Comets and AsteroidsComets and Asteroids

BY Travis MazzaBY Travis Mazza

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Mack PekarMack Pekar

CometsComets Comets are small, fragile, Comets are small, fragile,

irregularly shaped bodies irregularly shaped bodies composed of a mixture of composed of a mixture of non-volatile grains and frozen non-volatile grains and frozen gases. gases.

They have highly elliptical They have highly elliptical orbits that bring them very orbits that bring them very close to the Sun and swing close to the Sun and swing them deeply into space, often them deeply into space, often beyond the orbit of Pluto.beyond the orbit of Pluto.

As comets approach the Sun As comets approach the Sun they develop enormous tails they develop enormous tails of luminous material that of luminous material that extend for millions of extend for millions of kilometers from the head, kilometers from the head, away from the Sun.away from the Sun.

Cont.Cont. develop a surrounding cloud develop a surrounding cloud

of diffuse material, called a of diffuse material, called a coma, that usually grows in coma, that usually grows in size and brightness as the size and brightness as the comet approaches the Sun. comet approaches the Sun. Usually a small, bright Usually a small, bright nucleus (less than 10 km in nucleus (less than 10 km in diameter) is visible in the diameter) is visible in the middle of the coma. The coma middle of the coma. The coma and the nucleus together and the nucleus together constitute the head of the constitute the head of the comet. comet.

When far from the Sun, the When far from the Sun, the nucleus is very cold and its nucleus is very cold and its material is frozen solid within material is frozen solid within the nucleus. In this state the nucleus. In this state comets are sometimes comets are sometimes referred to as a "dirty referred to as a "dirty iceberg" or "dirty snowball"iceberg" or "dirty snowball"

Cont.Cont. The evaporated molecules boil off The evaporated molecules boil off

and carry small solid particles and carry small solid particles with them, forming the comet's with them, forming the comet's coma of gas and dust coma of gas and dust

As the comet absorbs ultraviolet As the comet absorbs ultraviolet light, chemical processes release light, chemical processes release hydrogen, which escapes the hydrogen, which escapes the comet's gravity, and forms a comet's gravity, and forms a hydrogen envelopehydrogen envelope

The tail of the comet stays away The tail of the comet stays away from the sun because of the solar from the sun because of the solar winds of the sun blowing the tail winds of the sun blowing the tail awayaway

AsteriodsAsteriods Asteroids are rocky and Asteroids are rocky and

metallic objects that orbit the metallic objects that orbit the Sun but are too small to be Sun but are too small to be considered planets. considered planets.

They are known as They are known as minor minor planetsplanets

Asteroids range in size from Asteroids range in size from Ceres, which has a diameter Ceres, which has a diameter of about 1000 km, down to of about 1000 km, down to the size of pebbles. Sixteen the size of pebbles. Sixteen asteroids have a diameter of asteroids have a diameter of 240 km or greater240 km or greater

Most, are found in the main Most, are found in the main belt that exists between the belt that exists between the orbits of Mars and Jupiterorbits of Mars and Jupiter

Cont.Cont. Asteroids are material left over from the formation of the solar systemAsteroids are material left over from the formation of the solar system One theory suggests that they are the remains of a planet that was One theory suggests that they are the remains of a planet that was

destroyed in a massive collision long agodestroyed in a massive collision long ago

Asteroids that are on a collision course with Earth are called meteoroids.Asteroids that are on a collision course with Earth are called meteoroids.

Work CitedWork Citedhttp://encke.jpl.nasa.gov/index.htmlhttp://encke.jpl.nasa.gov/index.html

http://www.solarviews.com/ss.htmlhttp://www.solarviews.com/ss.html