Skygazers will be treated to a bigger and brighter moon this weekend as it moves closer to Earth.
December’s full moon – traditionally known as the Cold Moon – will appear 14% bigger and 30% brighter than usual on Sunday.
Tom Kerss, an astronomer at Royal Observatory Greenwich, said the exact moment of full moon – when the moon sits opposite the sun in the sky – will take place at 3:47pm GMT on Sunday, with moonrise occurring about 45 minutes later.
He added: “This year’s Cold Moon is closer to us than the average full moon this year; close enough to qualify as a ‘supermoon’ according to the widely accepted definition.
“The moon will reach its highest point above the horizon at midnight local time. This is when, weather permitting, it will appear at its clearest and brightest.”
The moon has a slightly elliptical orbit – it does not move round the Earth in a perfect circle.
At some points the moon is about 5% closer to Earth than average, known as perigee, and at others 5% further away, known as apogee.
The full moon will be 222,761 miles from Earth, closer than its average 238,900 miles.
Mr Kerss said: “During moonrise and moonset, you might think the moon looks unusually large, but this is an illusion created in the mind when it appears close to the horizon.
“In fact, the change in the moon’s apparent size throughout its orbit is imperceptible to the unaided eye.
“Nevertheless, the ‘moon illusion’ can be a dramatic effect, and with the moon rising so early, there will be ample opportunities to see its apparently huge face juxtaposed with the eastern skyline.”
For those wanting to see the Earth’s natural satellite in greater detail, Mr Kerss advises using a binocular or a telescope and observing the dark maria – large and dark basaltic plains on the surface of the moon.
He said: “It’s perfectly safe to look directly at the full moon, even with a telescope or binoculars.
“You can see many of the moon’s larger features, although at full moon its surface looks rather flat, since we don’t see any shadows cast across it until its night side begins to creep into view.
“However it is possible to see the dark maria (seas) in stark contrast to the brilliant highlights of the full moon if you allow your eyes to adjust and pick out these ancient volcanic flood plains, once filled with lava.”
The first supermoon of the year was visible on January 12, and the second one occurred more recently on November 3.