A total solar eclipse happens when the Moon passes between the Sun and Earth. It blocks the face of the Sun. During this eclipse, the daytime sky gets dark. It looks as if it were dawn or dusk. A solar eclipse happens at the new moon. That is when the Moon moves between Earth and the Sun.

You may have heard that the Moon is too small to cover the Sun. In fact, the Sun is about 400 times wider than the Moon. But it is also about 400 times farther away. So they look about the same size in the sky. On Earth, the narrow line where a total eclipse can be seen is called the path of totality.

Not every eclipse looks the same. There are four types of solar eclipse: total, partial, hybrid and annular. In a partial eclipse, the Moon covers only part of the Sun. In an annular eclipse the Moon is too far from Earth to cover the whole Sun. So it looks smaller than the Sun. An eclipse can be seen from only a small part of Earth at a time.

The Moon's shadow has a dark center called the umbra. It has a lighter outer part called the penumbra. The Moon's orbit around Earth is tilted by about five degrees. The Moon has eclipses too. In a lunar eclipse, Earth's shadow falls on the Moon. A lunar eclipse happens at the full moon. The Moon in a total lunar eclipse often looks a dull red or orange.

Why do scientists care about eclipses? Eclipses are very useful to scientists, as well as beautiful. In a total eclipse, the Moon blocks the face of the Sun. Here is one thing it shows. The corona is the Sun's outer atmosphere. We cannot normally see it because the Sun's bright surface is in the way. But it shows in a total eclipse.

Never look straight at the Sun without proper eye protection. This is true even during a partial eclipse. Regular sunglasses are not safe for looking at the Sun. Eclipse glasses are special glasses. They are made for looking at the Sun safely. A grown-up can give you a pair. A pinhole projector lets you watch an eclipse as a shadow picture. You do not look at the Sun through the hole.

Words to know

• umbra: dark center
• penumbra: lighter outer part
• corona: Sun's outer atmosphere
• annular: Moon looks smaller

The short version

A total solar eclipse happens when the Moon passes between the Sun and Earth and blocks the face of the Sun, and the daytime sky gets dark. A lunar eclipse happens when Earth's shadow falls on the Moon. Regular sunglasses are not safe for looking at the Sun. Eclipse glasses are made for it.

Quick facts

• The Sun is about 400 times wider than the Moon but also about 400 times farther away, so they look about the same size in the sky.
• There are four types of solar eclipse: total, partial, hybrid and annular.
• A solar eclipse happens at the new moon, and a lunar eclipse happens at the full moon.
• The Moon in a total lunar eclipse often looks a dull red or orange.