On Tuesday night a blood moon will grace our skies, causing our celestial neighbour to glow a spectacular reddish colour.

It’s a fascination and phenomenon that has transfixed people for generations, but what is a blood moon?

What is a blood moon?

A blood moon, or a total lunar eclipse, is when the Moon passes into Earth’s shadow.

During a total lunar eclipse, the Moon and the Sun are on opposite sides of Earth.

Dr Brad Tucker, an astrophysicist from The Australian National University, told The New Daily that the shadow cast by the Earth is what causes the Moon’s surface to turn red.

Earth’s shadow is categorised into two parts: The umbra, the innermost part of the shadow where direct light from the Sun is completely blocked, and the penumbra, the outermost part of the shadow where the light is partially blocked.

“While the Earth casts a shadow into space, a little bit of sunlight skims through the Earth’s atmosphere and into space,” Dr Tucker said.

“Just as sunrise and sunset are an orange or reddish colour, so is this light that skims through the Earth’s atmosphere and out into space.

“When you look at the Moon during the total lunar eclipse, you are seeing the sunrise and sunset of the Earth lighting up the Moon.”

According to NASA, the more dust or clouds in Earth’s atmosphere during the total lunar eclipse, the redder the Moon will appear.

Many cultures, including some Indigenous Australian communities, saw this as a bad omen and associated it with death or blood.

Credit: NASA/SDO; NASA; ESA/Hubble & NASA, R. Cohen; Getty; TND – Inspiration ABC

When can you see a blood moon?

The phase when the Moon is completely covered in shadow is called totality.

This stage lasts an hour and a half and is the best time to view a blood moon.

Stargazers on the east coast will see the totality for about an hour and a half.

It’s a family-friendly event this year, with the partial lunar eclipse beginning before 9pm.

On the west coast, the totality will last about an hour because the Moon will already be in the shadow before it rises. This means the Moon will rise as a blood moon on the eastern horizon.

All of Australia will be able to see the blood moon and it will also be visible in New Zealand, the Americas and parts of Asia.

Here are the times by state and territory.

Is it safe to look at a lunar eclipse?

Yes.

No special glasses or equipment is required, unlike solar eclipses (which occur during the daytime).

“You don’t need any special equipment, you don’t need a telescope or protection, you just need your eyes,” Dr Tucker told TND.

“You don’t even need to be in a very dark area, like some other things that we look out in space, just going out at home, looking through the window, even if you’re in the right orientation, means that you will have a great view of it without a lot of extra equipment.”

President Donald Trump points skyward before donning protective glasses to view the solar eclipse in August 2017. Photo: AAP

When is the next blood moon?

In a regular calendar year, the Earth usually experiences two total lunar eclipses – one towards the beginning and one towards the end of the year.

But Tuesday’s eclipse will be the last in totality until 2025 because of the position of Earth and the Moon.

“It’s not the sort of thing that if you don’t see it, you’ll never see it again,” Dr Tucker said.

“But you’ll have to wait a few years. And also, we can’t always guarantee it at a nice, family-friendly time. Very rarely does an eclipse occur right after sunset in the early evening.”