Stars and Solar System
NCERT Solution
Question 1: Which of the following is NOT a member of the solar system?
- An asteroid
- A Satellite
- A Constellation
- A Comet
Answer: (c) A Constellation
Question 2: Which of the following is NOT a planet of the sun?
- Sirius
- Mercury
- Saturn
- Earth
Answer: (a) Sirius
Question 3: Phases of the moon occur because
- We can see only that part of the moon which reflects light towards us.
- Our distance from the moon keeps changing.
- The shadow of the Earth covers only a part of moon’s surface.
- The thickness of the moon’s atmosphere is not constant.
Answer: (a) We can see only that part of the moon which reflects light towards us
Question 4: Fill in the blanks:
- The planet which is farthest from the Sun is ____________ .
- The planet which appears reddish in colour is ____________ .
- A group of stars that appear to form a pattern in the sky is known as a ____________ .
- A celestial body that revolves around a planet is known as __________.
- Shooting stars are actually not ____________.
- Asteroids are found between the orbits of _________ and _________ .
Answer: (a) Neptune, (b) Mars, (c) Constellation, (d) Satellite, (e) Stars, (f) Mars and Jupiter
Question 5: Mark the following statements as true (T) or false (F):
- Pole Star is a member of the solar system.
- Mercury is the smallest planet of the solar system.
- Uranus is the farthest planet in the solar system.
- INSAT is an artificial satellite.
- There are nine planets in the solar system.
- Constellation Orion can be seen only with a telescope.
Answer: (a) F, (b) T, (c), F, (d) T, (e) F, (f) F
Question 6: Match items in column A with one or more items in column B:
| Column A | Column B |
|---|---|
| (1) Inner planets | (a) Saturn |
| (2) Outer planets | (b) Pole star |
| (3) Constellation | (c) Great Bear |
| (4) Satellite of the earth | (d) Moon |
| (e) Earth | |
| (f) Orion | |
| (g) Mars |
Answer: (1) e and g, (2) a, (3) c and f, (4) d
Question 7: In which part of the sky can you find Venus if it is visible as an evening star?
Answer: Western
Question 8: Name the largest planet of the solar system.
Answer: Jupiter
Question 9: What is a constellation? Name any two constellations.
Answer: A group of stars which resembles certain shape is called a constellation. Great Bear and Orion are two examples of constellation.
Question 10: Name two objects other than planets which are members of the solar system.
Answer: Comets and Asteroids
Question 11: Explain how you can locate the Pole Star with the help of Ursa Major.
Answer: Follow these steps for locating the pole star:
- Locate the Ursa Major and locate the quadrilateral in it.
- Select the two stars on the far side of the quadrilateral.
- Join these stars with a line and extend this imaginary line towards the top of the ladle.
- A faint star which meets this line is the pole star.
Question 12: Do all the stars in the sky move? Explain.
Answer: All the stars move but their movement is not perceptible to us. Instead of that; it is the rotation of the earth which creates an illusion of the movement of stars across the sky. But the pole star appears to be fixed at its position. This happens because the pole star is in line with the axis of the earth.
Question 13: Why is the distance between stars expressed in light years? What do you understand by the statement that a star is eight light years away from the Earth?
Answer: The interstellar distances or intergalactic distances are too big to be easily expressed in terms of kilometers. Hence, we need a more convenient unit to express them. A light year is the distance travelled by light in one year. If a star is eight light years away from the earth, then it means that the light from that star takes eight years to reach us. This also means that the star which appears to our eyes is in fact the way it looked eight years ago.
Question 14: The radius of Jupiter is 11 times the radius of the Earth. Calculate the ratio of the volumes of Jupiter and the Earth. How many Earths can Jupiter accommodate?
Answer: We know that the ratio of volumes of two spheres is the ratio of cubes of their radii.
Radius of Earth = R
Radius of Jupiter = 11R
Volume of Jupiter ÷ Volume of Earth
11R3 ÷ R3 = 1331
It is clear that the Jupiter will accommodate 1331 earths.