Class 8 Science Our Universe Question- answers

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Understand and fill in the blanks:

  1. Ursa Major: Saptarishi:: Orion:: Hunter
  1. Full Moon::: New Moon: Amawasya:: Purnima
  1. Earth : Blue Planet : : : Red planet:: Mars
  1. Venus : : : Mars : Mangal:: Shukra
  1. Stars: have light and heat:: Planets:: have no heat and light.

Very Short Answer Questions?

Q1. Define a light year.

Ans.  A light-year is a unit of distance. It is the distance that light can travel in a year.

Q2. What is a pole star?

Ans. Polestar, also spelt pole star, also called (Northern Hemisphere) North star, the

brightest star that appears nearest to either celestial pole at any particular time.

Q3. What are stars? Give examples.

Ans. Stars are giant, luminous spheres of plasma. There are billions of them including our

own sun in a milky way galaxy. Stars are the celestial objects (like the sun) that are extremely hot and have a light of their own.

Q4. What are satellites?

Ans. A satellite is a moon or machine that orbits a planet. For example, Earth is a satellite because it orbits the sun. Likewise, the moon is a satellite because it orbits the earth.

Q5. Write the uses of artificial satellites.

Ans. Thousands of artificial or man-made satellites orbit the earth. Some take pictures of the planet

that help meteorologists predict weather and track hurricanes. Some take pictures of other

planets, the sun, black holes, dark matter or faraway galaxies. These pictures help scientists

to better understand the solar system and the universe. Still, other satellites are used, mainly for communications, such as beaming TV signals and phone calls around the world.

A group of more than 20 satellites make up the global positioning system (GPS). If you have a GPS receiver, these satellites can help figure out your exact location.

 Q6. What is a galaxy?

Ans. A galaxy is a large collection of stars, glowing nebulae (clouds), gas and dust bound together by gravity.

Q7. What are constellations?

Ans. A constellation is a group of stars which form a pattern in the night sky.

Q8. What are comets?

Ans. Comets are cosmic snowballs of frozen gases, rock and dust roughly the size of a small town.

Q9. Which two planets have asteroids between them?

Ans. Mars and Jupiter

Q10. Name the planet having a well-developed system of rings around it.

Ans. Saturn

Q11. Name the planet which rotates from east to west.

Ans. Venus

Q12. Name the one natural and one artificial satellite of the Earth.

Ans. Natural- Moon

Artificial- Sputnik 1

Q13. Name the first satellite launched by India.

Ans. Aryabhatta

Q14. What name is given to the celestial body which revolves around a planet?

Ans. Satellite

Q15. How can you say that the sun is a star?

Ans. All starts emit light and heat.

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