Remnants of Rock and Ice

• Asteroid: a rocky leftover planetesimal

• Comet: an icy leftover planetesimal

• Meteoroid: a planetesimal or other object that lands on Earth– Meteor (shooting star): a flash of light caused

by a meteoroid entering the atmosphere– Meteorite: a piece of meteoroid that reaches the

ground (rocky or metallic material)

Cratering by Meteoroid

Measuring Mass of an Asteroid

Primitive (Mixed) Meteorites

Processed Meteorites

Asteroid Location

Questions:

• Where did all the leftover planetesimals outside the belt go?

• Why are there Trojan Asteroids?

• Why are there asteroids in the belt instead of another planet?

Orbital Resonance

Asteroid Hunting

Asteroids Materials

Rotation and Shape of Asteroids

The Biggest Asteroids

Comets

• Comets melt when they come within 5 AU of the Sun.

• Ice sublimates forming the coma (gas and dust atmosphere)

• Two tails caused by material from coma

• Dust tail caused by sunlight and plasma tail caused by solar wind

Comet Orbits

Sources of Comets

Pluto and Its Moon

Pluto’s Closest Approach

Orbits of Pluto and Charon

Pluto and Charon

Pluto in True Color

Large Impactor

Rate of Impactors

Meteor Showers