The longest lunar eclipse of the century to give the United Kingdom a rare celestial thrill | Science

Great Britain will witness a spectacular and rare celestial spectacle this week. At dusk on Friday, the full moon will rise and be colored a deep red. The nation will then experience a blood moon or, according to astronomers, a total lunar eclipse.

And this week promises to be special because it will be the most lasting total lunar eclipse of the 21st century. After ascending to the southeast – around 20:50 in London – the lunar eclipse will continue until Saturday morning. "If time permits, it should give a special advantage on Friday night," said Sheila Kanani of the Royal Astronomical Society

. Their dark red color has generally been regarded as an omen of terrible events. The Book of Joel in the Hebrew Bible warns that "the sun will be turned into darkness, and the moon into blood, before the great and terrible day of the Lord".

Today scientists have a more prosaic explanation of the crimson moon transformation. It is caused when the moon passes through the shadow of the Earth. However, its disk does not become completely dark because some sunlight – mainly the longest wavelength, the red end of the spectrum – crosses our atmosphere and bends around the perimeter of our planet for some time. She falls on the surface of the moon. Indeed, it is the sunrise and sunset light on the Earth that will give the moon its red glow Friday

Unlike total solar eclipses, which occur when the moon's disk passes in front of the sun and completely erase the sunlight. for a few minutes, a blood moon is a pretty quiet affair. "It will last several hours – when you have a real feeling of the Earth and the moon moving in space," said astronomer Tom Kerss, of the Royal Observatory of Greenwich, who plans to broadcast live footage of the event on Friday. "You have a real sense of movement of the solar system – and it's in itself a really dramatic experience."

For good measure, it is not necessary to wear glasses or filters to observe a blood moon as is necessary with solar eclipses. "It's safe to look at the naked eye," said Kerss. "You could use a telescope but, to be honest, it will be just as dramatic to watch it without help as the red moon slowly climbs into the sky over Britain and the Earth's shadow goes from its surface. "