Get the telescope out, because tonight the moon will be closer to Earth than it has been for the last 19 years.
Experts have said there will be clear skies for the so-called Supermoon - which describes a full moon that is at more than 90% of its closest position to Earth.
The last time it was so near - called a lunar perigee - was on January 20, 1992.
At its furthest - a lunar apogee - the Moon can be almost 250,000 miles away.
At 6.10pm tonight it will be exactly 220,625 miles away from Britain - 625 miles closer than a month ago. It will appear 14% bigger and 30% brighter than at its most distant.
The effect will be the most impressive when the Moon is close to the horizon, sitting atop the hills and houses.
When it gets high in the sky it will be hard to detect any size difference because there will be nothing for the eye to compare it with.
Robert Massey of the Royal Astronomical Society said: 'Tonight the Moon will be unusually close and a little brighter, but the visual effect of it being closer to the Earth is unlikely to be noticed by the human eye.'
Experts say that it will cause the highest tidal range and could cause flooding of coastal areas.
Dr Massey - who rubbished recent claims that the Japanese earthquake and tsunami were connected to the Moon's movements - added: 'I would tell people not to expect a wow factor, but it is nice to go and have a look.'
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