The Royal Observatory Greenwich explained: “The term ‘Supermoon’ originates from a concept in astrology, but has been adapted and given a strict definition within astronomy.
“If the Moon is within 10 percent of its closest distance of Full Moon, it is considered to be a Supermoon.”
When is the next Supermoon?
The exact date of the next Supermoon is something of a hotly debated topic.
Many astronomers stick to a strict definition of what makes a Supermoon, which only considers the closest Full Moons at perigee in a given year.
By this definition, there will be two Supermoons this year, on April 27 and May 26 respectively.