How it works
Most months, the new Moon passes slightly above or below the Sun from our viewpoint. An eclipse requires new moon near one of the points where the orbital planes cross.
What people often miss
Totality is visible only along a narrow path because the Moon's dark central shadow covers a small part of Earth. Other locations may see a partial eclipse.
Why this question comes up
The necessary alignment is precise even though new moon occurs regularly.
Key points
- A solar eclipse does not happen every new moon because the Moon's orbit is tilted relative to Earth's path around the Sun.
- Most months, the new Moon passes slightly above or below the Sun from our viewpoint. An eclipse requires new moon near one of the points where the orbital planes cross.
- Totality is visible only along a narrow path because the Moon's dark central shadow covers a small part of Earth. Other locations may see a partial eclipse.
Bottom line
A solar eclipse does not happen every new moon because the Moon's orbit is tilted relative to Earth's path around the Sun.
Source and verification
This Answer was checked against NASA Science. Follow the source for the full official explanation and any later updates.