Question

Read the passage given below and write the option that you consider the most appropriate in your






1. The Sun and the Moon, familiar entities in the sky, are part of a larger family- the solar system -

which comprises nine planets revolving round the Sun satellites that orbit round the planets lots

of minor bodies that include asteroids comets and interplanetary dust. Till recently, the solar

system was the only planetary system known to exist Apart from the Sun planets and their

satellites account for a major part of the Solar system. The nine planets can be divided into two

categories depending on their features-the inner terrestrial planets and the outer planets. The

inner planets, viz. Mercury Venus, the Earth and Mars are mainly rocky and their main mineral

constituents are silicates, iron and magnesium. The outer planets namely Jupiter, Saturn, Uranus

Neptune and Pluto are huge gas planets (with the exception of Pluto) and are made up of

hydrogen, helium methane and ammonia.

2. All objects of the solar system revolve round a central body. It is the Sun in the case of planets,

comets and asteroids, and the planets in the case of satellites. This movement is a consequence

of gravity. To the fest approximation, the motion of the planets can be given by the three laws

of Kepler, Newton was later able to explain the movements on the basis of his theory of

universal gravitation. All planets have an elliptical orbit. The eccentricity parameter indicates

how elliptical the orbits are. Except for Mercury and Pluto, other planets have almost zero

eccentricity and hence the orbits are almost circular. Besides orbiting round the Sun, the planets

also rotate on their axis. The rotational period (sidereal period) is short for most planets except

in the case of Mercury and Venus. The current understanding is that the rotational period of

Mercury and Venus is not the original one but has progressively been reduced (braked)

throughout the history of their formation.



Ques- On the basis of your reading of the above passage, answer the following questions in

your own words.


a. What are the parts of the solar system?


b. How can the nine planets be divided?


c. Which are the inner planets? What is their special feature?


d. Name the outer planets. What are they made of?


e. How does the solar objects move?


f. Who explained the movements of the solar objects?


g. What information do you get about the eccentricity from the passage?


h. Why do all the planets, except Mercury and Venus, have circular orbits?
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Answer 1

Answer:

h ) The rotational period (sidereal period) is short for most planets except

in the case of Mercury and Venus. The current understanding is that the rotational period of

Mercury and Venus is not the original one but has progressively been reduced (braked)

throughout the history of their formation.