New Words : 1. Solar : Related to the sun. 2. Telescope : A scientific equipment which is used for seeing distant objects such as stars and planets. 3. Farthest : At the longest distance. 4. Tilted : A position in which one side of something is higher than the other. 5. Hemisphere : One of the halves of the earth. 6. Stars : Fixed heavenly bodies having their own heat and light. 7. Planets : Moving heavenly bodies which have no heat or light of their own. 8. Axis : An imaginary line running from the North Pole to the South Pole of the earth. 9. Orbit : The fixed path in which planets revolve round the sun. 10. Equator : An imaginary line that divides the earth into two equal halves.
Remember These Points -
+ A star is a huge ball of burning gases. + A planet is a huge ball of rocks and gases. Earth is the only planet which has life on it. + The sun, the nine planets, their moons, etc. form the solar system. + The sun is at the centre of the solar system. + Pluto is no longer considered a planet. + The revolution of the earth causes seasons and the rotation of the earth causes day and night. + Moon is the only natural satellite of the earth. Stars have their own heat and light.
Answer the following questions :
1. What do you mean by the solar system?
The Sun and all heavenly bodies moving around it are together called the solar system.
2. Why is the earth called the 'blue planet'?
The earth is called the ‘blue planet' because earth looks blue from space due to the presence of water.
3. What is rotation and revolution?
Rotation - The movement of the earth on its axis is called rotation. Revolution- Our earth moves round the sun in an elliptical orbit. This movement of the earth is called revolution,
4. How are day and night caused?
The rotation of the earth causes day and night. During rotation, the half of the earth that faces the sun experiences day time. On the other hand, the part of the earth which does not face the sun experiences night.
5. How are seasons caused?
The revolution of the earth round the sun causes different seasons. When the North Pole is tilted towards the sun, the northern hemisphere gets more sunlight. It has the summer season. At the same time, the South Pole is tilted away from the sun. So, the southern hemisphere has winter season. Almost six months later the situation is the reverse and the half which had summer, now has winter and the half which had winter, now has summer.
6. Give two reasons why earth is the only planet having life on it.
i) Water is present on the earth in its three states- solid (ice), liquid (water), gas (water vapour). ii) The oxygen gas which supports life is found on the earth.
7. What are constellations? Give an example.
Groups of stars making beautiful patterns are called Constellations. Ex- Ursa major, Ursa minor, Orion, Scorpius.
8. Write two differences between a star and a planet.
i) Stars are the glowing balls of gases.
i) Planets are the mixture of gases and rocks.
ii) Stars have their Own light and heat.
ii) Planets do not have their own light and heat.
Answer in one word-
1. The only planet with many kinds of Living things - Earth 2. A planet which has rings around it. Saturn 3. The red planet - Mars 4. The planet closest to the sun - Mercury 5. The smallest planet - Mercury
Tick (✔) the correct answer:
1. The earth is tilted on its axis at an angle of (a) 32.5° (b) 23.5° [✓] (c) 2.35° 2. Rotation means (a) making another object move round itself (b) going round another object (c) spinning on own axis [✓] 3. The earth is called the 'blue planet' because (a) it revolves round the sun (b) it has water on it [✓] (c) it lies between Mars and Venus 4. The moon (a) has plenty of water (b) has air (c) has no light of its own and reflects the sun's light [✓] 5. A group of stars making a beautiful pattern is called (a) milky way (b) constellation [✓] (c) solar system