A lunar eclipse happens when the Earth moves directly between the Sun and the Moon, blocking sunlight from reaching the Moon. Instead of the Moon shining brightly in the night sky, it gets dark and sometimes turns a reddish color.
Sunlight usually makes the Moon shine – The Moon doesn’t produce its own light; it reflects sunlight.
Earth casts a shadow – When the Earth gets in the way of the Sun’s light, it casts a shadow on the Moon.
Moon moves into Earth's shadow – The Moon passes through this shadow, causing the eclipse.
Total Lunar Eclipse – The entire Moon moves into Earth’s shadow and turns red. This happens because Earth’s atmosphere bends sunlight around the planet, filtering out blue light and letting only red and orange light reach the Moon (this is why it’s sometimes called a “Blood Moon”).
Partial Lunar Eclipse – Only part of the Moon moves into Earth's shadow, so a piece of it remains bright.
Penumbral Lunar Eclipse – The Moon moves through the outer part of Earth's shadow (the penumbra), making it look slightly dim, but not completely dark.
Lunar eclipses only happen during a full moon, but not every full moon has an eclipse because the Moon’s orbit is slightly tilted compared to Earth’s orbit around the Sun. You can see a total lunar eclipse from anywhere on Earth where the Moon is above the horizon when it happens.
Unlike a solar eclipse, which is dangerous to look at without protection, a lunar eclipse is completely safe to watch with your eyes, binoculars, or a telescope!