Astronomy enthusiasts are encouraged to keep their eyes peeled this month for longest Full Moon of the year on Saturday, December 22. As a bonus, the so-called December Frost Moon will peak on the day following the Winter Solstice – the longest night of the year. The Moon will appear full for about three days surrounding its peak phase, giving stargazers a great opportunity to see it light up the night. According to NASA, the Moon will reach full illumination around 5.49pm GMT (UTC) in the afternoon.
In the UK, this means the Moon will be perfectly visible once the Sun sets after 3.53pm GMT.
And Weather Network meteorologist Scott Sutherland said the Full Moon phase is going to last a total of 15 hours and 32 minutes this month.
He said: “That’s the longest Full Moon of the entire year.
“We haven’t seen a Full Moon last that long since December 2010, when it was in the sky for 15 hours and 54 minutes on the 20th and 21st.”
When seen from London, the nearly full Moon will set at 7.24am GMT in the morning and reappear over the horizon at 4pm GMT.
Full Moon 2018: The December Full Moon will be the longest Full Moon of the year
You will be able to track the Full Moon’s journey across the night sky until it sets the following day at 8.33am GMT.
That’s the longest Full Moon of the entire year
In New York, US, the Moon sets at 6.55am EST and rises at 4.47pm EST before it vanishes again on the following day at 8am EST.
On the other side of the Pacific Ocean, in Japan, the Moon sets on the morning of December 22 at 6.54am JST and rises at 5.10pm JST.
In Mumbai, India, the moon will set at 6.24am IST and rise again at 5.54pm IST.
How long does the Full Moon phase last?
It is hard to pinpoint just how long a Full Moon lasts, or any lunar phase for that matter, because each phase only appears for a brief moment.
But astronomers can note how long a particular phase will appear to last in the night sky.
NASA explained: “Well, the phases are just names we give to certain points along the Moon’s smooth path around Earth.
“Technically, each phase, just like the one called a New Moon, when the Moon is exactly between Earth and the Sun, lasts only a brief instant.
Full Moon 2018: The December Full Moon is known as the Frost Moon
Full Moon 2018: The Full Moon will peak at 5.419pm GMT
“But to our eyes, a New Moon can last for a few days, representing the time that the Moon appears in the sky too near the Sun’s position for us to see it at all.”
Overall, it takes the Moon just short of a month to complete its lunar cycle – about 29 days.
During this cycle, the Moon goes through the New Moon, First Quarter Moon, Full Moon and Third Quarter Moon phases.
The phases are all predetermined by the amount of sunlight falling on the side of the Moon facing the Earth at all times.
NASA added: “It isn’t just the Moon that appears to have phases. The planets also have phases.
“For example, the orbit of Venus is inside the orbit of Earth.
“When Venus is in the part of its orbit between Earth and the Sun, we can’t even see it, because its sunlit side will be away from us. This position is similar to the New Moon phase.
“As Venus progresses around the Sun, more and more of its illuminated side is visible to us on Earth.
“When Venus is on the far side of the Sun, we will see its Full Phase.”