I. Answer the following questions1. How does a planet differ from a star?
Ans. Planets are the celestial bodies that do not have their own light and heat but are lit by the light of nearest the stars. Planets revolve around a star. While stars are huge celestial bodies that are made up of gases and have their own light and heat and emit these in large amounts.
2. What is meant by 'Solar System'?
Ans. Solar system is known as solar family with Sun as the head of the family and it consists of eight planets revolving round Sun, satellites revolving round the planets and other heavenly bodies like asteroids and meteoroids.
3. Name all the planets according to their distance from Sun.
Ans. Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
4. Why is Earth called a unique planet?
Ans. Earth is the third nearest planet to Sun and is neither too hot nor too cold. Earth has water on its surface and an envelop of air which contains oxygen - life-supporting gas. All these favorable conditions that support life are probably found only on Earth. Hence, Earth is called a unique planet.
5. Why do we see only one side of the moon always?
Ans. We always see only one side of the moon because moon takes 27 days to complete one revolution round the Earth and it takes the same time to complete one spin / rotation.
6. What is the Universe?
Ans. Millions of galaxies make the Universe. Each galaxy is a huge system of billions of stars and clouds of dust particles and gases.
II. Tick the correct answer1. The planet known as the 'Earth's Twin' is
Ans. (iii) Venus
2. Which is the third nearest planet to Sun?
Ans. (ii) Earth
3. All the planets move around the Sun in a
(i) Circular path
(ii) Rectangular path
(iii) Elongated path
Ans. (iii) Elongated path
4. The Pole Star indicates the direction to be
Ans. (ii) North
5. Asteroids are found between the orbits of
(i) Saturn and Jupiter
(ii) Mars and Jupiter
(iii) Earth and Mars
Ans. (ii) Mars and Jupiter
III. Fill in the blanks1. A group of stars forming various patterns is called a constellation.
2. A huge system of stars is called galaxy.
3. Moon is the closet celestial body to our Earth.
4. Earth is the third nearest planet to the Sun.
5. Planets do not have their own light and heat.