This is called the heavy bombardment.
Fates of the Planetesimals: Ejec9on or Collision ‣ Outer planetesimals had gravitational interactions with the young Jovians ‣ Changed their orbits ‣ Totally ejected from the solar system, OR... ‣ Ejected them to the far reaches of the solar system, OR... ‣ Sent them into the inner solar system to collide with terrestrials Outer planetesimals were scattered outward and inward Unaffected region Ejected to large distances (Oort Cloud) Totally ejected out of the Solar System and inward toward the Sun Sun J S U N 24 Face-on view of the young outer solar system. The objects near Jupiter were scattered out of the solar system, or inward toward the Sun. Those between Saturn and Uranus are believed to have been tossed outward to populate the Oort Cloud. Those beyond Neptune were not significantly a ff ected, and remain today as Kuiper Belt Objects
Cosmic Water Water may have come to Earth by way of ice- rich planetesimals from the outer solar system NASA/JPL-Caltech 25 This artist's conception illustrates a storm of icy planetesimals - comets. One is shown smashing into a rocky planet, flinging ice- and carbon-rich dust into space, while also smashing water and organics into the surface of the planet. A glowing red flash captures the moment of impact on the planet. The Sun is shown to the left, with still more comets streaming toward it. The incoming comets scarred our moon and pummeled our inner planets. They may have even brought materials to Earth that helped kick start life.
Asteroids and comets are the leXover planetesimals! Comets are icy because they formed outside the frostline Asteroids are rocky because they formed inside the frostline NASA NASA 26 The asteroids seen today are the last remains of those rocky planetesimals. Icy planetesimals ejected to the far reaches of the solar system form the Oort Cloud, a spherical distribution of trillions of icy planestimals perhaps 50,000 AUs in diameter. The icy Kuiper belt objects, including Pluto, appear to be ancient planetesimals. They formed in the outer solar system but were never incorporated into a planet. They orbit slowly far from the light and warmth of the sun. Except for occasional collisions, they have not changed much since the solar system was young.
Did the Moon form due to a collision of the young Earth with a planetesimal? Image credit: NASA/JPL-Caltech The most widely accepted theory of the Moon’s formation is the giant impact theory 27 There have been a variety of scenarios proposed to explain the di ff erences between the Moon and Earth. The one that has gained acceptance after much study is the giant impact theory developed by Hartmann and Davis in the mid-1970s.
The Giant Impact Theory Image: Nick Strobel, 28 The giant impact theory proposes that 50 million years after the Earth formed, a large Mars-sized object hit the Earth and blew mantle material outward, some of which later recoalesced to form the Moon. Most of the mantle material from the Earth and the giant impactor combined to make a larger Earth. Such an impact was rare so is was not likely to have also occurred on the other
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- Spring '08
- Solar System, Planet, solar nebula