*Comets Are celestial objects made of ice and

dust that revolve around the sun in long, elliptical orbits.

Edmond Halley an English astronomer, was on of the

first men to recognize that comets are definitely members of the solar sysytem.

*Three orbits:

1. It may make one loop around the sun and return to the outer shell.

2. It can fall into a new, eccentric orbit around the sun.

3. It may approach so close to the sun that it disintegrates.

*Several distinct parts:Nucleous- A head has a solid core, surrounded

by these materials.Coma- The head of a comet, believed to be

composed of frozen gases and ice mixed with smaller quantities of meteoric materials.

Hydrogen cloud- huge (million of km in diameter) but very sparse envelope of neutral hydrogen.

Dust tail- up to 100 million km long, composed of smoke and dust particles driven off the nucleus by escaping gases; the most prominent part of a comet.

Plasma tail- up to 100 million km long, composed of plasma and laced with rays and steamers caused by interactions with the solar winds.

*AsteroidOr planetoids are small bodies observed to

range in diameter from a kilometre to a thousand kilometres.

*Ceres- largest asteriod.The first to be discovered.

Hermes- A small asteroid, barely more that a mile in diameter, has come within 485,000 miles of the Earth.

Origin of Asteroid1. Some astronomer believe that they are fragments

of a planet which was shattered by gravitational forces when it passed too close to the giant Jupiter.

2. Other suggest that the asteroids may be the pieces of two planets which collided and were both blasted into fragments.

3. A completely different into theory is that they are fragments of the solar system which never grew large enough to form an ordinary planet.

*Meteoroid-Small solid particles from a comet or asteroid.

*Meteorites- The remains of the meteoroids found on the surface of the Earth.

*Meteors- When these particles become visible in the atmosphere.

Given to these small visitors, comes from a Greek word meaning “something in the air”.

Shooting Stars- Streaks of light that last few seconds in the sky.

The meteors that reach the Earth seem to come from two different sources:

1. Small fragments like those in the belt of asteroids between Mars and Jupiter.

2. Appears to be the tails of comets.

“Twinkle, twinkle little star, how I wonder what you are, Up above the world so high, like a diamond in the sky”…

Star- gigantic balls of flaming gases.

*Blue or White star- The hottest star.

*Yellow star- The sun, the hotter star.

*Red stars- coolers or least hot.

*Constellation groups of star.

When the sun moves against the background of constellations it is called zodiac constellations.

13 Zodiac constellations1. Capricorn

2. Aquarius

3. Pisces

4. Aries

5. Taurus

6. Gemini

7. Cancer

8. Leo

9. Virgo

10.Libra

11.Scorpio

12.Saggitarius

13.Ophiuchus

*Galaxies- are huge systems of billions of stars and other celestial bodies.

*Milky way- the Galaxy which our sun belong.