Mood swings, bad sleep and supernatural phenomena. A lot has been blamed on the arrival of a full moon. But whether you believe in its celestial effects or not, the moon’s majesty is undeniable – only more so when a supermoon is floating over London skies.
Lunar fans should count themselves lucky. There are currently four supermoons lined up in as many months, with the next one occurring on August 19, 2024 (also known as the Sturgeon Moon). It’s also a seasonal Blue Moon – the third of four full moons in an astronomical season. But we don’t want to get too bogged down in definitions…
What is a supermoon?
A supermoon is a full moon that is within 90% of its closest approach to Earth – a point known as ‘perigee’ (356,445km away). Anytime the moon is less than 360,000km away from Earth, it’s considered ‘super’. The furthest away (406,712km) is known as ‘apogee’ and is when we get a ‘micromoon’.
When the moon is this close, it appears up to 14% larger and 30% brighter than when at apogee. In reality, it’ll be only 7% larger and 15% brighter than your average full moon. And while these may only sound like small numbers, they can make a huge difference to their appearance in the sky.
We haven’t seen a supermoon since the Harvest Moon on September 29, 2023. But after the arrival of the supermoon on August 19, three more will occur on September 18, October 17 and November 15. We should insert some ‘like buses…’ joke here, but I’m sure you didn’t come here to hear my lame attempts at humour.
Why so many in a row?
With only 12 to 13 full moons a year, you might think it’s a little odd to get four in a row. Especially after we haven’t had a supermoon in almost a year. But supermoons usually occur every 14 lunar months with two to five in a row. Three in a row is the most common, but hang around until 2029 to witness five supermoons, and again for the next four years!
When is the best time to see a supermoon?
Whether it’s a supermoon or not, a full moon will always appear brightest after moonrise and before moonset. This is the time when the moon is closest to the horizon and, through something called the ‘Moon illusion’, it appears much larger than it does high in the sky (you might want to get out from among the tall London buildings).
There are a few theories as to why this happens – from atmospheric refraction to its relative size to its surroundings in the sky, and the often debunked position of the eyes in the head. It’s been argued since the heyday of the Roman Empire and we’re not solving it here, sorry, but The Moon Illusion (2013), edited by Hershenson, delves deeper into the subject if you’re interested.
On Monday, August 19, 2024, according to Time and Date, moonrise will occur at 20:32PM. The moon will then set at 06:26AM on August 20.