Question and Answers Of Stars and Solar system 8th Class science

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KEYWORDS

    

     Asteroids:- The small pieces of rocks or metals which revolve around the sun, in between the orbits of mars and jupiter is called Asteroids.

    Celestial bodies:- Bodies such as, the earth, the moon, the planets, the sun, the stars, the comets, etc are celestial bodies.

    Comets:- The bright "star-like" object with a long tail approaching the sun in a highly elliptical orbit  is known as comets.

    Light year:- The distance travelled by light in one year is called light year.

    Meteor:- A bright "star-like" object which suddenly appears in the sky and then for a few movements streaks in the form of a brilliant flashes towards the earth.

    Meteorites:- The unburnt piece of meteor, which reach the surface of the earth.

    Natural Satellite:- The celestial body/bodies revolves around the planets are known as natural satellite.

    Orbit:- The path along which celestial bodies revolve around the sun or other celestial bodies.

    Phases of moon:- The waxing and waning of the disc of the moon as it revolves around the earth are called the phases of moon.

    Planets:- The  celestial bodies which revolve around the sun in well defined orbits.

    Pole star:- A star in line with north pole of the earth, whose position does not change is called pole star.

    Shooting star:- Same like the meteor.

    Stars:- Giant balls of fusing hydrogen and helium which emit huge amount of heat and light are known as stars.

Question No 1:-Fill in the blanks:

1. The branch of science which deals with the study of ________ is called astronomy.
2. The unburnt part of a meteor which reaches the earth is called________.
3. The heavenly bodies which revolve around the sun are called ________.
4. The heavenly bodies which revolve around the planets are called ________. 
5. The orbit of _______ is not in the same plane as that of the other planets.
6. A heavenly body with long tail, moving around the sun in an elliptical path is called _______.
7. In the _______ of the sun, hydrogen gas fuses with the liberation of the energy.
8. A group of stars which resembles an animal or some other noun object is called _____. 

Answers:   

1. The branch of science which deals with the study of universe is called astronomy.
2. The unburnt part of a meteor which reaches the earth is called meteorite.
3. The heavenly bodies which revolve around the sun are called planets.
4. The heavenly bodies which revolve around the planets are called moon.
5. The orbit of pluto is not in the same plane as that of the other planets.
6. A heavenly body with long tail, moving around the sun in an elliptical path is called comet .
7. In the core of the sun, hydrogen gas fuses with the liberation of the energy.
8. A group of stars which resembles an animal or some other noun object is called constellation.

Answer the following questions:

Question No 01:- What is universe? Name six different kinds of heavenly bodies found in the universe?

Answer:-Universe: It is the vast un- imaginable space which has in it distant stars, planets and all other things that exist.

The six different kinds of heavenly bodies found in the universe are : 

(1) Earth

(2) Moon

(3) Planets

(4) Sun

(5) Stars

(6) Meteors

Question No 02:-With the reference to the average distance from the sun, state:

(a)The serial number of the planet earth.

Answer:- The serial number of the planet earth is third.

(b) The average distance of the earth from the sun.

Answer:-The average distance of the earth from the sun is: 149.6 million km.

(c) The time taken by sunlight to reach earth:

Answer:-speed of light =3×10⁵ km/sec.

Distance of earth from the sun = 1.5×10⁸km

Time taken by sunlight to reach earth = Distance covered / speed of light.

                    =1.5×10⁸÷3×10⁵

                    =1÷2×10³ sec

                    =500 sec

                    =500÷60 min                      

                    =8.3 minutes

Question No 03

 (a) Name the natural satellite of the earth?  

      

  Answer:- The natural satellite of the earth is moon.

(b) In how many days does this satellite complete one revolution around the earth? 

Answer:-The moon complete one revolution around the earth in 27 ^1/3 days.

(c) In how many days does this satellite rotate around its own axis?

Answer:-The moon rotate about its own axis in 27 ^1/3 days.

(d) How does the gravity of this Satellite compare with the earth?

Answer:- The gravitational pull of the moon is 1/6th that of the earth.

(e)State the maximum temperature on the day side and minimum temperature on the night side of this Satellite? 

Answer:- Maximum temperature of the day side on the moon = 110°C. Minimum temperature of the night side on the moon = -150°C.

Question No 04:-What do you understand by the following terms(a) New Moon (b) Full moon?

Answer:-(a) A new moon (also called the dark of the moon) occurs when the moon is between the earth and the moon, the near side of the moon is the dark side.The moon cannot be seen and we call this new moon.

(b) Full moon:- A Full Moon occurs when the Moon is on the far side of the Earth from the When the earth is between the sun and the moon, the near side is the light side. We call this full moon, even though we only see half the moon.

Question No 05:-(a)Define solar system?

  Answer:- Solar system. The sun along with the eight planets and their moons constitutes the solar system.

 (b) Name all the planets in the solar system in the order of their distance from the sun?

  Answer:-The planets in the solar system in the order of their distance from the sun are given:
    (1) Mercury (2) Venus (3) Earth (4) Mars (5)Jupiter (6) Saturn (7) Uranus (8) Neptune.

Question No 06:-How many moons mars have?

Answer :- Mars have two moons.

(b) Write the name of these moons?

Answer:- The name of these moons are Photos and Deimos.

Question No 07:-What are comet?Why does comet develop a tail while approaching the sun?

Answer:-The bright 'star-like' objects with a long tail, approaching the sun in a highly elliptical orbit, are called comets. Because of the pressure of solar radiations, the tail of the comet consisting of gaseous matter always point away from the Sun.

Question No 08:- What is star? What make the star give out vast amount of energy? 

Answer:- Star: A self luminous heavenly body in the space is called a star consisting mainly of gases like hydrogen they also contain helium and dust the change in the life of the star is very slow as compare to our own short life. Star life span is billion of year as. Star are classified according to their brightness, temperature, colour and size. Due to the fusion of hydrogen atom large amount of energy is liberated from the star which is it main source of vast energy.

Question No 09:- (a) How are meteors different from stars?

Answer:- The main difference between Meteors and Star is given below: 

                     METEORS

(1) Meteors are mostly made of rocks, metals and dust.

(2) Meteors produce heat and light energy due to friction of air when they enter the atmosphere.

(3) Meteors are very small pieces of rocks. It may be a small as dust particle.

(4) Meteors last for short period (a few second).

                      STAR

(1) Star mostly consist of hydrogen and helium.

(2) Stars produce heat and light energy due to fusion of hydrogen into helium.

(3) Stars are very big in size.

(4) Star life span is billion of years.

(b) How are meteors different from the meteorites?

Answer:-The main difference between meteors and meteorites are given below:

                METEORS

1. Meteors are the sky pieces of planets with exploded and broke up long ago and are now seen floating in space.

2. As soon as they enter the earth atmosphere, they catch fire due to the heart of friction between air and the rock pieces. These burning piece move with great speed and look like streaks of light and are known as meteors. Most of the meteors burn up completely before they fall on the surface of earth.

           METEORITES

1. Sometimes, meteors are big in size. When these meteors enter the earth atmosphere, they do not burn completely and reach the surface of earth. These unburnt pieces ( left - over) of meteors reaching the earth surface are known as meteorites.