Chapter 1 - Our Earth and Our Solar System
EXERCISES
1. What’s the solution ?
One of the asteroids has fallen out of its place in the asteroid belt and is hurtling towards the sun. Our earth is in its way and there is all likelihood of a collision. What can be done to prevent this collision?
Ans:
(a) The first act to save the earth can be attacking the asteroid with a missile. A missile can break an asteroid into smaller pieces.
(b) The second way is to change the path of an advancing asteroid. For changing the path of the asteroid, a spaceship or missile can be used to push it aside.
(c) A space shuttle fitted with mirrors can be used so that the reflected sunrays from such a mirror can be bombarded on the asteroid. This will create pressure on the asteroid, and its advancing path can be changed.
(d) By using laser rays, the surface of an asteroid can be subjected to evaporation. This will cause a change in the mass of the asteroid. We can also send extra material to the asteroid from Earth. Such a change in the mass of an asteroid changes its orbit and path.
(e) By placing a space shuttle in the vicinity of this asteroid, a gravitational force could be created. This can also change the speed and path of the asteroid.
(f) Astronomy and astrophysics are so advanced now that even if such a threat exists in the future, we can easily protect our earth’s inhabitants well in advance.
2. Use your brain power !
(1) What will happen to our solar system if the sun were to suddenly disappear ?
Ans: If the sun suddenly disappears,
(a) There would be darkness everywhere.
(b) All the plants will die as they will not be able to perform photosynthesis.
(c) All the planets would stop revolving.
(d) The cycle of day and night would come to a halt.
(e) There will not be weeks or months any more.
(f) There will be uniformly only one season; seasonal changes will come to an end.
(g) All the equipment that runs on solar energy will not work anymore.
(h) There will not be any heat, and the entire earth will be cold.
(i) The water cycle would stop as the water bodies would not evaporate, forming water vapour and then clouds, and thus there would be no rain.
(j) Germs would grow at a rapid pace everywhere on earth, and this would result in the outbreak of many diseases.
(2) Suppose you want to give your address to a friend you have on the planet Mars. How will you write your address if you want them to understand exactly where you live?
Ans:
Amaan Khan,
Taximens Colony,
L.B.S. Road,
Kurla (West),
Mumbai – 400 070,
Maharashtra, India,
Asia, Earth.
3. In the picture below, correct the sequence of the planets from the sun.
Ans: In the above picture, Mars and Earth’s positions are interchanged. Also, the sequence of Jupiter and Saturn is also changed.
Therefore, the wrong sequence in the picture is Mercury and Venus. Mars, Earth, Saturn, Jupiter, Uranus, and Neptune.
The correct sequence should be Mercury, Venus, and Earth. Mars, Jupiter, Saturn, Uranus, and Neptune.
4. Who am I ?
(a) You can see me from the earth but the lighted part of me that you see changes every day.
Ans: Moon
(b) I have my own light. It is only from me that the planets get light and heat.
Ans: Sun
(c) I turn around myself, around a planet and also around a star.
Ans: Satellite
(d) I turn around myself and revolve around the sun.
Ans: Planet
(e) No other planet has a living world like mine.
Ans: Earth
(f) I am the nearest star to the earth.
Ans: Sun
5. (a) For what purpose are rockets used in space travel?
Ans: Space launch technology is used to send the spacecraft into outer space against the force of gravity. It requires a tremendous amount of energy to launch the spacecraft, which is thousands of tons in weight. This energy is obtained through the burning of an ample quantity of fuel present in the rocket. Thus, rockets are used to launch spacecraft in space travel.
(b) What information do man-made satellites provide?
Ans: Man-made satellites provide useful information for agriculture, the environment, weather, forecasting, making maps, and searching for water and mineral wealth on the Earth. They are also used for telecommunications.