A "supermoon" is to light up the night sky alongside this year's Perseid meteor shower in one of the most dramatic and anticipated astronomical events of the year.
The Perseids will appear with a "supermoon" that will be up to 14% bigger and 30% brighter than full moons through the rest of the year.The moon will become full on Sunday, just two days before the meteor shower reaches its peak.
The moon will also have reached the point known as "perigee" in its orbit, where it is closest to the Earth.
It is also common to see more than 100 of the meteors an hour during the second week in August, given a dark, clear sky.
But for Dr Bill Cooke from the American space agency Nasa's Meteoroid Environment Office, this is bad news.
Dr Cooke added that the Perseids were also "rich in fireballs as bright as Jupiter or Venus" that would remain visible despite the moon's glare.A study conducted by his team since 2008 has shown the Perseids to be the undisputed "fireball champion" of meteor showers.
He pointed out that at this time of year the moon is relatively close to the horizon, leaving much of the sky dark.
Tony Markham, director of the Society for Popular Astronomy's meteor section, also urged skywatchers to stay optimistic.
Mr Markham also suggested looking at an area of sky 20 to 30 degrees away from the Perseid radiant - the spot near the constellation of Perseus that the meteors appear to fly out from.
Every 133 years, comet Swift-Tuttle swings through the inner Solar System leaving behind a trail of dust.When the Earth passes through, the dust cloud particles hit the atmosphere at 140,000 mph and burn up in streaking flashes of light, creating the spectacle known as the Perseids.
The best time to see the meteors is between Saturday and Wednesday, with activity peaking on Tuesday.An unusually bright full "supermoon" was also seen on July 12, and another is due to appear on September 9.But the supermoon of Sunday promises to be the most dramatic since this is when the moon will be at its closest point to the Earth all year.
At perigee, the moon is around 31,000 miles closer than when it is furthest away from the Earth.Supermoons occur relatively often, every 13 months and 18 days, but are not always noticed because of clouds or poor weather.