Don’t miss the largest supermoon of 2020 on 8 April

By Ade Ashford

The full Moon of 8 April 2020 occurs just 8½ hours after perigee, its closest point to Earth in the oval-shaped lunar orbit. This graphic shows the apparent size of this full Moon (right), 8½ percent larger than average (left). A full Moon occurring close to perigee is popularly called a supermoon, though astronomers prefer the less catchy term ‘perigee-syzygy of the Earth–Moon–Sun system’. The supermoon of 8 April is the closest full Moon of the year and we’ll not see one larger until 5 November 2025. AN graphic by Ade Ashford.
Observers in the British Isles with clear skies shortly after 7pm BST should look due east to greet the rising Moon which is almost full against the stars of Virgo. But look a little closer: does it seem a bit larger than normal? Even allowing for the subjective effects of the Moon illusion, your eyes are not deceiving you — this really is a big Moon, the largest it’ll appear throughout 2020!

The Moon’s orbit around Earth is slightly elliptical so sometimes it is closer and sometimes it’s farther away. When the Moon is full as it makes its closest pass to Earth it is known as a supermoon. At perigree — the point at which the moon is closest to Earth — the Moon can be as much as 14 percent closer to Earth than at apogee, when the Moon is farthest from our planet. The full Moon appears that much larger in diameter and because it is larger shines 30 percent more moonlight onto the Earth. Image credit: NASA.
Purely by coincidence, moonrise for the UK on Tuesday, 7 April 2020 (6:55pm London, 7:09pm Edinburgh, all times BST) occurs within a few minutes of the year’s closest perigee (the Moon’s closest point to Earth in its oval-shaped orbit). At 7:07pm on 7 April, the distance between centres of the Moon and Earth is just 356,910 kilometres, some 7.2 percent closer than average.

The lunar perigee of 7 April 2020 isn’t just the closest Moon of the year, it’s the closest that our natural satellite gets to Earth until 10am UT on 4 December 2021 when the centre-to-centre distance between the two bodies is 356,795 kilometres. How close can the Moon get? A 356,447-kilometre perigee occurs on 6 December 2052, the closest of the century.

If you’re awake around 3:35am BST on Wednesday, 8 April 2020, take a look to the southwest where you can see the lunar orb appear fully illuminated, some 8 degrees (or a little less than the span of a fist at arm’s length) to the upper right of first-magnitude Spica, Virgo’s brightest star. Occurring just 8½ hours after perigee means that this full Moon is also a supermoon and – yes, you’ve guessed it – the largest of 2020. In fact, we won’t see a larger supermoon until 5 November 2025.

The rising perigee Moon of 7 April 2020, the closest and largest Moon of the year. Image captured at 18:55 UT with a TS 65mm f/6.5 Quadruplet astrograph (TSAPO65Q) and Canon EOS 6D DSLR, ISO800, 1/400th second exposure by Ade Ashford.