What’s That Up In The Sky??? The difference between Comets, Meteors and Asteroids

Comets………Dirty Balls of Ice They look like a star with a ghostly white tail. The term "comet" derives from the Greek aster kometes, which means "long-haired star"---a reference to the tail.

Comets………Dirty Balls of Ice They can be seen by us only when they pass by the sun and the sun’s heat melts them. The comet's tail is made of material from the comet; gas from the ices and dust that is mixed in with the ice. They escape as the comet melts. The icy, hard part of the comet is called the nucleus. The gas and dust are released and form an atmosphere around the comet called the coma. The tail always points away from the sun due to the solar winds (movement of heat away from sun)

Comets………Dirty Balls of Ice If a comet has a large orbit, it takes a long time to go around the Sun. Some comets are "short-period" comets that take five or ten years to complete an orbit. Some comets are "long-period" comets that take decades, centuries, or millenia to orbit the Sun.

Asteroids……Rockin’ Around Asteroids are LARGE chunks of rock and metal that orbit the sun. They range from just over ½ a mile (1km) to a few hundred miles in diameter (diameter = how wide across)

Asteroids……Rockin’ Around Most asteroids travel in the wide gap between the inner planets and outer planets (between Mars and Jupiter). But a few travel in paths across Mar’s orbit and some even cross in Earth’s orbit.

Asteroids……Rockin’ Around Most of the chunks or rock and metal in space came together long ago to form the planets and moons. Asteroids are left-over pieces of rock from when the solar system was formed (“Big Bang”).

Meteors…Shooting Stars or Space Garbage Meteoroids Pieces of rock or metal that travel in orbits around the sun. Meteors Pieces of rock/metal that are falling through the Earth’s atmosphere from space. Meteorites Pieces of rock/metal that have survived the heat caused from the friction of traveling through the atmosphere and have HIT THE GROUND.

Meteorite composition Major groupings: Stony meteorites Chondrites Achondrites Iron meteorites Stony-iron meteorites 9

Chondrites Stony meteorites – most common meteorites and represent the oldest solids that are the building blocks of the solar system Contain up to 80% chondrules Chondrule- fragments that make up the chondrite Subtypes: Breccia- VERY large chondrules Carbonaceous chondrites dark because of the materials present 10

Achondrites NO Chondrules are present because the materials have been heated and pressurized melting it together. Similar to igneous rock (colors and lines are determined by the minerals in the meteorite). The Johnstown Diogenite. Lunar Meteorite Allan Hills 81005 11

Is there a fusion crust present? Fusion crust forms on entry through the atmosphere. It looks like an outer coating. 12

Identifying a meteorite Are there visible chondrules (large fragments)? What color is the meteorite? Is there a fusion crust? Fusion crust forms during entry into the atmosphere. The heat melts the outside of the meteorite forming a “crust.” 13

Barringer Meteor Crater, Arizona, formed from Canyon Diable Meteorite Impact Craters Barringer Meteor Crater, Arizona, formed from Canyon Diable Meteorite 14

Impact Craters Craters formed when a meteorite hits a solid surface on the Earth. Size and depth will depend on the size of the meteorite and the speed it is falling. Many meteorites will break into fragments upon impact. The type of surface will determine how far they scatter and how easy it is to find the pieces. It is easier to find meteorite fragments in snow and sand It is harder to find meteorite fragments in rocky areas or grassy fields. Clearwater lakes, Quebec – 36+26km diameter, 290 ma 15

What’s That Up In The Sky??? COMETS ASTEROIDS METEORS Made of ice-have tails Made of rock and metal Stay in space Fall into Earth’s atmosphere Orbit the sun Gravity pulls to Earth; they burn up as they fall

What's the difference between meteoroids, meteors, and meteorites? http://www.faqs.org/faqs/astronomy/faq/part5/section-29.html