How Big Are the Sun and Moon, and How Far Away Are They? — For Kids

The Sun and the Moon — Elementary

The short answer

The Moon is much smaller than the Sun.

But the Moon is much closer to us.

So the Sun and the Moon look about the same size in the sky.

How far away is the Moon?

The Moon is an average of 238,855 miles away from Earth.

That is 384,400 kilometers away.

Picture 30 Earths in a row.

That row is about how far the Moon is.

Drawings can make the Moon look close to Earth.

Do not be fooled.

It is really far away.

The Moon does not stay the same distance away

The Moon goes around Earth.

That path is called its orbit.

The orbit is not a perfect circle.

So the Moon is not always the same distance away.

At its farthest, the Moon is 251,903 miles away.

That is almost 32 Earths in a row.

At its closest, the Moon is 225,309 miles away.

That is between 28 and 29 Earths in a row.

How big is the Moon?

The Moon is about a quarter the size of Earth.

That means Earth is much bigger than the Moon.

How far away is the Sun?

The Sun is about 93 million miles away from Earth.

The Sun is about 400 times farther away than the Moon is.

First picture the trip to the Moon.

Then picture 400 of those trips in a row.

That is about how far the Sun is.

How big is the Sun?

The Sun is about 100 times wider than Earth.

Picture 100 Earths in a row across the Sun.

The Moon is about 400 times smaller than the Sun.

Why do they look the same size?

The Moon is about 400 times smaller than the Sun.

But the Moon is also about 400 times closer to Earth.

Things that are closer look bigger.

Things that are far away look smaller.

So the small, close Moon and the big, far Sun look about the same size in the sky.

That is how the Moon can cover the Sun in a total eclipse.

The Moon is slowly moving away

The Moon’s orbit grows about 1.5 inches larger every year.

So the Moon is very slowly moving farther away.

The scale ladder

Start with sizes.

The Moon is about a quarter the size of Earth.

The Sun is about 100 times wider than Earth.

The Sun is about 400 times wider than the Moon.

Now do distances.

The Moon is 30 Earths away.

The Sun is about 400 times farther away than the Moon.

The Sun and the Moon — Middle

The short answer

The Moon is about 400 times smaller than the Sun, but it is also about 400 times closer to Earth.

Those two 400s balance out, so from Earth the Moon and the Sun appear to be roughly the same size in the sky.

How far away is the Moon?

The Moon is an average of 238,855 miles (384,400 km) away from Earth.

Another way to picture that distance is 30 Earths in a row.

Drawings of Earth and the Moon often make them look really close together, but do not be fooled: they are really far apart.

We can see the Moon well without a telescope, which makes it seem close, but it is farther away than most people realize.

Why we say “average” distance

The Moon is not always the same distance away from Earth, because its orbit is not a perfect circle.

When the Moon is farthest away, it is 251,903 miles away — almost 32 Earths in a row.

When it is closest, the Moon is 225,309 miles away — between 28 and 29 Earths in a row.

The average of 238,855 miles sits between those two ends of its orbit.

How big is the Moon?

The Moon is roughly a quarter the size of Earth.

So on a size ladder, the Moon is the small first step, and Earth is much bigger.

How far away and how big is the Sun?

The Sun is approximately 93 million miles away from Earth.

That is 400 times farther than the distance between Earth and the Moon.

The Sun is about 100 times wider than Earth.

Put the size steps together: the Moon is about a quarter the size of Earth, Earth is about 100 times narrower than the Sun, and so the Moon ends up about 400 times smaller than the Sun.

Why the Moon can cover the Sun

When objects are closer to us, they appear to be bigger than objects that are far away.

Even though the Moon is 400 times smaller than the Sun, it is also about 400 times closer to Earth than the Sun is.

That means that from Earth, the Moon and the Sun appear to be roughly the same size in the sky.

So when the Moon passes between Earth and the Sun during a total solar eclipse, the Moon appears to completely cover up the light from the Sun.

A distance that is still growing

The Moon’s orbit is changing: it grows about 1.5 inches larger every year.

As the Moon’s orbit takes it farther and farther away from Earth, the Moon will appear smaller and smaller in our sky.

The scale ladder, in order

For size: Moon, at about a quarter the size of Earth; then Earth; then the Sun, at about 100 times wider than Earth and about 400 times wider than the Moon.

For distance: the Moon, at an average of 30 Earths away; then the Sun, at about 93 million miles away — about 400 times farther than the Moon.