Back to today’s briefing

Story perspectives

Understanding Moon Phases: Orbit, Light, and Earthshine

8/25/2025

22 4

Summary

Story summary

The moon's phases are caused by its orbit and the reflection of sunlight, not by any light it generates.
A crescent moon appears after the new moon, often accompanied by "Earthshine" visible shortly after sunset.
The full moon occurs 14 days after the new moon, hindering stargazing due to direct sunlight on the surface.
The moon rises later each day, shifting eastward among the stars by approximately 13 degrees every 24 hours.

History

Historical Context

In 1609, Galileo Galilei revolutionized astronomy by using a telescope to observe celestial bodies, revealing that the moon reflects sunlight. This contradicted the Church's teachings and enhanced navigation and agriculture through a better understanding of lunar phases. Galileo's work laid the groundwork for modern astronomy, influencing our perception of the universe and celestial mechanics.

1 of 2

Story summary

The moon's phases are caused by its orbit and the reflection of sunlight, not by any light it generates.
A crescent moon appears after the new moon, often accompanied by "Earthshine" visible shortly after sunset.
The full moon occurs 14 days after the new moon, hindering stargazing due to direct sunlight on the surface.
The moon rises later each day, shifting eastward among the stars by approximately 13 degrees every 24 hours.

1 / 2