Two supermoons to happen in single month – how to see them in the UK

Stargazers will be treated to some magical sights in the night sky in August, thanks to the appearance of two supermoons as well as the phenomenon known as a 'blue moon'.

Supermoons are when the moon is closest in its orbit to the Earth, making it appear bigger and brighter than usual.

There will be two supermoons – one on Tuesday, 1 August and another again on Wednesday, 30 August — when it will be even closer to the Earth.

The second will also be known as a blue moon – the name given to the phenomenon of two supermoons in one month.

Catherine Heymans, astronomer royal for Scotland, said August will be an "exciting month for observing the moon".

Speaking on BBC Radio 4, she urged people to "look up at our gorgeous night skies".

Here is everything you need to know about supermoons and blue moons, and where to see them this month:

Where and when can I watch the supermoon?

The supermoon itself is due on 1 August, but Heymans said people will be able to see it the following day too.

"The actual fullest moon is happening at 7.30pm [on Tuesday] night but we won't see it because it's below the horizon," she told Radio 4.

"What I want people to do for the next three days is if you're down south about 9pm at night or if you're up north about 10pm that's when the moon's going to be rising above the horizon.

Read more: Supermoon: Does it really affect your sleep and mood?

"And it will really look like a supermoon then because when you've got something to compare the size of the moon to on the horizon, some perspective, it looks absolutely huge even though it's just an optical illlusion.

"When you see the clouds clearing in the next three days please please head out and have a look at this gorgeous full moon.

"It's lovely warm weather at the moment – go and lie out in a field somewhere, take your binoculars or even your smart phone, some of these smart phones at the moment have amazing cameras on them.

"Zoom in on those craters, look at the shadows that the sunlight is casting in the depths of those craters. It's absolutely gorgeous and well worth a trip out to look up at our gorgeous night skies."

What is a supermoon?

A supermoon is when the moon is at the closest point to the Earth during its orbit, explained Heymans.

She said: "The moon is orbiting the Earth every 27 days and it's not orbiting in a circle, so sometimes it's closer to the Earth and sometimes it's further away.

"When it's at its closest point we call it a supermoon and these happen roughly three to four times a year."

The lunar cycle - the cycle of the moon going from new moon to full moon and back again - is 29.5 days, she added, and is due to how the moon, the Earth and the sun are all lined up with each other.

"Usually you have a full moon once every calendar month but because the lunar cycle is slightly less than the typical length of the month, sometimes you get two moons in a calendar month," she added.

"Both of the full moons in August are going to be supermoons, so that's when the moon is closest to the Earth."

A supermoon is often only 6% brighter than a normal moon, Heymans said, but can often appear much much larger and brighter - especially when seen compared to buildings on the horizon.

What is a blue moon?

A blue moon is essentially the second full moon in a calendar month, which only happens roughly every two-and-a-half years, said Heymans.

"The astronomical definition of a blue moon is slighty more complicated," she said. "Basically it's roughly when there are two moons in a calendar month, which is happening in August

"It's a special time where you've got two in the same month."

This month, even more special is the fact the blue moon event is combined with two supermoons.

When are the supermoons in August

The supermoons are due to happen on Tuesday evening (1 August) and again on Wednesday, 30 August.

Heymans said people would be able to see the moon looking particularly bright in the days around the supermoons, so it is worth looking up into the skies.

Watch: First supermoon of the year shines over London