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3-6 Asteroids

3-6 Asteroids. Jupiter. Asteroid belt. Earth. Asteroids: rocky or metallic. They contain little volatile (i.e. easily evaporated) material. Gaspara. Ida and its satellite Dactyl. Belt asteroids – by Galileo spacecraft. They differ from planets by their size.

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3-6 Asteroids

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  1. 3-6 Asteroids

  2. Jupiter Asteroid belt Earth

  3. Asteroids: rocky or metallic. They contain little volatile (i.e. easily evaporated) material Gaspara Ida and its satellite Dactyl Belt asteroids – by Galileo spacecraft

  4. They differ from planets by their size

  5. January 1801: Giovanni Piazzi thinks he has found a new planet between Mars and Jupiter: Ceres Artist view HST By 1890, more than 300 such “planets” had been discovered

  6. 1890: Introduction of photography to the search for asteroids Asteroid trail: asteroids move relative to the stars

  7. Today more than 20,000 asteroids have well-determined orbits We estimate that there are more than a million asteroids with diameters larger than 1 km

  8. The mass of all the asteroids is less than the mass of the Moon Asteroid belt: the typical spacing between two asteroids larger than1 km is several million kilometers

  9. Majority: as dark as a lump of coal, made of rock Primitive bodies dating from solar system formation Some reflect 60% of the incoming sunlight, composed of metal Come from a large body with molten interior that was shattered by a collision

  10. Trojan asteroids If you put an asteroid on the Earth orbit, would it: Stay on the orbit? Drift away? Crash into our planet?

  11. It depends on where you place the asteroid. There are five points, known as the Lagrange points, where an asteroid will remain stationary with respect to the Earth Asteroids placed anywhere else will drift around in various ways

  12. The most stable positions are L4 and L5:

  13. Jupiter’s L4 and L5 asteroids are named after Trojan heroes, so we call them ‘Trojan asteroids’ The name Trojan is now used for any other planet: “Earth Trojans”

  14. Launched 1996 Near Earth Asteroid Rendezvous: NEAR

  15. Eros Impact craters

  16. Eros Loose material Dotted with half buried boulders

  17. NEAR: last images (Feb 2001) 250 m 120 m Lost signal amazing profusion of boulders collapse feature, formed when support is removed from below the surface

  18. Terrestrial planets: self-assessment quiz

  19. DEATH CAP

  20. SIMPSONS

  21. CAMEMBERT

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