Key Idea.
Section 1
The Rareness of Eclipses
If a Full Moon happens every month, why don't we have a lunar eclipse every month?
The answer relates back to Scale. Earth's shadow is a narrow target far out in space. For the Moon to hit this target, the Sun, Earth, and Moon must form a perfect straight line.
Section 2
The Missing Variable
Most of the time during a Full Moon, the alignment is imperfect. From a "top-down" view, they look aligned, but from a "side" view, they are not.
This implies there is a vertical difference in the system preventing the shadow from hitting the Moon every month.
Expand to review the lesson summary and core properties.
Section 1
The Rareness of Eclipses
If a Full Moon happens every month, why don't we have a lunar eclipse every month?
The answer relates back to Scale. Earth's shadow is a narrow target far out in space. For the Moon to hit this target, the Sun, Earth, and Moon must form a perfect straight line.
Section 2
The Missing Variable
Most of the time during a Full Moon, the alignment is imperfect. From a "top-down" view, they look aligned, but from a "side" view, they are not.
This implies there is a vertical difference in the system preventing the shadow from hitting the Moon every month.