NCERT Textbook Solutions and other Questions and Answers
Q1: Answer the following questions briefly.
(a) How does a planet differ from a star?
- Stars emit their own light and heat. While planets do not have their own light.
- There are millions of stars while there are eight planets in our solar system.
- Usually stars twinkle at night while planets glow without any flickering.
The sun, eight planets, satellites and some other celestial bodies known as asteroids and meteoroids form the solar system.The sun is in the centre of the solar system. All the planets of the solar system move around the sun in fixed paths.
(c) Name all the planets according to their distance from the sun.
Answer: Mercury, Venus, Earth.Mars, Jupiter, Saturn, Uranus, Neptune
(d) Why is the Earth called a unique planet?
Following are the reasons the Earth is considered as a unique planet:
- The land, water, air and the favourable climate facilitate the origin of life and help them in their development on the Earth.
- The earth is neither too hot nor too cold.
- The air has life-supporting gases like oxygen.
- No other planet of the solar family has life like that of the Earth.
(e) Why do we see only one side of the moon always?
The moon moves around the earth in about 27 days. It takes exactly the same time to complete one spin. As a result, only one side of the moon is visible to us on the earth.
(f) What is the Universe ?
Answer: A universe consists of millions of galaxies (such as Milky way). It is vast and ever expanding. Space scientists speculate that the Universe had its origin some 15,000 million years ago.
Q2. Tick the correct answer.
(a) The planet known as the “Earth’s Twin” is(i) Jupiter
Answer: (iii) Venus
(b) Which is the third nearest planet to the sun ?(i) Venus
Answer: (ii) Earth
(c) All the planets move around the sun in a(i) Circular path
(ii) Rectangular path
(iii) Elongated elliptical path
Answer:(iii) Elongated elliptical path.
(d) The Pole Star indicates the direction to the(i) South
Answer: (ii) North
(e) Asteroids are found between the orbits of(i) Saturn and Jupiter
(ii) Mars and Jupiter
(iii) The Earth and Mars
Answer:(ii) Mars and Jupiter
3. Fill in the blanks.
(a) A group of _stars__ forming various patterns is called a _constellation_.
(b) A huge system of stars is called_galaxy_.
(c) _The Moon__is the closest celestial body to our earth.
(d) _The Earth_is the third nearest planet to the sun.
(e) Planets do not have their own__light__ and _heat_.
Choose the correct answer
4. The stars are not visible during the day becausea) of their size
b) of their self illumination
c) of their distance
d) of Sun’s brightness
Answer: d) of Sun's brightness
5. Which of the following is a natural satellite?
Answer: a) moon.
6. Name the nearest star to the Earth.
7. Name the nearest star to the Earth after the sun.
Answer: Proxima Centauri
8. Why the earth is called blue planet?
Answer: From the outer space, the earth appears blue because its two-thirds surface is covered by water. It is, therefore, called a blue planet.
9. How much time does it take to light of the sun reach the earth?
Answer: About eight minutes.
10. Name the first person who stepped on the surface of the moon.
Answer: Neil Armstrong