BY: IAN + SHAE

What is a Comet?

Small solar system body

Displays coma (a thin, fuzzy, temporary atmosphere) when close enough to the sun

Few kilometers across, and appear to mostly be composed of water, carbon dioxide, ammonia, and methane ices, with dust mixed in

Observed since ancient times

Parts of the comet

Coma • cloud of diffuse material surrounding the

comet, • usually grows in size and brightness as the

comet approaches the Sun.

Nucleus• small, bright (less than 10 km in diameter) • visible in the middle of the comaThe coma and

the nucleus together constitute the head of the comet

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Dust Tail• composed of dust particles liberated

from the nucleus as the ices are vaporized

Ion Tail• composed of ions blown out of the

comet away from the Sun by the solar wind

Cometary Orbits

Most comets have elongated elliptical orbits get close to the sunand then out into the further reaches of the Solar System

Classified according to the length of their orbital periods: the longer the period the longer the ellipse

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Short-period comets less than 200 years, orbit in the ecliptic plane, same direction as the planets

Long-period comets have highly eccentric orbits and periods ranges from hundreds to millions of years

Single-apparition comets similar to long-period comets, but have parabolic or slightly hyperbolic trajectories

Oribital Periods

Orbits range from a few years to thousands of years

Short period comets are from Kuiper belt

Long period comets are from Oort Cloud due to gravitation

Comet Halley

Seen from Earth every 75 years

Short period comet

gravitational pull of the major planets alters the

orbital period from revolution to revolution.

nucleus is around 16x8x8 kilometers

ORIGIN OF WATER

One theory of where water came from is that comets from space brought water to earth

This theory is plausible because one of the components of comets is ice

Interesting facts Many scientists believe that comets brought the

vast quantities of water that now fill the Earth's oceans

July 1994 when Comet Shoemaker-Levy 9 broke up into pieces and collided with Jupiter

video

http://www.youtube.com/watch?v=iHeklbuyBSs