Comets, Asteroids, and Meteoroids

Year Giuseppe Piazzi discovered the first asteroid, Ceres 1801 Year Giuseppe Piazzi discovered the first asteroid, Ceres

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

2880 Year 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

The gigantic Chicxulub Crater (~110 miles diameter) in the Gulf of Mexico near the Yucatan Peninsula is about 65 million years old. (This is the one that may be connected with the extinction of the dinosaurs.)

Percentage of Asteroids Albedo (reflectivity) What are they made of? Type Composition Percentage of Asteroids Albedo (reflectivity) Carbon (C-type) Carbon over 75 percent 0.03-0.09 (Very dark) Silicate (S-type) Metallic iron mixed with iron-silicates and magnesium-silicates 17 percent 0.10 -0.22 (Relatively bright) Metallic (M-type) Iron/ nickel less 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)

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

Winter and early spring of 1997 Comet: Hale-Bopp www.brainpop.com/science/space/comets/ Winter and early spring of 1997 Next sighting: 4380

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.

There are three major types of meteorites: stone, iron and stony-iron. 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. SUMMARY 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.