Comets, Asteroids, and Meteoroids

1801Year Giuseppe Piazzi discovered the first

asteroid, Ceres

4.6Earth years it takes the asteroid Ceres to travel around the sun (Ceres – Biggest Asteroid with

a 960 km circumference)

2880Year asteroid 1950 DA will pass close to Earth

– The greatest known impact hazard

Asteroids

Asteroids are small, rocky worlds. Most asteroids revolve around the sun between the orbits of Mars and Jupiter. (asteroid belt)

Asteroids

Earth has been struck many times in its history by asteroids.

This 142-million-year-old crater has a diameter of almost fourteen miles (twenty-two km). Like many craters on Earth, it is misleading. The raised ring that is clearly visible to the left is not the crater rim. It is an erosional remnant. The remains of the actual rim are found farther out from the ring.

•100 km

•212 Million years old

•Canada

Type CompositionPercentage of Asteroids

Albedo (reflectivity)

Carbon (C-type)

Carbonover 75 percent

0.03-0.09 (Very dark)

Silicate (S-type)

Metallic iron mixed with iron-silicates and magnesium-silicates

17 percent0.10 -0.22 (Relatively

bright)

Metallic (M-type)

Iron/ nickelless than 7

percent

0.10-0.18 (Relatively

bright)

Dark (D-type)

Water ice/frozen carbon monoxide mixed with rock

less than 1 percent

0.05 (Relatively dark and reddish)

What are they made of?

Asteroid Ida and the tiny moon Dactyl

Comets A comet is a “dirty snowball” about the size of an earth mountain. (dirt and ice)Comets’ orbits are usually very long, narrow ellipses. They produce tails of gas and dust when they approach the sun.

Halley’s Comet…. Orbits every 76 years

Halley’s Comet Orbit…next seen in 2062

Oort Cloud

Comet: Hale-Bopp

Winter and early spring of

1997

Next sighting: 4380

www.brainpop.com/science/space/comets/

Deep Impact colliding with Temple1

Organic compounds

Meteoroid

A meteoroid is a chunk of rock, metal, or dust in space.

A Meteor: “A shooting star”

Shooting stars are not actually stars. These flashes of light across the sky are small bits of rock burning up in the Earth’s Atmosphere.

Meteorite

Meteoroids that survive as they pass through the

atmosphere and hit Earth’s surface are called

meteorites.

http://www.meteorlab.com/METEORLAB2001dev/Open1.htm

There are three major types of meteorites: stone, iron and

stony-iron.

Barringer Meteor Crater, Arizona

A meteorite can make a hole, or crater, in the ground when it hits it. The larger the meteorite, the bigger the hole.

METEOROID: A piece of stone or metal that travels in outer space.

METEOR: An object from space that becomes glowing hot when it passes into Earth's atmosphere.

METEORITE: A piece of stone or metal from space that falls to Earth's surface.

SUMMARY