🌘 Make an eclipse

Line up the Sun, Moon and Earth, and make the Moon’s shadow land on the Earth. Why doesn’t it happen every month?

The Moon’s shadow
The Moon goes round the Earth about once a month. In sunshine, it casts a long shadow out into space. A solar eclipse is when the Moon passes between the Sun and the Earth, and its shadow falls on us.
Line them up
Slide the Moon round its orbit. Can you make its shadow land on the Earth? The little sky picture shows the Sun as someone under the shadow sees it.
Dark middle, pale edge
The Moon’s shadow has two parts. In the small dark middle, the umbra, the Sun is covered completely. In the big pale edge, the penumbra, only part of the Sun is covered.
Why not every month?
A new moon, when the Moon is between the Sun and the Earth, comes about once a month. So why don’t we get a solar eclipse every month? Try the three buttons.
A real eclipse
On 12 August 2026, the Moon’s dark shadow raced from the far north of Russia, past Greenland and Iceland, and over the Atlantic. Much of Europe saw a partial eclipse. The line shows the middle of the shadow’s path.
Watch it safely
Never look straight at the Sun, not even when the Moon covers most of it. Use proper eclipse glasses, or a pinhole projector: stand with your back to the Sun, and a small hole in a card shines a tiny picture of it onto paper. Ask a grown-up to help.

⭐ Remember

A solar eclipse happens when the Moon passes between the Sun and the Earth, and its shadow lands on us.
In the dark middle of the shadow, the whole Sun is covered. In the pale edge, only part of it is.
The Moon’s orbit is tilted about 5°, so at most new moons its shadow misses the Earth.

The globe pictures are simplified to show the idea. Earth images: NASA Blue Marble (public domain).