Question

tania went outside and made two observations of the moon that were several days apart. her observations are shown in the diagram above. the light part of the moon appeared to get larger over time. why did this happen? a between the first observation and the second observation, the moon moved so that tania was able to see more of the half that faces the sun. b between the first observation and the second observation, the moon moved closer to the sun so more sunlight reached the moon’s surface. c between the first observation and the second observation, the moon rotated so that more of the light - colored rock on the moon’s surface faced earth. d between the first observation and the second observation, earth moved so its shadow was blocking less of the moon so tania was able to see more of it.

Explanation:

The Moon's phases are caused by the relative positions of the Earth, Moon, and Sun. As the Moon orbits Earth, the portion of the sun - lit side visible from Earth changes. Option A: The Moon orbits Earth, and as it moves, more of the sun - lit half (the half facing the Sun) becomes visible from Earth, which matches the Moon appearing larger (more illuminated) over time. Option B is incorrect because the Moon's distance from the Sun doesn't change significantly in a few days to cause such a visible change in illumination. Option C is incorrect as the Moon's rotation is synchronous (it rotates once per orbit, so the same side faces Earth), and rotation doesn't cause the illuminated portion visible from Earth to increase in this way. Option D is incorrect because Earth's shadow causing lunar phases is for eclipses, not the regular lunar phases shown here (the Moon is not in Earth's shadow in these observations; it's a phase change due to orbital position).

Answer:

A. Between the first observation and the second observation, the Moon moved so that Tania was able to see more of the half that faces the sun.