The eclipse will occur at 2018 GMT when the Earth's shadow begins to creep over the Moon – a stage known as the penumbral eclipse, reported Agence France-Presse (AFP).

The Moon will recede entirely some six hours later at 02:23 GMT on Sunday.

Total lunar eclipses occur when the Sun, the Earth and the Moon are all in alignment and the Moon travels into the broad cone of shadow cast by the Earth.

The Moon does not become invisible, though, because there is still residual sunlight that is deflected towards it by the Earth's atmosphere, most of which is light in the red part of the spectrum.

That causes the Moon to appear as a dark color, usually a coppery red, orange or even brown.

People in Europe, the Middle East and Africa will have a front-and-center view of the lunar eclipse in a late-night sky, with the zenith occurring at 23:21 GMT.

On the east coast of North America, the Moon will already be eclipsed when it rises at around sunset.

In Asia, early risers will get a glimpse of the lunar blackout as the Moon sets.

Total lunar eclipses normally occur roughly every couple of years.

The next total lunar eclipse will take place on August 28.

The last lunar eclipse took place on October 28, 2004.

Spectacular

Astronomers expect Saturday's lunar eclipse to be the "best in years"

"If the clouds stay away, it will be fascinating to watch the Moon's graceful movement through the shadow of the Earth," Robin Scagell, from the Society for Popular Astronomy, told the BBC News Online.

Robert Massey, spokesman for the UK's Royal Astronomical Society, agrees.

"They are beautiful events," he said.

"They have a really romantic feel to them as you look up because the Moon, which is normally pearly white, takes on this reddish color," he said, calling on millions of people around the world to witness the "spectacular" event.

"It is like Mars suddenly coming a thousand times closer and just hanging there in the sky above you."

Massey said it is totally safe for people to observe, adding that no protective filters were needed because the Moon would actually be less bright than during a normal full moon.

"It is not like a solar eclipse where you get to see the outer atmosphere of the sun," he said.

"There were some people in the past who measured how different parts of the Moon cooled down as the Earth's shadow passed over it, but I doubt much of that work is going on now."

Total solar eclipses happen when the Moon crosses between the Earth and the Sun.