SEE Science Questions, Chapter: The Universe

1.The distance between the earth and sun is not same throughout the year.

The distance between the earth and sun is not same throughout the year because the earth revolves round the sun in its elliptical orbit due to which sometimes it lies closes and sometimes it lies farther.

2. The sun rises in the east.

The sun rises in the east became the earth rotates from west to east on its axis. As we travel eastwards on rotating the earth, we pass into the zone of light where we can see the sun. So, that we can see the sun in the east for the first time in the morning.

3. Pluto is not considered as a planet of solar system.

Pluto is not considered as a planet of solar system became its size is very small, its orbit coincides with the orbit of Neptune and its orbit does not lie on the same plane to the plane of other orbits.

4. A comet is seen after a long period.

A comet is seen after a long period because it is seen only when they approaches the sun, It takes many year to complete one revolution around the sun.

Examples: Halleys comet is seen at the interval of 76 years because it takes 76 years to make one complete revolution.

5. Some planets look brighter than stars.

Some planets look brighter than stars because they reflect more light due to close distance to the sun.

6. A meteor lasts for a very short time.

A meteor lasts for a very short time because it burns and vaporize completely due to the excessive heat produced by the friction with atmospheric pressure.

7. The moon raises 50 minutes delay every day.

The moon raises 50 minutes delay every day because when the earth rotates on its axis on 24 hours, the moon revolves the earth at the same time by (360/30) 12degree from its original position. To, rotate 120 more distance; it takes 50 minutes extra time to the earth.

8. Mercury is very hot at day and very cold at night.

Mercury is very hot at day and very cold at night because it lies closer to the sun and it has no atmosphere due to which it is very hot when it receives sun light but it is very clod in the absences of solar radiations.

9. Venus called morning and evening star.

Venus called morning and evening star because it can be seen brighter in the eastern sky dosing morning and in the western sky outing evening.

10. Earth appears blue when viewed from the outer space.

Earth appears blue when viewed from the outer space because of the reflection of light from the water bodies of the earth like see and oceans.

11. Earth is colued a green planet.

Earth is colued a green planet because it is only the planet with suitable environment for the living things.

12. Saturn can float on water.

Saturn can float on water because its density is less than the density of water.

13. Saturn is called a ringed planet.

Saturn is called a ringed planet because it has rings made up of ice pieces on its outer part.

14. The tail of a comet is seen when it approaches the sun but disappears when it is far away from the sun.

The tail of a comet is seen when it approaches the sun but disappears when it is far away from the sun because comet is made up of lamps of ice and when it approaches the sun, it forms a tail due to vaporization of ice and due to pressure of solar wind. But when it is for away from the sun it doesn't happen so and the tail disappears.

15. Black hole is invisible.

Black hole is invisible because it has so extreme gravitation that light cannot escape from it.

16. Some stars look much brighter in a clear sky at night.

Some stars look much brighter in a clear sky at night because the stares with close distance to the earth and having high temperature with bigger size appear much brighter.

17. Mars is called a red planet.

Mars is called a red planet because it appears red when the sun rays fall on the iron containing red mineral on the surface of mars.

18. Neptune takes the longest time to revolve around the sun.

Neptune takes the longest time to revolve around the sun because it lies farthest from the sun among all planets.

19. The heavenly bodies are found moving from east to west in the sky.

The heavenly bodies are found moving from east to west in the sky because the planet rotates from west to east on it axis.

20. A comet is not actually a star.

A comet is not actually a star because they are non-luminous body which appears bright by reflecting the light of the sun. Comet revolves round the sun but star does not revolve round the sun.

21. Some comets disappear forever.

Some comets disappear forever because they waste away or disintegrate when the material is forced out of the head into the other mass and they collide sometimes with other heavenly bodies. Eg. shoe maker -levi will be seen because it was collided with the Jupiter's in 1994 A.D.

22. Temples -tutle comet is seen at the interval of 33 years.

Temples -tutle comet is seen at the interval of 33 years because it takes 33 years to make one complete revelation around the sun.