Geography
Posted in Geography

EXTERNAL STRUCTURE OF THE EARTH

383 ViewsEXTERNAL STRUCTURE OF THE EARTH   a) The Atmosphere Layer of gases surrounding the earth. The earth revolves with it…

Geography
Posted in Geography

THE STRUCTURE OF THE EARTH (Internal Structure)

387 ViewsTHE STRUCTURE OF THE EARTH (Internal Structure) Internal Structure of the Earth The evidence used to study the earth’s…

Geography
Posted in Geography

REVOLUTION OF THE EARTH

217 ViewsREVOLUTION OF THE EARTH Movement of the earth in its orbit around the sun. It’s in anticlockwise direction. The…

Geography
Posted in Geography

THE ORIGIN OF THE EARTH

238 ViewsTHE ORIGIN OF THE EARTH A star with a greater gravitational pull passed near the sun It attracted large…

Posted in Geography

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

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
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

Evidence

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.

Weaknesses

Doesn’t explain the origin of the star

• Doesn’t explain the cause of explosion