月が大きく見える理由は？地平線の月は錯覚です

Why Does the Moon Look So Big Near the Horizon?

Have you ever seen a huge moon rising above the houses?

It looks much bigger than the moon high in the sky.

But the moon does not really change its size.

This is called the moon illusion.

You can check it with your own hand.

Hold out your arm and put your fingernail next to the moon.

Your fingernail and the moon are about the same size.

Try it again when the moon is high, and you will get the same result.

The moon near the horizon is a little farther away from you.

So it is really a tiny bit smaller, not bigger!

Then why does it look so big?

People have wondered about this for more than 2,000 years.

Scientists still do not have one clear answer.

One idea is about distance.

Our brain seems to feel that the sky near the horizon is farther away than the sky above us.

If two things look the same size, the one that seems farther away must be bigger.

So the brain makes the low moon look bigger.

Another idea is about the things around the moon.

Next to small houses and trees, the moon may look very large.

But astronauts in space also see the moon illusion, and there are no houses or trees up there.

Bend over and look at the big moon between your legs.

It will not look so big anymore.

Your brain did the trick.