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How does a lunar eclipse happen?

SunEarthEarth's shadowMoon enters the shadow

A lunar eclipse happens when the Earth moves between the Sun and the Moon and casts its shadow on the Moon.

A lunar eclipse is a very special thing to see in the night sky. When the Sun, Earth and Moon line up in a straight row, the Earth's shadow falls on the Moon. This makes the Moon look dark or red to us.

This can only happen on a full moon night, because that is when the Moon can pass right behind the Earth. But it does not happen every full moon, because the Moon's path is a little tilted.

During a lunar eclipse, the Moon sometimes turns orange or red. This is called a 'blood moon'. It happens because sunlight passes through Earth's atmosphere before it reaches the Moon.

Unlike a solar eclipse, you can safely watch a lunar eclipse with just your eyes, from anywhere on Earth where it is night. You do not need any special glasses.

Quick facts

A lunar eclipse happens when Earth's shadow falls on the Moon.
A lunar eclipse can only happen on a full moon night.
During an eclipse, the Moon can turn red or orange.
You can watch a lunar eclipse with just your eyes, no glasses needed.
An eclipse happens when the Sun, Earth and Moon line up in a straight row.
Because the Moon's path is tilted, an eclipse does not happen every full moon.

Check what you remember

3 questions — all of them come from the quick facts above. There is no score and no wrong turn.

1. When does a lunar eclipse happen?

2. What colour can the Moon turn during a lunar eclipse?

3. What do you need to watch a lunar eclipse?

Where this comes from

1 spaceplace.nasa.gov 90/100
NASA Space Place
NASA's fun website made for children that explains space events in a simple way.
2 tr.wikipedia.org 85/100
Lunar Eclipse - Wikipedia
An encyclopedia page that shows with pictures how a lunar eclipse happens.
3 britannica.com 80/100
Lunar Eclipse - Britannica
A trusted encyclopedia page that explains lunar eclipses in a clear, scientific way.

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Earth's Shadow

Earth leaves a shadow in space, just like you make a shadow on a sunny day. When the Moon moves into this shadow, the eclipse begins.

🔴

The Red Moon Colour

During an eclipse, the Moon can look bright red. This happens because Earth's atmosphere filters the sunlight and sends the red colour onto the Moon.

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Full Moon and Orbit

A lunar eclipse can only happen on a full moon night. But because the Moon's path is tilted, it does not happen every full moon.

☀️

How It Differs from a Solar Eclipse

In a solar eclipse, the Moon moves between the Sun and the Earth. In a lunar eclipse, the Earth moves between the Sun and the Moon.

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