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Have you ever seen a blue supermoon? Tonight, if the skies are clear, you'll have a chance to see this rare event.
But what is a blue supermoon? Is it blue, and when is the best time to see it?
We’ve got the advice from the experts, and reveal why the moon is about to become so important to every single one of us.
We’ve all heard the saying 'once in a blue moon', so we know how rare it is.
But what is a blue supermoon and what makes it extra special? Dr Affelia Wibisono, astronomer at the Royal Greenwich Observatory, explains that it's a combination of two rare astronomical events occurring at the same time.
“Firstly, we have a super full moon, which is what happens when the full moon coincides with when the moon is at (or very close to) its nearest point to the Earth," Dr Wibisono explained.
"Super full moons appear very slightly bigger and brighter compared to a ‘normal’ full moon."
However, it's also a blue moon.
Confusingly there are two different definitions of a blue moon.
Normally there are 12 full moons in a year, one in each calendar month. But the lunar cycle does not always match our calendar.
A blue moon happens every two to three years when there are two full moons within a single calendar month.
However a blue moon can also be defined as the third full moon in an astronomical season - these begin and end at the equinox and solstice - tonight's blue supermoon falls under this seasonal definition.
Dr Wibisono added that even though it is called hue, you won't see a change in colour, saying: "The moon will not take on a blue hue and will instead retain its usual white colour.”
The blue supermoon will rise in the UK at about 8:50pm tonight (Monday August 19) and will set at approximately 6:35pm.
“However, the moon will not look noticeably different during the night, so the best time to see it will depend on the observer’s local conditions,” Dr Wibisono explained.
The moon will appear up to 14% bigger and 30% brighter than when it is furthest away from the Earth. It will be at 222,043 miles (357,344km) compared to its furthest point of 252,088 miles (405,696km).
With the moon so big in our skies, it’s a great opportunity to grab a pair of binoculars and give it a closer look.
Dr Wibisono explained that you can see many of the moon’s natural features, but if you’ve got a pair of binoculars to hand, you’ll see even more on the surface of the Earth’s only natural satellite.
These include:
Dr Wibisono says: “Binoculars will reveal more details on the crater, such as its slumped inner walls and the 2km [one-and-a-quarter-mile] tall mountain at the centre of the crater’s floor.
“You’ll also be able to see other smaller craters and mountain ranges around the moon’s surface.”
Geopolitical and astropolitical expert Tim Marshall is author of the best-selling book The Future of Geography – about the new political space race.
He explained that the moon is set to become the centre of attention for all of us. For the first time since 1972, when we look up at the moon a man and a woman will soon be looking right back at us.
“Get the popcorn ready,” he told Saga Magazine. “The USA plans to have a woman and a man walking on the Moon in 2026. It’s part of the Artemis Accords mission, to which the UK is a signatory."
India has landed a robot on the moon and China expects to have its astronauts taking their first lunar steps before 2030.
Marshall added that this new interest isn’t just about space exploration, it’s the start of a space gold rush to try to capitalise on what’s thought to be on the moon’s surface.
“We can expect bases to be built on the moon by the early 2030s,” he said. “This is because of the huge potential for mining the metals that we need for renewable energy technology on Earth – which are now thought to be at the lunar south pole.
“The economic model of making that profitable is unproven, but that won't stop companies and countries from trying."
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