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Comets, Asteroids, and Meteoroids


Year Giuseppe Piazzi discovered the first asteroid, Ceres


Earth years it takes the asteroid Ceres to travel around the sun (Ceres ­ Biggest Asteroid with a 960 km circumference)


Year asteroid 1950 DA will pass close to Earth ­ The greatest known impact hazard


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


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


What are they made of?

Type Composition Percentage of Asteroids Albedo (reflectivity)

Carbon (C-type)


over 75 percent

0.03-0.09 (Very dark)

0.10 -0.22 (Relatively bright)

Silicate (S-type)

Metallic iron mixed with ironsilicates and magnesium-silicates

17 percent

Metallic (M-type)

Iron/ nickel

less than 7 percent

0.10-0.18 (Relatively bright) 0.05 (Relatively dark and reddish)

Dark (Dtype)

Water ice/frozen carbon monoxide mixed with rock

less than 1 percent

Asteroid Ida and the tiny moon Dactyl


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

Deep Impact colliding with Temple1

Organic compounds


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.


Meteoroids that survive as they pass through the atmosphere and hit Earth's surface are called meteorites.

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.

Now do this

In your journal, define Asteroid, Comet, Meteor, Meteoroid, and Meteorite. Compare and contrast all three using the Venn Diagram on the board.


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