A full moon occurring when the moon is within 90% of its closest approach to Earth. This will be the second of four consecutive supermoons in 2024. Known for being the biggest and brightest moons of the year. The full Moon closest to the autumnal equinox.

As the Earth passes between the sun and the moon, a fleeting shadow will be cast on the planet's only natural satellite on Tuesday.

The full moon on Sept. 17, which is called the Harvest Moon, will be followed a day later by a supermoon on Sept. 18. This close timing creates a special dynamic, as the Harvest Moon, which is the full moon closest to the autumnal equinox, takes center stage with an added boost.