Question

Phases of the moon occur because

• A. We can see only that part of the moon that reflects light towards us.
• B. Our distance from the moon keeps changing.
• C. The shadow of the Earth covers only a part of the moon's surface.
• D. The thickness of the moon's atmosphere is not constant.

Answer 1

Answer: (A)

We can see only that part of the moon that reflects light towards us.

Since we know that moon does not have it's own light but it reflects light coming from sun.So as the Moon orbits around the Earth, the part of the Moon that faces the Sun will be lit up. So we can only see that part of moon which is lit up by sun.Shape of lit part depends on relative location of sun,earth and moon.Thus the different shapes of the lit portion of the Moon that can be seen from Earth are known as phases of the Moon.