Moon of Blood: All you need to know about this week's lunar eclipse | Science

The longest lunar eclipse of the century (up to now) will take place on Friday night and Saturday morning, as the moon is totally overshadowed by the Earth for one hour and 43 minutes. Meanwhile, people around the world will be able to see a "blood moon" because the Earth's satellite turns red

What's a Blood Moon?

A "moon of blood" is a name given to the moon during a lunar eclipse. A lunar eclipse occurs when the Earth passes between the sun and the moon, casting the moon in the shade.

Unlike a solar eclipse, when the moon passes between the Earth and the sun, blocking sunlight, the moon is not "darkened" during an eclipse, but seems to turn red

"If Earth was a big smooth ball without atmosphere that would be the end of the subject, it would become dark, as with a new moon, "said Chris Tinney, professor at the physics department of New South University. Wales. "But because there is scattered light in the Earth's atmosphere, part of the sunlight bounces off the edge of the Earth."

Because the blue and violet wavelengths are more scattered than more red wavelengths reach the moon, making the moon appear red.

How rare is it?

Lunar eclipses are less frequent than solar eclipses, with a maximum of three eclipses in a given location per year, although in some years there is none. However, each lunar eclipse is visible from more than half of the Earth.

If this eclipse is rare, it is because it will last so long. The moon will be in the shadow of the Earth for four hours and totally eclipsed for one hour and 43 minutes, which is just below the theoretical limit of a lunar eclipse (one hour and 47 minutes). The eclipse will last so long on Friday night because the moon will cross the center of the Earth's shadow.

Where and when can I see him?

The best view of the eclipse will be from East Africa, the Middle East, across India and the most westerly tip of China. But there are still reasonable opinions for people in the rest of Africa, Europe, in other parts of Asia, in Australia and at the eastern end of the world. South America.

North America and Greenland seem to be the only places that will be missed completely

In Australia: the moon will begin to turn red at 4:30 am on Saturday morning, with the total eclipse occurring between 5:30 and 6:30, before the moon goes down at 6:55. The moon will be close to the horizon, so be sure to look west-southwest.

In the United Kingdom: The total eclipse will be visible between 21:20 on Friday, with the moon visible to the southeast, until 22:13

In East Africa: l & # 39; 39, partial eclipse will begin at 21:30 EDT, with the moon completely red between 22:30 and 12:13. This region will have one of the best views of the eclipse

In India: The total eclipse will start at 1am, ending at 2:43 am

Tips for watching the moon of blood

"The best place to see this is in the country far from the lights," said Tinney. "If you live in [a city] then there is a lot of light pollution from the night sky, so the contrast between the moon and the sky will not be so big. "

One can watch the moon safely during an eclipse.

Timeanddate.com has a good eclipse tracker, which allows you to enter your position and find the best time to see the eclipse.

For those in areas that will miss the blood moon, the Royal Observatory of Greenwich plans to broadcast images live from the event.