You might have noticed the almost full-Moon yesterday afternoon as you merrily digested your Christmas roast. This is the Cold Moon, and as well as being the last full Moon of the year, it’s also the first full Moon after the winter solstice.
But when is the best time to see the full Christmas Moon from the UK? Which constellation will the Cold Moon be in? Here’s everything you need to know (and more).
And if you fancy taking up a new hobby in the New Year – it’s never too late to dive into astronomy. From learning how to differentiate between constellations, getting to grips with the celestial sphere, or knowing your planet from your star; there’s something for everyone.
But where to start? Just for you, we’ve put together a handy astronomy for beginner’s guide, packed full of expert stargazing tips to help you out. Or perhaps you’d like to take up photography? Veteran astrophotographer Pete Lawrence has put together a practical guide on how to take great pictures of the Moon, whether you’re a beginner using a smartphone, or you have more kit at your disposal.
When can I see the Cold Moon 2023?
The Cold Moon will be visible tonight, 26 December 2023 in the UK, US and around the world. Peak illumination for the Christmas Cold Moon will be when the Moon is high overhead. And if it’s a cold night with enough ice in the air, we may also be treated to an ethereal Moon halo.
When viewed from London, the Cold Moon will rise in the northeast at 2:52pm GMT on 26 December 2023, and set in the northwest at 9:07am 27 December, the next morning. The Moon will reach peak illumination at 00:33am, just after midnight on 27 December.
From New York, the Holiday Cold Moon will rise in the northeast at 6pm EST on 26 December 2023, and set in the northwest at 8:13am on 27 December.
From Seattle, the Cold Moon will rise in the northeast at 3:46pm PST on 26 December 2023, and set in the northwest at 9:07am on 27 December.
What is the best time to see the Cold Moon?
The Cold Moon in 2023 will reach peak illumination at 00:33am GMT in the early hours of 27 December 2023. At this time, the Moon will be high overhead, situated above the winter constellation Orion. At this time, the Moon will be around 385,930km away from the Earth.
If the evening skies are clear, the best time to see the full Christmas Moon will be soon after dark on Boxing Day, 26 December.
The Moon will rise at around 2:52pm GMT (as seen from London), and the Sun will set around an hour later around 3:56pm. By 5pm, the Moon will still be relatively low on the horizon, just as Orion is starting to peek over the horizon.
Although peak illumination will occur just after midnight, looking out in the early evening will reward you with a pretty view of the Moon, hovering just above local landmarks in your area. We’ll also have the benefit of the Moon Illusion at this time, where the Moon looks larger when it’s nearer the horizon.
The Moon will set at 9:07am on the morning of 27 December 2023, with the Sun rising around one hour earlier, at 8:05am.
Why is it called a Cold Moon?
Around the world, many of the names for the December full Moon relate to temperature. With astronomical winter starting on 22 December 2023, and meteorological winter already well underway having started on 1 December, the start of the cold season is officially here. The roads have been gritted, you’ve scraped ice off your car and you've felt the bite as you resist turning the heating up a notch.
So it’s perhaps not surprising that the name Cold Moon is given to the full Moon in December. (however, January and February are, on average, technically the coldest months in the UK.)
Other names for the December full Moon include Long Night Moon, and if it falls before Christmas – the Moon Before Yule.
What constellation will the Moon be in?
On Christmas Day, the Moon passed 9.4 degrees north of Aldebaran in Taurus, by 28 December will have moved to be 1.7 degrees south of Pollux, the brightest star in the constellation Gemini. Later in the month on New Year’s Eve, it will be 3.8 degrees north of the Regulus, the brightest star in the constellation Leo the Lion.
On 26 and 27 December, the Moon is between Gemini (below) and Auriga (above), and it’s the first full Moon after the winter solstice.
Latin for ‘the charioteer’, Auriga is somewhat of a lesser-known constellation, but its five-sided pentagonal shape contains the sixth brightest ‘star’ in the night sky, Capella, the ‘goat star’. Although it may appear as a single star to the naked eye, Capella is actually four stars; two large binary stars and two dwarf stars.
Is the Cold Moon in 2023 a supermoon?
No, sadly the Cold Moon in 2023 is not a supermoon.
A supermoon is an unofficial term that’s caught on in recent years for when the Moon is situated 360,000km (or less) away from Earth in its orbital path. Because the Moon is in an elliptical orbit around the Earth, its distance from us fluctuates throughout the year and some full Moons appear larger, as they are closer to us.
A supermoon occurs when the Moon is at its closest point to Earth along this elliptical orbit (this point is called perigee). When the Moon reaches perigee at the same time as a full Moon, it appears larger and brighter than an average full Moon, thus we have a supermoon. Although not as catchy as the commonly used ‘supermoon’, the technical term for a supermoon is a perigee-syzygy Moon.
We'll often see two or three full supermoons in a row, giving us a 'supermoon season'.
The opposite is also true. When the full Moon is at the furthest point away from Earth along this orbit – this point is called the apogee – the Moon appears smaller, and we get a 'micromoon'.
The supermoons in 2023 were:
- July – the Buck Moon: 361,934 km (224,895 miles)
- August – the Sturgeon Moon: 357,530 km (222,158 miles)
- August – a rare Blue Moon: 357,344 km (222,043 miles)
- September – the Harvest Moon: 361,552 km (224,658 miles)
The next supermoon will be 18 September 2024, the Harvest Moon.
What causes a full Moon?
A full Moon forms part of the lunar cycle and occurs when the Moon is fully illuminated by the Sun. This happens when the Earth is positioned directly between the Sun and the Moon. We usually have 12 full Moons in one calendar year, although in some years we can have 13, with the ‘extra’ Moon being known as a Blue Moon. The most recent Blue Moon was in August 2023.
When the Moon is full, it’s located precisely 180 degrees opposite the Sun in ecliptic longitude. In other words, that the Moon, Earth, and Sun are in a straight-line configuration.
Technically, the Moon is only 'full' for an instant (called syzygy), but it will appear full for the entire night. To our eyes, the Moon will also seem to be full for both nights on either side of the Cold Moon.
The Moon takes 29.53 days (29 days, 12 hours, 44 minutes, and 3 seconds) to complete one lunar cycle. That means we get a full Moon every 29.53 days. This figure is calculated by the time it takes the Moon to orbit the Earth once, as measured from new Moon to new Moon. You may also hear this being referred to as one synodic month.
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