observing the night sky

Observing the night sky

D1.Why do we usually not see the stars during the day?

Ans:We do not see stars during day time because sun is very close to  earth that other  stars. sun light dominate the lights of other stars ,so we  do not  see stars during the day time.

D2.In which part of the sky are we likely to find Venus when it is visible as evening star?

Ans:We usually find Venus in very low near the horizon in the sky.

D3.State the causes of the apparent motion of the sun from east to west?

Ans:The apparent movement of sun from east to west is due to the rotation of earth on its axis from  west to east.

D4.Name the special star in the northern hemisphere .Why  has it been useful for travelers?

Ans: Pole star is the special star of northern hemisphere. It remain along the axis of  earth and do not change its position due to rotation of earth. It always pointed north direction, So it is very helpful for traveler to determine the direction.

E1.Define the term constellation?

Ans:A constellation is a group stars that appears to form some recognizable pattern or shape in the sky.

E2.In what respects is the pole star different from other stars?

Ans: Pole star lies along the axis of earth .so it  do not changes its position due to rotation of earth, where as other stars apparently move from east to west due to rotation of earth.

E3.Write two points of difference between a planet and a star.

Stars	Planets
i) stars have their own light	i) planets do not  have their own light
ii) Stars appear like a point	ii) Planets appears as tiny disc
III) stars twinkle	iii) Planets do not twinkle
iv) stars do not change their relative position with other	iv) Planets change their relative position.

E4.   Why do stars appears to slightly shift their position in the night sky?

Ans:The stars appears  to slightly shift their position in the night sky due to rotation of earth on its own axis from west to east. The shift stars is apparent.

E5. Why do stars appear as points to us?

Ans: Star is a huge gaseous ball present very far away from earth. Due to their very large distance from us  they appear just like point.