Stars and the solar system Worksheet-13

Stars and the solar system Worksheet-13

1. Explain the structure of the moon.

2. Draw the diagram of Orion and explain it.

3. How can you locate the star-Sirius?

4. (a) Name the natural satellite of the Earth,

(b) In how many days this satellite completes one revolution around the Earth?

(c) In how many days this satellite revolves around its own axis?

5. (a) Name the star nearest to the Earth (except Sun).

(b) How much time does the light from this star take to reach the Earth?

(c) Name the gas found in stars.

6. Explain how artificial satellites help in transmission of television programmes over large areas.

7. Give reasons why life is possible only on earth.

8. Name the Jovian Planets. Give their general characteristics.

9. (a) Why does the sun appear brighter and hotter than other stars ?

(b) How much time is required for light to reach the Earth from the sun ?

(c) Give the composition of the sun.

(d) What is the source of energy of the sun ?

10. Compare the solar system with the structure of atom.

11. (a) What is meant by revolution of Earth?

(b) What is meant by rotation of Earth?

(c) What is the direction of rotation of Earth?

(d) How much time is required for rotation of Earth?

(e) How much time is required for one revolution of Earth?

12. Name some artificial satellites.

Answer:

1. The moon's surface is dusty and barren and has craters of different sizes. It also has a large number of steep and high mountains.

2. Orion is a winter constellation having seven or eight bright stars. It is also called the hunter as the three middle stars represent the belt of the hunter. The four bright stars appear to be arranged in the form of a quadrilateral.

3. The star-Sirius is the brightest star in the sky and is located close to Orion. Imagine a straight line passing through the three middle stars. Look along this line towards east. This line will lead you to the Sirius.

4. (a) Moon is the natural satellite of the Earth.

(b) The Moon takes 27(1/3) days to revolve around the Earth.

(c) The Moon takes 27(1/3) days to spin on its own axis.

5. (a) Proxima Centuari is the star nearest to Earth except Sun.

(b) It's light takes 4.5 years to reach the Earth.

(c) Hydrogen gas is present in the star.

6. The picture and sound to be transmitted is first converted into electrical signals. These electrical signals are then converted into a special type of waves and transmitted in air from a transmitting antenna.

The waves travel in all directions and some of them reach the artificial satellites. The artificial satellites have special instruments which receive the signals transmitted by the Earth station. The signals so received are then amplified and retransmitted, by the instruments fit on the satellite Antennas fixed in a number of stations on Earth receive the signals transmitted from the satellite and finally reach the television at home.

7. Earth is the only planet having life because

(i) It is situated just at the right distance from the sun.

(ii) It has the correct temperature for living organisms.

(iii) Presence of water on earth,

(iv) Suitable atmosphere around the earth.

(v) It has a blanket of ozone.

8. Jupiter, Saturn, Uranus and Neptune are known as Jovian planets. Their general characteristics are —

(i) They are mainly gaseous.

(ii) Mass and size of the outer planets are very large.

(iii) They have a ring system around them.

(iv) They have a large number of moons.

9. (a) The Sun appears brighter and hotter than other stars because it is nearest to the Earth as compared to other stars.

(b) The light from the Sun reaches the Earth in 8 minutes and 20 seconds.

(c) The Sun consists of 70% hydrogen gas, 28% helium gas and 2% of heavier elements such as carbon, nitrogen, oxygen, etc.

(d) In the Sun nuclear fusion of hydrogen to helium, with the release of large amount of energy takes place.

10. Similarities Differences

(i) In an atom, the protons and neutrons are tightly packed in the nucleus and electrons revolve around it in fixed orbits.

(ii) In the solar system, the Sun is in the centre and the planets revolve around it in fixed orbits. (i) In an atom, the electrons can jump from one orbit to another

(ii) In the solar system, the planets remain in their orbits. They cannot change their orbits.

11. (a) The motion of the Earth around the sun is called revolution.

(b) The spinning of the Earth about its own axis is called rotation of the Earth.

(c) The earth spins from west to east.

(d) One complete rotation of the Earth takes 24 hours.

(e) One complete revolution of the Earth takes 365^1/4 days.

12. Some artificial satellites are Bhaskar, Aryabhatta, Rohini, Insat IA, IB and IC series.