Astronomy Practice Exam

What happens during a lunar eclipse?

1. The Sun, Earth, and Moon align

2. The Moon blocks the Sun from the Earth

3. The Earth blocks sunlight from reaching the Moon

4. The Earth's shadow is cast on the Sun

The correct answer is: The Earth blocks sunlight from reaching the Moon

During a lunar eclipse, the correct scenario described is when the Earth blocks sunlight from reaching the Moon. This occurs when the Sun, Earth, and Moon are aligned in a straight line, with the Earth positioned directly between the Sun and the Moon. As a result, the Earth's shadow is cast on the Moon, leading to the phenomenon of a lunar eclipse. In this process, the Earth's shadow comes in three parts: the penumbra, where partial shadow occurs; the umbra, where total shadow exists; and the antumbra. When the Moon passes through the umbra, it can appear reddish in color, often referred to as a "blood moon," due to Rayleigh scattering—similar to the effect that causes sunsets to appear red when sunlight passes through a thicker atmosphere. For context, the other options describe different celestial alignments or events. The alignment of the Sun, Earth, and Moon does occur during a lunar eclipse, but it specifically pertains to the Earth's blocking of sunlight. The second option mistakenly suggests that the Moon is blocking sunlight from the Earth, which describes a solar eclipse instead. The last option about the Earth's shadow being cast on the Sun is also incorrect in this context, as this scenario does not happen during a lunar