Origin of Asteroids

Asteroids are believed to have originated during the formation of the Solar System, when planetesimals accreted from solar nebula. The more primitive carbonaceous asteroids may have evolved little since then, while the other types may have been parts of larger bodies that first accreted and later broke up by collisions.

Recently a few small asteroids have been discovered in highly elliptical orbits that come inside the orbit of Mars, some crossing the orbit of the Earth - the Apollo, Amor, and Aten families.

                                          

Known Asteroids

Today a large number of asteroids are known.Around two thousand of them have well-determined orbits and revolve around the Sun as part of the 'main belt', in the gap between Mars and Jupiter.

They are tiny, only a handful having a diameter of more than a few tens of kilometres, and the combined mass of all the asteroids is thought to be only a fraction of that of the Moon.

Asteroids

Asteroids are the debris of planets that orbit the Sun. These are different sized chunks of rock,ranging from specks of dust to some which are a few hundred kilometres across.

Asteroids follow different orbits.In the eighteenth century, astronomers were convinced that a missing world existed between Mars and Jupiter.A search was mounted and the first asteroid, Ceres, was discovered in 1801.

Meteors and Meteorites

Meteors are the hot glowing pieces of rocks and dust from space that plunge into the Earth's atmosphere.Most meteors burn up above an altitude of 100km. If u gaze at the stars for half an hour on a clear bight,you will seen an occasional streak of light, which is a meteor's glowing trail.

Orbits of comets

 Orbits of comets

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Comets are believed to be left over particles from beginning of the Solar System,when most of these particles collided with each other to build up the planets. The comet nuclei, containing crumbly rock particles trapped in frozen ice, were left. If their orbits take them near the Sun, the heat turns the outer ice to vapour and solid particles are released as dust. In their frozen state far from the Sun, comets are invisible. Each time a comet passes near the Sun it pours some more of its nucleus into space. Eventually it 'dies' and becomes just an orbiting rock.  

Halley's Comet

Halley's Comet's

Halley's comet is the most famous of all comets, recorded by Chinese astronomers in 467 BC (and possibly in 611 BC). It is a periodic comet orbiting the Sun in a retrograde direction with a period of 76 years. It is named for the English astronomer Edmund Halley, who applied to comets Newton's theory of planetary motions and correctly predicted the return of the bright comet in the year 1758.

Comets

Comets

Comets are icy objects which travel through the Solar System. A bright comet in the night sky looks like a hazy patch with a long wispy tail. Comets travel in orbits through the Solar System.They evaporate gas and dust and grow long tails when they are near enough to the Sun's heat and light.

The tails always point away from the Sun, blown by the light and streams of atomic particles from the Sun. the most famous comet, Halley's Comets, can be seen from the Earth every 76 years.