Once in a blue moon: Stargazers treated to second supermoon in same month

A spectacle that has not been seen since 2009 - ITV News' Nick Wallis explains why astronomers are so excited about the super blue moon over the night sky

Stargazers may have seen the beautiful supermoon earlier this month, known as the Sturgeon Supermoon.

During the early hours of Thursday 31st August we'll see the second full supermoon of the month, known as the blue moon.

What is a Blue Moon?

A 'blue moon' is the second full moon in a calendar month with two full moons. Hence you've probably heard the phrase "once in a blue moon".

As it takes 29.5 days for the moon to complete one orbit of the Earth you rarely get two full moons in a month. But this month's blue moon is more special as it's a supermoon.

This supermoon will be even closer to earth than the one at the beginning of August, at a distance of 222,043 miles (357,344km).

The supermoon, seen here on Tuesday at Fort Baker, California, has been visible for a few nights but will peak on Wednesday. Credit: AP

The moon will look around 14% bigger and 30% brighter than the average full moon. Although you might not be able to tell it's actually that bigger.

The moon will also be in close proximity to Saturn on the same day. A blue moon is very rarely blue.

Where and when can I see it?

Look to the east shortly after sunset on August 30 and to the west before sunrise on August 31 where it will be lower as it sets. It will be highest in the sky around midnight.

Provided skies are clear, binoculars or telescopes should help you to see the supermoon, though it should be visible to the naked eye.

How often do we get full moons?

Full moons occur every 29.5 days when the moon has completed its lunar phase cycle fully.

The last time two full supermoons graced the sky in the same month was in 2018.

This year’s first supermoon was in July. The fourth and last will be in September.

The next time we will have a closer supermoon will be November 5 2025.

Why do we name Full Moons?

All full moons are given names, which are often linked to the time of year they occur. The names were given by Native Americans in North America in a bid to track the seasons.

There are some variations in the list, depending on where you look, as different tribes and settlers around the world created their own. However, the most common is the Farmers Almanac list.

The blue moon's name comes from the phrase 'once in a blue moon'.

The supermoon appears larger as it is closer to the Earth than usual. Credit: AP

What is a supermoon?

A supermoon is when the moon appears a little bit bigger and brighter in the sky.

As the moon goes around the Earth, there are points in its orbit in its full moon phase where it is slightly closer to Earth, known as its 'perigee': around 360,000 km away and 22,000 km closer.

It means it looks a little larger and more vivid to the naked eye.

When the moon viewed near the horizon looks larger than usual, your brain is playing a trick on you - it’s called the moon illusion.

The moon rising over a church in Hyderabad, India, on Wednesday night. Credit: AP

How do Supermoons impact the tides?

New and full moons create Spring tides. This is where high tides are higher and low tides are lower than average. Spring tides give us the largest tidal range form high to low. 

During a supermoon, the moon is closer to the earth and therefore has a larger gravitational pull on the worlds oceans.

As a result, a supermoon can create a slightly higher than normal spring tide.

This highest tide is sometimes referred to as a "King Tide" or, to give it it's official name, a Perigean Tide.

Coastal flooding impacts can become quite severe when King Tides coincide with adverse weather conditions and tidal surges, particularly during the winter months.

How will the supermoon impact Hurricane Idalia in the USA?

The strong winds from hurricanes have the ability to push large amounts of water ashore causing majoring costal flooding impacts. This is known as a storm surge. A storm surge can travel several miles inland, especially along bays, rivers, and estuaries.

The storm surge from Hurricane Idalia is set to combine with the king tides formed by the supermoon, producing much higher tidal surges and increasing the volume of water compared to normal.

Some places along the pan handle of Florida are expected to see a storm surge of more than 12 feet.

Peak Storm Surge Forecast expected from Hurricane Idalia Credit: US National Hurricane Center

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