The Formation of the Solar System in 4K (Ultra HD)

Bryce: This is the story of our Earth’s
formation four-and-a-half billion years ago, and of a little asteroid called Bennu, who’s
also survived until now. We have the team at NASA to thank for bringing us this video. NASA narrator: The Milky Way, home to billions
of stars, rising and setting over billions of worlds, including our own. In this vast
expanse, how did our Sun, the Earth, and the planets come to be? In recent decades, our
understanding of the solar system’s evolution has greatly improved, but deep questions remain.
To answer those questions, astronomers are preparing to visit someplace very small: asteroid
Bennu. A lump of rock and organic material the early building blocks of the solar system—of
Earth, of us. Bennu is a time capsule, and its journey takes us way, way back, four-and-a-half
billion years. The raw ingredients of Bennu, and our solar system, originated in a stellar
nursery—a vast cloud of hydrogen, helium, and dust. Our own sun doesn’t yet exist.
Nearby are hot stars like this one, quickly burning up its fuel and destroying itself
in a colossal explosion called a supernova. The explosion destabilizes our cloud, causing
it to collapse. In the geologic blink of an eye, 100,000 years, gravity and angular momentum
flatten the cloud into an exploding disc. In the center, where molecules crash together
tightest, a protostar revs up to incredible pressures and temperatures. Deep within the
disc, clumps of dust not much larger than a grain of wheat are flash-heated into droplets
of molten rock called chondrules. The source of this heat remains a mystery. Chondrules
are destined to become the building blocks of the solar system. Coaxed by gravity and
turbulence, the chondrules clump. They grow into the first asteroids, into mountains,
into planets. The asteroids are rubble piles of rock, metal, ice, and organics. This large
asteroid is the parent body of Bennu, a protoplanet whose size we can only guess. Closer to the
protostar a planet begins to form. And then, dawn in the solar system. The protostar undergoes
fusion and ignites, revealing our sun, but the solar system is far from finished. Jupiter
most-likely forms near its outer edge. But just 500 million years after the sun ignites,
some believe that it slowly moves inward, its massive gravity ripples the asteroid belt,
disrupting countless asteroids and comets, flinging them toward the sun. They rain down
on the inner planets, hammering and remelting large portions of their crust. Did these impacts
also deliver organics in water, key ingredients for life. Back in the asteroid belt, Bennu’s
parent body is lucky, it survives this period of heavy bombardment. The solar system cools
and calms. Jumper and its many moons assume the orbits that we see today. Billions of
years of quiet follow, more or less. Then a billion years ago, one theory suggests,
a collision shatters the protoplanet. Some of the debris loosely coalesces into a new
smaller body: Bennu. But Bennu will not stay in place. Dull, non-reflective, it slowly
migrates toward the sun. Solar heating turns its warm side into a glowing low-intensity
thruster. Through millions of years, Bennu’s orbit gradually tightens until it interacts
with Saturn’s gravity, altering its trajectory and hurling it into the inner solar system.
Close encounters with Earth and Venus follow. Their gravitational tugs may have repeatedly
stretched and reformed Bennu, turning it inside-out and pulling off loose material. As a result,
it has no satellites of its own, until now. Today, NASA is sending a spacecraft called
Osiris Rex to explore Bennu and retrieve a sample. Why? Bennu has survived its long journey
and settled into a near-earth orbit, bringing its secrets within our reach. Now it is ready
to teach us more about the solar system’s history, its formation, its evolution, and
our own place among the stars.

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