Chapter 11: Meteoroids, Asteroids, and Comets

The Kuiper Belt of comets spreads from Neptune out 500 AU from the Sun

Kuiper Belt Objects

Oort Comet Cloud

A. icy dirtball?

B. dirty snowball?

or

Comets

Rosetta Mission

Rosetta Images

Composition of a Comet

Comets lack tails until they enter the inner solar system.

Composition of a Comet

Period of orbit is 75-76 yearspredicted by Edmond Halley

Nucleus very dark

Dirty snowball!

Halley’s Comet

“I came in with Halley’s comet in 1835.It is expecting to come again next year (1910), and I expect to go out with it.The Almighty has said no doubt: ‘ Nowhere are two unaccountable freaks; theycame in together, they must go outtogether.”

- Mark Twain, a Biography

Halley’s Comet and Mark Twain

Meteor Showers

Meteor Showers

The Great Leonid Storm of 1833

Meteor Showers

• meteoroids: chunks of matter in space orbiting in the Solar System ranging up to tens of meters across and sometimes larger

• meteors: when these chunks hit the Earth’s atmosphere and show up as streaks in the sky

• meteorite: when a fragment of a meteoroid survives its passage through the Earth’s atmosphere

Meteoroids

Meteorites

Meteorites

Gaspra

Ida and its moon Dactyl

Asteroids

Ceres was the largest Asteroid, now it’s a Dwarf Planet

Most asteroids orbit the Sun between Mars and Jupiter

Near Earth Asteroids cross the Earth’s orbit

Impact!

Tunguska Mystery, Siberia, 1908

Barringer Meteor Crater, Arizona 15000 years ago

Impact!

The Extinction of Dinosaurs

The Extinction of

Dinosaurs

Next Impact?