The progression of changes in the Moon's appearance during the month is called what?

• A. Lunar Eclipse
• B. Seasons
• C. Phases of the Moon
• D. H-R Diagram

Answer: (C)

The progression of changes in the Moon's appearance as it orbits Earth is called the phases of the Moon. This happens because sunlight shines on the Moon and, from our viewpoint on Earth, we see different amounts of the lit half as the Moon moves along its orbit. Over about 29.5 days, we observe a cycle that starts with a new moon, followed by crescents, a first quarter, a full moon, and then waning phases back to a last quarter and new moon again. It’s the regular, repeating change in the visible shape of the Moon, not an eclipse or any other kind of event. A lunar eclipse is when Earth blocks sunlight from reaching the Moon, seasons are caused by the tilt of Earth’s axis relative to the Sun, and the H-R diagram is a chart used for stars.