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Venus is called as the sister planet of the earth because their shape and size is almost similar.

Titan, the satellite of Saturn, has dense atmosphere like the earth. There are rivers, lakes, and the land found there is like that of the earth. The most important gas that is found in the atmosphere there is nitrogen. These conditions suggest presence of life there. The scientists are making efforts to find out whether there is possibility of life there or not.

Asteroids are found in the form of a belt between the planets Mars and Jupiter.

1. d

2. c

3. b

4. e

5. a

All tiny bodies revolving round the sun such as tiny planets, asteroids, meteors, etc., are collectively known as minor bodies.

The moon is spherical in shape and it receives light from the sun. Therefore, the light of the sun falls on the half portion of the moon and its other half always remains in darkness. Once in a month, the moon’s fully illuminated face is visible in front of the earth. In India, it is known as Poornima. In the same way, once in a month, the dark portion of the moon is visible in front of the earth. This condition is known as Amavasiya. From the Poornima to Amavasiya, the illuminated part of the moon keeps on decreasing and from the Amavasiya to Poornima, this part keeps on increasing. These increasing and decreasing shapes of the moon are called the lunar phases.

It has been found by the discoveries made by modern astronomers that the air and water is absent on the moon, therefore life is not found on the moon.

1. the sun 

2. fifth 

3. atmosphere 

4. Satellites

Comets are pieces of meteors or asteroids which get attracted towards the earth due to its gravitational force. 

Following are their characteristics :

1. On their way to the earth, they get burnt due to friction with atmospheric particles. 

2. In the atmosphere, during friction, they appear as shining bodies with long tails which we call as falling stars. 

3. Some comets are so big that they do not diminish completely and they hit the earth’s surface. At this point, they are called as meteors. 

4. When they fall on the earth, they cause hollows on the earth’s surface.

Such celestial bodies which revolve round the sun in their fixed elliptical orbit and also cross the path of other bodies are known as dwarf planets.

The earth is situated between the planets Venus and Mars.

Planets, asteroids and comets collectively form a large celestial group which revolves round the sun. Group of all these celestial bodies along with the sun and the earth is known as the solar system.

The following three major spheres are found on earth:

1. Lithosphere, 

2. Atmosphere, 

3. Hydrosphere.

1. Lithosphere : Lithosphere is the upper most layer of the earth in which mankind lives. Soils and various types of minerals found in the lithosphere are significant for sustenance of life of living organisms present on earth. 

2. Atmosphere : The gaseous cover which surrounds the earth is known as atmosphere. This retains around the earth due to the gravitational force of the earth. Gases have played a significant role in the composition of the atmosphere. Nitrogen and oxygen are the major gases present in the atmosphere. Apart from these, water vapour and dust particles are also present in it. 

3. Hydrosphere : It is spread upon around 71 per cent part of the earth’s surface. Water is found on earth in various oceans, seas, lakes and rivers.

Due to the interaction of all these three spheres, a fourth sphere named biosphere is formed. Living beings, flora and fauna and human beings exist reside in the biosphere itself.

Sequence of planets on the basis of their distance from the sun is- Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune

There are very small planet-like bodies which revolve round the sun in the form of a belt present between the orbits of Mars and Jupiter. These bodies are known as tiny planets.

Following is a comparative analysis of planets Earth and Jupiter Basis of comparison Earth Jupiter:

Answer is: (a) Mercury

In Indian culture, the sun is considered as ‘Grihapati’.

Nicolas Copernicus was the first to interpret about the central position of the sun in the year 1543 AD.

Answer is: (a) 8

Answer is: (c) Venus

Answer is: (b) Saturn

Satellites are small celestial bodies which revolve round the planets. 

For example – Moon, Titan, Ganymede, Demos, Phobos, etc.

Mercury and Venus are such planets which do not have satellites of their own.

1. c, 

2. d, 

3. b, 

4. e, 

5. a.

Answer is: (d) Jupiter

Answer is: (a) Mercury

Major gases present in the atmosphere include – nitrogen, oxygen, carbon dioxide, and argon.

The gaseous cover found all round the earth is known as the atmosphere.

The uppermost layer of the earth is called lithosphere and soil is found there which provides food to all the living organisms. The gaseous layer around the earth is called the atmosphere. Hydrosphere is spread upon around 71 per cent part of the earth. In the entire solar system, lithosphere, hydrosphere and atmosphere are found only on the earth. The i iteraction of these three spheres gives rise to biosphere in which all flora and fauna exist. The information which is available to date in context to the universe suggests that the earth is the only planet where life exists. Therefore, it is known as an amazing and blue planet.

According to modem astronomers, there is no air and water on the moon. Therefore, there is no possibility of life on it.

The planets Earth, Mars, Jupiter, saturn, Uranus, Neptune have their own satellites. Mercury and Venus are such planets which are closest to the sun but they do not have their own satellites.

Soil which is present on the lithosphere provides food to the living organisms on the earth and the minerals found on it are essential for the sustenance of the living beings.

The major reason for no possibility of life on planets which are situated far away from the sun is that they are excessively cold and their density is less.

In India, the ascending lunar phases of days are known as Shukla Paksh (fort night) and the descending lunar phases of days are known as Krishna Paksh (fort night).

On the basis of their size, density and composition, planets have been classified into the following two types :

1. Inner planets – Mercury, Venus, Earth and Mars are inner planets. They are small in size, have greater density and they have been built out of rocks. 

2. Outer planets – Jupiter, Saturn, Uranus and Neptune are outer planets. They are larger in size, have less density and have been built of gaseous or liquid substances.

1. orbit 

2. dwarf planet 

3. sister planet 

4. moon 

5. lunar phases