Class Notes NCERT Solutions for CBSE Students
Question: On the Earth, the Sun rises in the east and sets in the west. Will it be the same on Venus?
Answer: Unlike the earth and most other planets, Venus rotates on its axis from east to west, i.e. in the opposite direction. Hence on Venus the sun will rise in the west and set in the east.
Question: Answer the following, giving reasons. a. Can you light a fire on the Moon? b. If a meteor falls on the Moon, can you hear it fall? c. Can you see the meteor falling on the Moon? Can life exist on the Moon?
Ans: Reasons are as follows:
(a) We cannot light a fire on the moon as there is no atmosphere on the moon.
(b) If a meteor falls on the moon, we cannot hear it fall as there is no air. Sound needs a medium to travel.
(c) Yes, we can see the meteor falling on the moon.
(d) Life cannot exist on the moon because there is no air, i.e. no oxygen.
Question: If the planet Saturn is inserted in water, will it float or sink? Why?
Answer: The planet Saturn will float because its density is less than that of water.
Question: What do you mean by celestial objects?
Answer: Any naturally occurring object in the observable universe is called a celestial body. Stars, planets, satellites, comets, etc. are examples of celestial objects.
Question: What are comets?
Answer: A comet is a celestial body which revolves around the sun in a highly elliptical path.
Question: What is a meteor?
Answer: When a small object from the space reaches the atmosphere of the earth; it enters at a very high speed. The high speed creates so much friction that the object burns off before reaching the earth. Such objects are called meteors.
Question: Write a short note on Pole Star.
Answer: While other stars appear to move with gradual progress of night, the pole star remains fixed at its position. This happens because the pole star is in line with the axis of the earth. The pole star appears in the northern sky. It is only visible from the northern hemisphere. However, the fixed position of the pole star has helped humans since ages.
