Moon and Sun look alike

The idea

Though the Moon is much smaller than the Sun, it is much closer to the Earth, so their apparent sizes are similar and the Moon can appear to cover the entire Sun.

Two round faces in the sky

The Moon is much smaller than the Sun. Yet in the sky they look about the same size.

How can that be?

• The Moon is much closer to us
• The Moon shines brighter than the Sun
• The Sun shrinks at noon

Lines of sight

The picture is not to scale. Try a what-if: move the Moon away, then back to where it really is.

Small and near, big and far

The Moon is much closer, so it looks about as big as the Sun. This is why the Moon can appear to cover the whole Sun.

Though the Moon is much smaller than the Sun, it is much closer to the Earth, so their apparent sizes are similar and the Moon can appear to cover the entire Sun.

Notes

Though the Moon is much smaller than the Sun, it is much closer to the Earth, so their apparent sizes are similar and the Moon can appear to cover the entire Sun.

Check yourself

Compared to the Sun, the Moon is …

Compared to the Sun, the Moon is much …

From the Earth, the Sun and the Moon have …

Because of this, the Moon can …

• the same size. The Moon is much smaller than the Sun, though it looks about as big.
• much smaller — correct. Yes! But it looks about as big because it is near.
• much bigger. The Moon is much smaller than the Sun.
• farther from the Earth. The Sun is the farther one.
• hotter. The Moon’s temperature has nothing to do with its apparent size. The reason is its distance.
• closer to the Earth — correct. Yes! That is why it looks as big as the Sun.
• similar apparent sizes — correct. Yes! The Moon is small but near.
• no apparent size at all. Both appear as round discs in the sky, with a size we can see.
• very different apparent sizes. Their apparent sizes are similar.
• cover the Sun every single day. The Moon covers the Sun only at certain times, at a solar eclipse.
• appear to cover the entire Sun — correct. Yes! This happens at a solar eclipse.
• change the real size of the Sun. The Moon cannot change the Sun. It only blocks the light.