some important definitions

[alihashmatkhoso]

Asteroids

Basically the word asteroid means (Star like) these are small, irregularly shaped rocky objects, which orbit the sun between the orbits of Mars and Jupiter.

• Asteroids are also known as small planets and planetoids
• Ceres asteroid was the first to be discovered in 1801 and is the largest asteroid
• Combination of 16 asteroids having 240km diameter
• Some of asteroid may collide with earth




Meteorites

Meteorites are small chunks of iron and rock, formed to be resulted from the collisions between asteroids or disintegration into fragments of comets.

• Meteorites inter into earth surface and become a meteor

• A meteor is falling star that is usually seen at the night time

• Most of the meteor burn up before the reach on the earth surface

• If the do reach on the earth ground they become meteorites

• Meteorites can be seen at the distance of 70 km from earth

• Meteorites are heavy bodies having weight about 60 tons

Comets

Comets are those bodies which revolve around the sun, they are mainly composed of ice and dust most comets have three parts which are as under

1. A solid center

2. a head or round comma, that surrounds the center and consist on dust particles mixed with frozen water, frozen methane and frozen ammonia


3. a long tail of dust and gases that escape from the head
Other characteristics of comets
• most comets stay near the solar system

• comet are usually about 10km or 6 miles across

• millions of comets are present in solar system

• Halley’s comets is the famous example


Halley’s Comet

Halley’s Comet is named after the British astronomer Edmund Halley who calculated its orbit in 1705.

• The Halley’s comet visits the sun every 76 years

• It last visited the sun in 1986, but it passed very far from the earth

• It is predicted it will return in the year 2062