How it works
A solar eclipse diagram labeled, with a lunar eclipse below it to compare. Each part lights up in both views.
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Solar eclipse
The Moon passes between the Sun and Earth. Its dark umbra narrows to a small spot on Earth: along that path of totality the Sun is completely hidden. In the wider penumbra, people see only a partial eclipse.
Lunar eclipse
Now Earth is in the middle, and the Moon passes into Earth's shadow. In the umbra it is lit only faintly, and it often looks red, which is why a lunar eclipse is also called a blood moon.
- Never look at the Sun during a solar eclipse without proper protection: it can damage your eyes permanently in a fraction of a second.
Questions and answers
What is the difference between the umbra and the penumbra?
The umbra is the dark centre of a shadow, where the Sun is completely hidden. The penumbra is the paler outer part, where it is only partly hidden.
What is the path of totality?
The narrow track across Earth where the Moon's umbra falls during a solar eclipse. Only along it is the eclipse total.
What is the difference between a solar and a lunar eclipse?
In a solar eclipse the Moon comes between the Sun and Earth and blocks the Sun. In a lunar eclipse Earth comes between the Sun and the Moon, and its shadow falls on the Moon.