Question

Suppose you live on the Moon and your home is located near the centre of the face that we see from Earth.

i) How long would your "lunar day" be? By "lunar day" I mean from when the Sun is on your meridian - your local "lunar noon" - to the next "lunar noon".

ii) If the Moon is full (as seen from Earth), what phase would you see for the Earth (new earth, first-quarter earth, full earth, etc)? Would it be day or night on the Moon? Explain.

iii) When you see sunrise on the Moon, in what phase would the Moon be (as seen from the Earth)? In what phase would you see the Earth at this time?

iv) What would you see if you were on the Moon during a total lunar eclipse?

v) What would you see if you were on the Moon during a total solar eclipse?

vi) Suppose the distance from Earth to the Moon were twice its actual value. Would it still be possible to see a total solar eclipse from Earth? Why or why not?

Answer 1

1) As moon's rotation and revolution around itself and the earth is about the same, so a lunar day is equal to on lunar month of earth = 29.53 earth-days.

2) If it's full moon from Earth, then Earth's night part will face the moon's "Day" part, so it could be called a "New Earth" Phase.

3) When the central part of the full moon is facing sunrise, the configuration is like this :

This is known as the first quarter phase of the moon.
From moon the moon the situation will be exactly opposite, as the earth will be at its last quarter phase.

4) During a total lunar eclipse, the moon is shaded completely behind the earth's shadow. This means that from the moon a total solar eclipse will happen.

5) During a total solar eclipse the moon will face back from the sun and directly on day part of the earth, so it will see a small shadow over the earth's surface.

6) If the moon goes twice as far as it is now, the relative size of the moon with respect to sun will decrease, this'll imply that the Sun won't be completely covered by the moon. So no total solar eclipse anymore.