Question

At what phase are the Earth, Moon and Sun are in approximate alignment?
A. Full Moon
B. New Moon
C. Waning crescent
D. Waxing Crescent

Answer 1

Hint:To solve this problem, first, we study all phases of the moon. Some people believed that phases come from Earth's shadow cast on the moon. Some thought that the moon changes shape due to clouds. These are common misconceptions, but they're not true. Instead, the moon's phase depends only on its position relative to Earth and therefore the Sun.

Complete step by step answer:
Different phases of the moon are:

The new moon occurs when the Moon, Earth, and Sun lie in the same line. Since the Sun is behind the Moon from Earth's perspective, the moon's side facing Earth is dark. At full moon, the three bodies also lie in a line, but this time, the moon is on the opposite side of Earth, so the Sun illuminates the whole side facing us.
In the first quarter and last quarter, the moon lies perpendicular to a line between Earth and the Sun. We see exactly half of the moon illuminated by the Sun — the opposite half lies in shadow. The "quarter" used to name these phases.

After the new moon, a slice of reflected sunlight becomes visible as a waxing crescent. The lunar crescent grows until the first-quarter moon. As the moon's sunlight portion continues to increase to more than half of the moon's face, the moon turns waxing gibbous. Then, after the full moon, the sunlit fraction begins to decrease again to make a waning gibbous and then a third-quarter Moon. The portion of sunlight decreases until the moon is a waning crescent and then a new Moon. The whole cycle takes about 29.5 days.

From the above discussion we found that the correct answer is (B) i.e. “new moon”.

Note: The illuminated part of the moon gradually shows transitions between these phases. Remember the in-between phases you will need to know these terms: crescent, gibbous, waxing, and waning. Crescent refers to phases where the moon is less illuminated, while gibbous means more than half of the moon is illuminated. Waxing means expands in illumination and waning means "shrinking" in illumination.