1. Asteroids

2. 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

3. 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.

4. 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.

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

6. 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

7. 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.

8. 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