Physics · Earth and space
Lunar Eclipse
A lunar eclipse happens when the Earth comes between the Sun and the Moon and the Earth’s shadow falls on the Moon.
- What people see
- Total lunar eclipse (red “blood moon”)
- Moon’s phase
- Full moon
- Safe to watch?
- Yes — no glasses needed
Try this
- Move the Moon to full moon on the line. What colour does it turn?
- Move it a little above the line. Which kind of eclipse is it now?
- Why can everyone on the night side of the Earth see a lunar eclipse at the same time?
Key ideas
- A lunar eclipse can only happen at full moon.
- Umbra: the dark central shadow. Penumbra: the paler outer shadow.
- In a total lunar eclipse the Moon often looks red, because a little sunlight is bent through the Earth’s atmosphere onto it.
- A lunar eclipse is safe to watch with your eyes.