Asteroids

Asteroid Belt Between Mars and Jupiter there are a number of objects. Much smaller than a planet The small amount of light led them to be named asteroids. Jupiter’s gravity keeps asteroids from growing too large. Mars’ orbit Main belt Jupiter’s orbit

Minor Planets 26 asteroids have diameters greater than 200 km. Largest: Ceres, 933 km Large asteroids show some differentiation into layers like a planet, including lava flows.

Types of Asteroids C-type S-type M-type 75% of asteroids extremely dark (albedo 0.03) oldest material, carbon and other minerals. S-type 17% of asteroids bright (albedo 0.10 to 0.22) iron mixed with silicate rock. M-type 8% of asteroids bright (albedo 0.10 to 0.18) pure iron with nickel and other metals.

Mathilde Mathilde is a main-belt asteroid (66 km long). Dark type C Craters with little splash NEAR/Mathilde

Trojan Asteroids The law of gravity permits an orbit around the sun exactly 60º ahead of and behind Jupiter, called Lagrange points. Asteroids collect there Several hundred Trojan asteroids locked to Jupiter L4 Trojans Jupiter L5 Trojans

Near Earth Asteroids Asteroids nudged by Jupiter’s gravity head into the inner solar system. Many of these now have orbits that cross the orbit of Earth.

Eros Eros is a near-earth asteroid (30 km long). Bright type S Impact boulders on its surface The NEAR spacecraft also visited here, and safely touched down on the surface. NEAR/Eros