By Dr David Whitehouse
BBC News Online science editor
Skywatchers are preparing themselves for a total eclipse of the Moon on Thursday night into Friday morning.
The Moon turns a beautiful shade of red
It will be visible from much of Europe, Africa and the Americas.
The slow and subdued nature of lunar eclipses makes them less dramatic than solar eclipses. Scientifically they are also less important.
From the UK, the eclipse will occur in the early hours of Friday morning, when the Moon is low over the southern horizon.
At the start of the eclipse, the satellite is 17 degrees above the horizon. It gets lower in the southern sky as the event progresses. By mid-eclipse, at 0440 BST (0340 GMT), it is just five degrees above the horizon.
Serenity and fertility
Lunar eclipses are an enchanting spectacle of nature, delightfully reminding us of the cycles and rhythms of the cosmos, of which we are only spectators.
TOTAL LUNAR ECLIPSE
Occurs when Moon passes into Earth's shadow
Penumbra: Region where Earth blocks some (but not all) Sun rays
Umbra: Zone where Earth blocks all direct sunlight - total eclipse
Although not as spectacular as when the Moon crosses the face of the Sun, lunar eclipses have a beauty and grandeur of their own.
Thomas Hardy said the movement of the Earth's shadow over the Moon had an "imperturbable serenity".
This week's event lasts just over five hours. One thing to watch out for is the colour of the Moon as it moves into the Earth's shadow.
During a total lunar eclipse the only light that can reach the Moon's surface has been refracted through our planet's atmosphere on the limb of the Earth as seen from the Moon.
Stuff of myth
The refracted light is red. If it were possible to look back at the Earth during a lunar eclipse then the rim of the Earth would appear a glowing red.
WHERE TO SEE IT
South America and eastern North America get best view
Dust and cloud in Earth's atmosphere affects Moon colour
Telescope is useful but total eclipse is viewable with naked eye
This colour effect is the stuff of myth and legend. An account in 331 BC said: "...all her light was sullied and suffused with the hue of blood."
Some ancients called it "the time of the blood of the Great Mother's wisdom", linking the Moon's colour with menstruation. This was a natural thing to do given the link between the length of the month and human fertility.
In 1503, Christopher Columbus, stranded in the Caribbean, used a lunar eclipse he knew would take place to impress the natives and secure respect and fear, as well as a regular supply of food.