The moon on Sunday was the biggest and brightest of the year. Indeed, it was a supermoon: up to 14 per cent bigger and 30 per cent brighter than a regular full moon.

Sunday’s supermoon was also the largest of the three consecutive celestial beauties of the summer. The first rose on July 12 and the last will grace the night sky on Sept. 9.

During a supermoon, the moon is closer to the Earth than it is during a regular full moon. That's because the moon's orbit around the Earth is elliptical and lopsided, so that it's closer to the Earth on one side of the orbit than the other.

On average, the moon is 384,000 kilometres away, but it is about 363,000 kilometres away at the closest point, its perigee. And it is around 406,000 kilometres away at its furthest point, its apogee.

Moon orbit apogee perigee

Because the moon's orbit around the Earth is elliptical and lopsided, it's 50,000 kilometres closer to the Earth on one side of its orbit (the perigee) than the other (the apogee). (NASA)

That means that a full moon that happens during the perigee is around 43,000 kilometres closer than a full moon during the apogee, making it appear bigger.

Supermoons are moons that take place on the same day as the perigee, and on average, they happen about once every 13½ months.

On Sunday, the moon turned full during the same hour as the perigee – "arguably making it an extra-super Moon," according to NASA Science News.

The Aug. 10 perigee, which took place at 17:44 GMT (1:44 p.m. ET) was the closest of the year – the moon was just 356,896 kilometres away, according to the Lunar Perigee and Apogee Calculator hosted by Fourmilab.