Solar system is the description of the position of the earth and other planets in relation to the sun. The solar system comprises of the sun and the nine planets. All the planets revolve round the sun in “elliptical orbits”.
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The Universe
The universe is made up of many heavenly bodies, group of stars form clusters which are known as galaxies or nebulas. Our local groups or galaxy i.e the earth galaxy is known as ‘The Milky Way’. It contains twenty seven galaxies.
A satellite is a smaller body which moves round a planet. The moon is the natural satellite of the earth.
Below is a summary of the components of the Solar System
| Planets | Number of satellites | Distance from sun in Km | Years it takes to complete revolution |
| Mercury | None | 57,600,000 | 88 days |
| Venus | None | 107,200,000 | 225 days |
| Earth | One | 148,800,000 | 365 days |
| Mars | Two | 227,200,000 | 687 days |
| Jupiter | Twelve | 772,800,000 | 11.9 years |
| Saturn | Nine | 1,417,600,000 | 29.5 years |
| Uranus | Five | 2,854,400,000 | 84 years |
| Neptune | Two | 4,468,800,000 | 164.8 years |
| Pluto | None | 5,850,000,000 | 247.7 years |
EVALUATION QUESTIONS:
- What is a solar system?
- What are Galaxy, Satellite and Orbit?
OTHER IMPORTANT SPECIFICATIONS OF THE NINE PLANETS
MERCURY
- This is the smallest planet.
- It is the closest planet to the sun.
- It is the hottest planet being the closest to the sun.
- It contains no living thing because of its high temperature.
- It has the shortest orbit round the sun.
VENUS
- This is the second closest planet to the sun.
- It contains no living thing.
- It is often referred to as THE EARTH TWIN because of their close proximity in size, mass and density.
EARTH
- This is the only planet where life exists. This is because earth is the only planet that contains oxygen, and force of gravity.
- It has one natural satellite known as Moon.
MARS
- This planet is believed to have the possibility of supporting some plant’s life.
- It has two satellites.
JUPITER
- This is the largest planet in the solar system.
- Its surface contains gases such as hydrogen and methane with light and dark bands.
SATURN
- This is the second largest planet after Jupiter.
- It has three rings around it.
URANUS
- This is the only planet that revolves round the sun in a clockwise direction.
- It takes Uranus 84 years to complete its orbit.
NEPTUNE
- This planet is very cold because of its distance from the Sun.
- It has two satellites
PLUTO
- This is the farthest planet from the sun.
- It is the coldest planet.
- It has the longest orbit round the sun
EVALUATION QUESTIONS
- Describe the universe.
- Give at least one characteristic of each of the planets.
GENERAL EVALUATION QUESTIONS
- What is a solar system?
- Name the first four planets and describe their characteristics.
- State the characteristics of the last planet.
- What is a satellite?
- Mention the satellite of the earth.
WEEKEND ASSIGNMENT
- Which of the following statement is not true of the solar system? (a) The rays of the sun gives energy of the system (b) All the planets rotate around the sun (c) The planets revolve around the sun.
- Which two planets lie between the sun and the earth? (a) Venus and Mars (b) Venus and Jupiter (c) Mercury and Venus
- The planet with the largest orbit around the sun is (a) the Earth (b) Pluto (c) Jupiter
- Which of the following planet has no satellite? (a) Venus (b) Uranus (c) Neptune
- The planet often considered as the earth’s twin because of their close similarity in size, mass and density is (a) Venus (b) Saturn (c) Mercury
THEORY
- What is solar system? List the 9 planets in order of their distance from the sun.
- State three characteristics of the planet Earth.
See also