[ music] The Milky Way – home to billions of suns, rising and determining over billions of worlds, including our own. In this vast expanse, how did our Sun, the Earth, and countries around the world come to be? In recent decades, our understanding of the solar system’s growth has greatly improved, but deep doubts continue. To answer those questions, astronomers are preparing to visit someplace very small. Asteroid Bennu. A lump of rock and organic matter, the early building block of the solar system, of Earth, of us. Bennu is a hour capsule, and its travel takes us path, path back…four and a half billion years. The raw parts of Bennu, and our solar system, originated in a stellar nursery: a immense gloom of hydrogen, helium, and junk.
Our own Sun doesn’t yet exist. Nearby are red-hot suns like this one, promptly burning up its fuel…
and destroying itself in a gargantuan explosion called a supernova. The blowup destabilizes our gloom, justification it to collapse. In the geologic blink of an eye, a hundred thousand years, gravitation and angular momentum flatten the gloom into a swirling disc. In the centre for human rights, where molecules crash together tightest, a proto-star revs up to unbelievable pressings and temperatures. Deep within the disc, globs of junk not much larger than a particle 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 gravitation and agitation, the chondrules knot. They grow into the first asteroids, into mountains, into planets.
The asteroids are rubble slews of rock, metal, ice and organics. This large asteroid is the mother body of Bennu, a proto-planet whose size we can only guess. Closer to the proto-star, a planet have started to figure. And then…dawn in the solar system. The proto-star undergoes fusion and ignites, disclosing our Sun. But the solar system is far from finished. Jupiter most probably forms near its outer rim, but simply 500 million years after the Sun ignites, some believe that it gradually moves inward.
Its massive gravitation ripples the asteroid belt, disrupting countless asteroids and comets, flinging them toward the Sun. They rain down on the inner planets, hammering and re-melting large portions of their layer. Did these impacts also deliver organics and water, key ingredients for life? Back in the asteroid belt, Bennu’s parent body is luck, it exists this period of heavy bombardment.
The solar system cools and pacifies. Jupiter and its many moons presume the paths that we see today. Billions of years of quiet follow …[ impact] more or less. Then a billion years ago, one speculation recommends a collision shatters the proto-planet.[ loud blowup] Some of the rubble loosely coalesces into a brand-new, smaller body: Bennu. But Bennu will not stay in place. Dull , non-reflective, it gradually migrates toward the Sun. Solar heating becomes its warm back into a low-intensity thruster. Through millions of years, Bennu’s orbit gradually stiffens, until it interacts with Saturn’s gravity, adjusting its trajectory and lunging it into the inner solar system.
Close encounters with Earth and Venus follow.
Their gravitational tugs may have repeatedly stretched and reformed Bennu … transforming it inside out and pulling off loose fabric. As a answer, 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 lived its long travel and settled into a near-Earth path, fetching its secrets within our reach. Now it is ready to school us more about the solar system’s history, its formation, its growth, and our own region among the stars.[ music disappearances][ satellite beeping ].