If you look out your window on this clear night you will see the Flower Supermoon over Sefton

If you look out your window on this clear night you will see the Flower Supermoon over Sefton.

The so-called Flower Supermoon, the largest full Moon of 2021 will be taking to the night sky this evening. Being only 357,462km away from Earth, the Moon will appear a whole 30 per cent brighter and 14 per cent larger than some previous full Moons.

It is clear weather tonight so everyone around the globe will be able to see the Flower supermoon.

A supermoon occurs when we have a full Moon at the same time the Moon is at (or close to) perigee. This makes it appear up to 14 per cent bigger and 30 per cent brighter than a full Moon at apogee (when it’s furthest away and looks smaller and dimmer).

One in every 14 full Moons will be a supermoon.

When can I see the Flower supermoon 2021?

The full Flower supermoon can be seen from Wednesday 26 May 2021 in the UK (and around the rest of the Earth).

It will technically only be ‘full’ – reflecting the maximum amount of sunlight onto Earth – for a brief moment. This occurs when Earth comes exactly between the Moon and The Sun, a moment called ‘syzygy’ (pronounced “SIZ-eh-gee”).

In the UK, this happened at 12:13pm on 26 May. Although this means people in the country won’t be able to see the Moon at syzygy, the Moon will still appear ‘full’ two days afterwards.

What causes a supermoon?

As it's pulled around by various gravitational forces like the Earth and the Sun, the Moon doesn’t actually orbit our planet in a perfect circle. It instead moves in an elliptical shape, and how close it gets to Earth varies month by month.

At a certain point in its orbit, called perigee, the Moon reaches its closest to Earth. Then at another point, apogee, it is furthest away. The difference between these two points is an average of 48,000km.

Why is it called a Flower Moon?

Many claim the May full Moon was named by a group of Native Americans after the flowers that start to blossom at this time of the year. However, labelling the Moon such comes with a certain amount of cultural baggage.

As Dr Darren Baskill, physics and astronomy lecturer at the University of Sussex, explains:

“People often say that we take our Moon names from the ‘Native Americans’, but they aren't one group of people. There’s a danger of being culturally insensitive here. The USA is a massive landmass and is home to many different types of people.”

Over a thousand languages are spoken by Native Americans, with their cultures being as diverse as Europeans. This means different Native Americans have different names for the May Moon including the ‘field maker’, ‘blossom’ and even the ‘when the horses get fat’ Moon.

How far away from Earth is a supermoon?

Strangely, there are competing definitions of what counts as a supermoon. Some, such as astrologer Richard Nolle (who coined the term in 1979) claimed that any Moon that comes closer than 368,630km to the Earth as it appears ‘full’ can count as a ‘Supermoon’.

(The average distance between Earth and the Moon is about 382,900km, with 2021’s full Flower Moon being about 357,462 km away from us – that’s 153km closer than April’s Pink supermoon).