A minute planet; a body that could or did come together with many others under gravitation to form a planet.
- Asteroids are small bodies in space - the numerous leftover planetesimals from which the planets were made nearly 4.6 billion years ago.
- Although planets, moons and planetesimals may seem to be very different astronomically, their common origin shows that this is not so.
- As planetesimals grow still larger, their gravitational attraction increases, allowing them to become even more effective at accreting nearby planetesimals.
Relating to planetesimal bodies.
- Models of planetesimal disks suggest that low relative velocities between the bodies produce accretion (objects hit and stay together) rather than fragmentation (objects break up and disperse).
- His greatest contribution, however, was his planetesimal hypothesis of the origin of the planets.
- After all, planetesimal sized portions of the Solar System cannot be considered to be orbiting the Earth, except in the obvious case of the Moon.
Early 20th century: from planet, on the pattern of infinitesimal.
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