天文學問題 (物理)

1(a) 1800 hr is around sunset time. The moon is at the top of the dotted circle, and you are on the "top" of the earth.

(b) west

(c) Around mid-night

(d) Fig. B

(e) It is the first quarter, i.e. around day 7.

(f) The tides are weak, as the gravitational pulls from the sun and earth do not align in the same straight line.

2(a)


圖片參考：https://s.yimg.com/rk/HA00458726/o/1334906883.jpg



(b) The main factor is the distance of the Moon from Earth when an eclipse occurs. An annular solar eclipse is observed when the Moon moves centrally in front of the Sun, but it is so far away from Earth that it appears smaller in the sky and cannot cover the Sun completely. The Sun's outer edges are then still visible and form a “ring of fire” around the Moon.

(c) A partial solar eclipse is seen when the observer is located in the penumbra of the moon. We can see the moon because it reflects sunlight towards the earth. In a lunar eclipse, because the earth is much larger than the moon, a partial eclipse is thus not observed during a total eclipse of the moon.