Get premium membership and access revision papers with marking schemes, video lessons and live classes.
  OR
Processing. Please wait.

 Form 1 Geography lessons on the earth and the solar system

Theories explaining the origin of the solar system

 (8m 3s)
1695 Views     SHARE

Download as pdf file

Answer Text:
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
Theories
A theory is a set of reasoned ideas intended to explain facts or events
1. 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 Weaknesses
• Doesn’t explain the origin of the sun and star.
• Minimal chance of a star approaching another
• Materials would disperse than condense
2. 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.
3. Nebula Cloud Theory
• There was a slowly rotating cloud of dust and gas called Nebula
• It cooled and began to contract
• 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 Evidence
• Rotation and revolution of planets in anticlockwise direction Weakness
The origin of nebular is not explained.
4. 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.
Weaknesses
• Doesn’t explain the origin of the star
• Doesn’t explain the cause of explosion


|