Lesson: Star and the Solar System

# Question: 1

Which of the following is not a member of the solar system?
(a) An asteroid
(b) A satellite
(c) A constellation
(d) A comet

c

# Question: 2

Which of the following is not a planet of the sun?
(a) Sirius
(b) Mercury
(c) Saturn
(d) Earth

a

# Question: 3

Phases of the moon occur because
(a) we can see only that part of the moon which reflects light towards us.
(b) our distance from the moon keeps changing.
(c) the shadow of the Earth covers only a part of the moon's surface.
(d) the thickness of the moon's atmosphere is not constant.

a

# Question: 4

Fill in the blanks:
(a) The planet which is farthest from the sun is _________.
(b) The planet which appears reddish in colour is _________.
(c) A group of stars that appear to form a pattern in the sky is known as a _____.
(d) A celestial body that revolves around a planet is known as a_________.
(e) Shooting stars are actually not _________.
(f) Asteroids are found between the orbits of __________ and _________.

## Solution:

(a) The planet which is farthest from the sun is Neptune.
(b) The planet which appears reddish in colour is Mars.
(c) A group of stars that appear to form a pattern in the sky is known as a constellation.
(d) A celestial body that revolves around a planet is known as a satellite.
(e) Shooting stars are actually not stars.
(f) Asteroids are found between the orbits of Mars and Jupiter.

# Question: 5

Mark the following statement as true (T) or false (F).
(a) Pole star is a member of the solar system. ( )
(b) Mercury is the smallest planet of the solar system. ( )
(c) Uranus is the farthest planet in the solar system. ( )
(d) INSAT is an artificial satellite. ( )
(e) There are nine planets in the solar system. ( )

(f) Constellation Orion can be seen only with a telescope. ( )

(a) False

(b) True

(c) False

(d) True

(e) False

(f) False

# Question: 6

Match items in column A with one or more items in column B.

 A B (i) Inner planets (a) Saturn (ii) Outer planets (b) Pole star (iii) Constellation (c) Moon (iv) Satellite of the Earth (d) Great Bear (e) Earth (f) Orion (g) Mars

## Solution:

 A B (i) Inner planets (g), (e) Mars, Earth (ii) Outer planets (a) Saturn (iii) Constellation (d), (f) Great Bear, Orion (iv) Satellite of the Earth (c) Moon

# Question: 7

In which part of the sky can you find Venus if it is visible as an evening star?

## Solution:

If Venus is visible as an evening star, then it must be in the western part of the sky.

# Question: 8

Name the largest planet of the solar system.

## Solution:

The largest planet of the solar system is Jupiter.

# Question: 9

What is a constellation? Name any two constellations.

## Solution:

A group of stars that forms a specific pattern in the sky is called a constellation.
Ursa Major and Orion are two constellations.

# Question: 10

Draw sketches to show the relative position of prominent stars in

(a) Ursa Major and

(b) Orion.

## Solution:

a)      There are three bright stars in a line while four stars are there in the form of a rectangle, as shown in the figure.

b)      There are three bright stars in what is well known as the Orion’s belt, while five bright stars form a quadrilateral, as shown in the figure.

# Question: 11

Name two objects other than planets which are members of the solar system.

## Solution:

Asteroids and meteors

# Question: 12

Explain how you can locate the Pole Star with the help of Ursa Major.

## Solution:

With the help of the Ursa Major constellation, the pole star can be located. This can be done by drawing an imaginary line connecting the two stars present at the end of the square or rectangular structure formed by the four stars. This imaginary line is then extended in the north direction until it touches the Pole Star.

# Question: 13

Do all the stars in the sky move? Explain.

## Solution:

No, the stars in the sky do not move. Due to rotation of the earth on its axis from west to east, the stars appear to move from east to west.

# Question: 14

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?

## Solution:

The universe is vast and objects in the universe are separated by large distances. For example, if the distance between the sun and the nearest star Proxima Centauri is taken as 40,000, 000,000,000 km, it becomes inconvenient to write these long digit numbers. In order to simplify this, the concept of light year was introduced. A light year is defined as the distance travelled by light in one year. Light travels very fast, at a velocity of 3 lakh kilometre per second. So, in one year, it travels about 9.46 x 1012 km. Therefore, using light year calculations, distance between the sun and the nearest star Proxima Centauri is said to be approximately 4.24 light years.

If a star is located 8 light years away from the Earth, this means that the distance between the star and the Earth is equivalent to the distance travelled by light in eight years, i.e., a star is located $8×\left(9.46×{10}^{12}\right)=7.6×{10}^{13}$ km away from the Earth.

# Question: 15

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?

## Solution:

Let us consider Earth and Jupiter to be two spheres with radii R and R' respectively. Given that the radius of Jupiter is 11 times the radius of the Earth.
Thus, R' = 11 R

Volume of sphere of the radius r is given as $=\frac{4}{3}\pi {r}^{3}$

Volume of the earth $=\frac{4}{3}\pi {r}^{3}$

And, volume of Jupiter $=\frac{4}{3}\pi {\left({R}^{\prime }\right)}^{3}=\frac{4}{3}\pi {\left(11R\right)}^{3}=1331\left(\frac{4}{3}\pi {R}^{3}\right)$

The ratio of the volume of Jupiter and Earth

Hence, this ratio suggests that Jupiter can accommodate 1331 number of Earths within it.

So, it can be concluded that Jupiter can accommodate 1331 number of Earths.

# Question: 16

Boojho made the following sketch of the solar system. Is the sketch correct? If not, correct it.

## Solution:

No, the sketch made by Boojho is incorrect because Mars and Venus have been interchanged. Same goes for the position of Uranus and Neptune. The Asteroid belt is shown between the orbits of Jupiter and Saturn, which is wrong. The asteroid belt should be between the orbits of Mars and Jupiter as shown in the sketch below.