STARS AND THE SOLAR SYSTEM CBSE Class 8 Important Question Solutions

Short Answers

Q.1.Name the planet appears I the northern sky before sun rise?

Ans: Venus brightest of all planets

Q.2. Name the planet which has 28 moons?

Ans: Jupiter manly consist of hydrogen and helium gases

Q.3. In which direction stars move except Polar star?

Ans: When seen from earth stars appears to move from east to west.

Q.4. Why pole star appears stationary?

Ans: As it lies on the imaginary axis of the rotation of the earth.

Q.5.Which two planets have asteroids between them?

Ans: asteroids are the rocks pieces that revolve around the sun between the orbit of Mars and Jupiter.

Q.6. Which comet visit the earth after 76 year?

Ans: Halley’s comet. Heavenly bodies that revolve around the sun and appears as bright as glowing ball with a long tail is called comet.

Q.7.What happen to meteors when enters the earth’s atmosphere?

Ans: meteors when enters the earth’s atmosphere starts glowing and are seen as a bright steak of light fleshing momentarily across the sky.

Q.8.What is the high tog geostationary satellite from the earth surface?

Ans: 36000km and used for satellite communicacation.

Q.9. What does term INSAT mean?

Ans: Indian National Satellite.

Q.10.Name the first Indian satellite launched success fully.

Ans : Aryabhata on 19 april,1975

Q.11. Some stars are bright and some are dim; some stars look white while some may look blue and some red. why?

Answer: Stars differ in apparent brightness for two reasons; one is that they are at different distances and the other is that they differ in their intrinsic (actual) brightness

One Word Answers

Q.1.Name the planet appears to the northern sky before sun rise?

Ans: Venus brightest of all planets

Q.2. Name the planet which has 28 moons?

Ans: Jupiter manly consist of hydrogen and helium gases

Q.3. In which direction stars move except Polar star?

Ans: When seen from earth stars appear to move from east to west.

Q.4. Why pole star appears stationary?

Ans: As it lies on the imaginary axis of the rotation of the earth.

Q.5.Which two planets have asteroids between them?

Ans: asteroids are the rocks pieces that revolve around the sun between the orbit of Mars and Jupiter.

Q.6. Which comet visit the earth after 76 year?

Ans: Halley’s comet. Heavenly bodies that revolve around the sun and appears as bright as glowing ball with a long tail is called comet.

Q.7.What happen to meteors when enters the earth’s atmosphere?

Ans: meteors when enters the earth’s atmosphere starts glowing and are seen as a bright steak of light fleshing momentarily across the sky.

Q.8.What is the high tog geostationary satellite from the earth surface?

Ans: 36000km and used for satellite communicacation.

Q.9. what does term INSAT mean?

Ans: Indian National Satellite.

Q.10.Name the first Indian satellite launched success fully.

Ans: Aryabhata on 19 april,1975

11.  What is the vast space which includes everything around us called?

Ans: Universe

12. Name the various objects that constitute the universe?

Ans: All the stars, the sun, the planet and their moon, meteorites, comets.

13. What is the distance travelled by light in one year called?

Ans: One light year=9460 billion kilometer

14. How much time sunlight takes to reach the earth?

Ans: 8.3 sec.

15. What material the stars are made up of?

Ans: Hydrogen gas

16. Name the celestial bodies you see in night sky?

Ans: stars

17. Why celestial bodies appear to move from east to west in the sky?

Ans: This is because the earth rotates from west to east.

18. Name the stars which appear stationary when sea from earth?

Ans: The pole star or Druvtara

19. Name the galaxy we belong to?

Ans: milky Way (Akash Ganga)

20. What is the most distinguish Feature of Jupiter?

Ans: Great red spot. It is believed to be a storm in its atmosphere.



 Long Answers

1.Why is Venus the hottest planet even though Mercury is closest to the Sun?

Ans: Venus is a very hot planet (about 480 °C), even hotter than Mercury, though it is further away from the sun. This is because of the high percentage of carbon dioxide in its atmosphere, which causes heating due to the greenhouse effect

2.How is an artificial satellite different from a natural satellite? Give one example of each.

Ans: A celestial obj ect that revolves around a planet is known as a natural satellite or moon of the planet. Example: The moon is the natural satellite of the earth. Whereas artificial satellites are man - made machines which are sent from the earth to get help in communication , weather forecasting, etc. Examples: Aryabhata, Bhaskara, Rohini, INSAT - 1B, APPLE, etc.

3. What major factors have enabled life to evolve and survive on the Earth?

Ans: All the factors necessary for life are present only on Earth. It has an atmosphere containing the gases, oxygen and carbon dioxide, which are necessary for

life. (ii) It has water in liquid form, which is essential for life.

(iii) Being at the right distance from the sun, it is not as hot as Mercury or Venus, nor is it as cold as the planets which are further away.

4.Give five ways in which artificial sate llites are useful to us.

Ans: Artificial satellites are very useful to us.

(i) They help in television and radio transmission.

(ii) They help in telephone communication.

(iii) They help us to study and forecast the weather by sending cloud pictures to the earth, taken from space.

(iv) They help in locating minerals.

(v) They help in studying agricultural yield on the earth by photographing from above.



5.What do you mean by 'phases of the Moon'? Draw a labelled diagram to show the phases of the Moon.

Ans: The moon's revolution and rotation are such that only one side of the moon always faces us. Also, we can see that portion of this side which reflects sunlight to us. This changes every day as the relative positions of the sun, earth and moon change every day. These are explained here. New moon: When we do not see the moon at all Crescent moon: We see only a part of the moon First quarter: When we see half of the moon Gibbous moon: When we see more than half of the moon Full moon: When we see the full moon. Then the cycle reverses. These shapes of the bright part of the moon, as seen from the earth, are known as phases of the moon.

6. Both galaxies and constellations are groups of stars. Give two differences between them.

Ans: (i) A group of billions of stars make up a galaxy. Whereas a small group of stars that appear to form an imaginary pattern when viewed from the earth is known as constellation.

(ii) Our solar system is in the galaxy calle d the Milky Way whereas some important constellations are Ursa Major, Ursa Minor, Orion, Cassiopeia, etc

7.What is comet? How is its tail formed?

Ans: Comet is small body of ice and dust revolving around the sun in its elongated orbit. When comet approaches the sun, it heats up and leaves behind a stream of hot glowing gases and dust particles. We see it as a tail

8.Write a short note on constellation.

Answer: Many a time, a group of stars as seen from the earth, appears to form some kind of pattern. Our ancestors imagined some known shapes formed by many groups of stars and gave them specific names. Such a group of stars is known as a constellation. Some easily identifiable constellations are Ursa Major or Vrihat Saptarshi, Ursa Minor or Laghu Saptarshi and Orion or Mriga

9.What is the difference between meteors and meteorites?

Ans: Meteors ar e small objects made up mainly of stones present in space. They regularly enter the earth's atmosphere. As a meteor enters the earth's atmosphere at high speed, it is heated by friction with air, and in most cases it burns to ashes in a very short time. If a meteor is large, it may fall on the earth's surface before being completely burnt out. Such meteors are called meteorites

10.Why was it necessary to define a new unit to measure distances in the universe? What is this unit?

Ans: The distances between heavenly bodies in space are very, very large. Measuring these distances in kilometres would mean dealing with very large numbers. Astronomers, therefore, use special units to measure distances in space. Instead of a kilometre, they use a unit called light year. A light year is the distance that light travels in one year

11.Which property of the Pole Star makes it very useful for sailors?

Ans: Sailors used the Pole Star to fin d the north direction because it is the only star that remains stationary in the sky with respect to the earth.

HOTS QUESTIONS: Think and answer.

1. Why can't we see stars during the day?

Ans: Due to the brightness of the sun during the day we cannot see stars at that time.

2. Suppose a star which is 100 light years away explodes today. It is highly unlikely that you will be able to see the explosi on. Why?

Ans: It is highly unlikely that a person alive today lives to see the exploding star as light from the star will take 100 years to reach the earth.

3. On the Earth, the Sun rises in the east and sets in the west. Will it be the same on Venus? Ans: 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.

4. Since your birth, how many times have you gone around the Sun ?

Ans: As many times as my age in years.

5. 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: (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.

6. If the planet Saturn is inserted in water, will it float or sink? Why?

Ans: The planet Saturn will float because its density is less than that of water