Unit-1

1. The big bang theory

1.1. 1. The Universe was created 13 700 years ago by a big explosion.

1.2. 2. Following the big explosion the matter cooled down and formed helium and hydrogen. The other elements came from this two

1.3. 3. The universe has been expanding since the Big Bang.

2. The life Cycle of a star

2.1. Medium or small star

2.1.1. 1. Stellar nebula

2.1.2. 2. Star

2.1.3. 3. Planetary nebula

2.1.4. 4. White dwarf

2.2. Massive star

2.2.1. 1. Stellar nebula

2.2.2. 2. Massive star

2.2.3. 3. Supernova

3. Movements of planets and dwarf planets

3.1. Rotation

3.2. Revolution

4. Other celestial bodies

4.1. Asteroid

4.2. Satellites

4.3. Comet

4.4. Meteroid

5. A historical view of the Earth’s position

5.1. Geocentric model

5.2. Heliocentric model

6. Galaxy are big groups of stars,gases,planet and other celestial bodies held together by gravity

6.1. Eliptical Galaxy

6.2. Barred Spiral Galaxy

6.3. Spiral Galxy

6.4. Irregular galaxie

7. Solar system was created 4 600 millions years ago

8. Dwarf planets

8.1. Ceres

8.2. Eris

8.3. Pluto

9. Planets

9.1. Mercury

9.2. Venus

9.3. Earth

9.4. Mars

9.5. Jupiter

9.6. Saturn

9.7. Uranus

9.8. Neptune