Grade 7- The Solar System

Solar system is the group of heavenly bodies comprising the sun and the planets.

The origin of the solar system

The 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

The Nebula Cloud Theory

• There was a slowly rotating cloud of dust and gas called Nebula. This caused high concentration of materials at the centre that formed the sun.

• Rotation speed increased and successive rings of gaseous materials were formed.

• The rings condensed to form planets.

• The materials grew in size enough to exert their own gravitational pull.

• The central gaseous material remained as the sun

Mercury

1. Nearest from the sun

2. Its 58m km from the sun

3. Has no satellites

4. Takes approximately 88 earth days to revolve around the sun

Venus

1. 2nd planet from the sun

2. It’s 108m km from the sun

3. One of the brightest planets

4. Can be seen clearly with naked eyes

5. Takes approximately 225 earth days to revolve around the sun

6. Slightly smaller than the earth

7. Has no satellites

8. Together with the earth they are called twin planets due to having many similarities

Mars

1. Also called The Red Planet because when it’s observed through a telescope it appears reddish.

2. The 4th from the sun

3. Slightly smaller than the earth

4. Approximately 228m km from the sun

5. Takes 687 earth days to revolve around the sun

6. Between Mass and Jupiter there are small celestial bodies called planetoids.

7. Has no satellite.

Jupiter

1. 5th planet from the sun

2. Approximately 778m km from the sun

3. Largest in the universe

4. Rotates on its own axis at very fast speed

5. Has flattened poles due to its fast speed of rotation

6. Has very thick layers of ice on its surface

7. Takes 12 earth years to revolve around the sun

8. Has 16 satellites

Saturn

1. 6th planet from the sun

2. Second largest planet

3. Approximately 1427m km from the sun

4. Takes 29 ½ earth years to revolve around the sun

5. Has a ring around it

6. Has 18 satellites

Uranus

1. 7th planet from the sun

2. About 4 times bigger than the earth

3. Approximately 2870m km from the sun

4. Also rotates very fast

5. Also has flattened poles due to fast speed of rotation

6. It appears greenish foe being surrounded by methane gas

7. Has 8 satellites

8. Takes 84 earth years to revolve around the sun

Neptune

1. One of the farthest from the sun

2. 8th planet from the sun

3. Approximately 4497m km from the sun

4. Has 8 satellites

5. Takes 165 earth years to revolve around the sun

6. Very similar in size, colour and character with Uranus.