Geometry of the New Moon
Understand the geometry of the new moon in Grade 8 astronomy. Students learn that when the Moon is positioned between the Sun and Earth, sunlight illuminates only the Moon's far side—leaving the Earth-facing side in shadow and making the Moon appear invisible from Earth.
Key Concepts
When the Moon is positioned between the Sun and Earth, the sunlight hits the "far side.".
The side facing Earth is in its own shadow (Night Side). This alignment results in a New Moon , where the Moon appears invisible from Earth.
Common Questions
Why can't we see the moon during a new moon?
During a new moon, the Moon is between the Sun and Earth. Sunlight hits the Moon's far side—the side facing away from Earth. The side facing Earth is in shadow, so there is no reflected light traveling toward us and the Moon appears invisible.
What is the geometry of the Sun-Moon-Earth alignment during a new moon?
A new moon occurs when the Moon is positioned between the Sun and Earth, roughly aligned in a straight line. The Sun illuminates the Moon's far side while the near side (facing Earth) is in the Moon's own shadow, making it appear dark from our perspective.
If the moon is invisible during a new moon, how do we know it's there?
The Moon's position is tracked by its gravitational effects and its predictable orbital period. Also, a solar eclipse—which can only occur during a new moon—is dramatic proof the Moon is physically present between the Sun and Earth, just not illuminated toward us.