THE EARTH AND THE SOLAR SYSTEM
Solar system is the group of heavenly bodies comprising the sun and the nine planets.
The origin of the Solar System
A theory is a set of reasoned ideas intended to explain facts or events
- Passing Star Theory
- A star with a greater gravitational pull passed near the sun
- It attracted large quantities of gaseous materials from the sun
- The materials split, cooled and condensed to form planets
- The planets were set in orbit by the passing star
- Doesn’t explain the origin of the sun and star.
- Minimal chance of a star approaching another
- Materials would disperse than condense
- Collision Theory
- Star with greater gravitational pull passed near the sun
- It attracted large quantities of gaseous materials
- The materials split into portions
- Large portions collided with smaller ones and swept them to form planets.
The weaknesses are the same as the passing star’s Theory.
- Nebula Clod Theory
- There was a slowly rotating cloud of dust and gas called Nebula
- It cooled and began to contact
- Rotation speed increased and successive rings of gaseous materials were formed.
- The rings condensed to form planets
- The central gaseous material remained as the sun
- Rotation and revolution of planets in anticlockwise direction Weakness
The origin of nebular is not explained.
- Supernova/explosion Theory
- There was a violent explosion of a star.
- A cloud of dust (nebular) remained from the star.
- There was fast movement of the cloud due to the force of explosion.
- Rotation speed increased due to gravitational attraction
- The cloud flattened into a disc.
- The matter began to accumulate towards the centre to form a proto-sun which later began to shine.
- The rest of the cloud collapsed to form planets.
- Doesn’t explain the origin of the star
• Doesn’t explain the cause of explosion