn't have enough mass to fully ignite.

  • But our son is about to overcome that fate.

  • It has reached the critical threshold of heat and pressure where nuclear fusion could begin in its core, using the same awesome energy that powers the hydrogen bomb.

  • Our sun bursts into life as a fully formed newborn star about 50 million years into the life of the solar system.

  • Since it first began forming, the sun goes into a different phase.

  • Burning hydrogen actually doing nuclear fusion.

  • At that point, the sun becomes what we think over is now a fully fledged star.

  • Nuclear fusion will carry the sun into the distant future.

  • It will burn long enough to support the evolution of life on Earth, shining unceasingly for about 10 billion years.

  • Unlike the newly nuclear son, the rest of the solar system is far from mature.

  • 40 million years earlier, the frozen gas giants outside the snow line ceased to grow and achieved on icy stability.

  • But in the hot inner solar system, where guess is rare, but rocks abound, chaos still reigns.

  • For the time that the sun has become a full fledged star, the planets in the inner part of the solar system are still trying to grow.

it begins at a point in time.

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太陽系の成り立ち|宇宙(シーズン6)|歴史 (How the Solar System Was Created | The Universe (Season 6) | History)

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    林宜悉 に公開 2021 年 01 月 14 日
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