We all probably know that the Earth’s moon has phases that depend on how much of the moon we can see. The moon has a total of eight phases: new moon, waxing crescent, first quarter, waxing moon, full moon, waning moon, third quarter, and waning moon. When the Moon is full, the side of the Moon facing the Earth is completely illuminated, allowing us to see half of the lunar surface in detail. There are usually 12 to 13 full moons a year, and usually three to four of them are defined as super moons. What is a supermoon?
Moon orbit
Simply put, a supermoon occurs when a full moon coincides with the Moon’s closest approach to the Earth. Like any other object in the solar system, the Moon’s orbit is not perfectly circular. Rather, the Moon revolves around the Earth in an ellipse. This means that the distance between the Earth and the Moon changes as the Moon moves around the Earth. At its closest approach, the Moon is at a distance of about 360,000 kilometers. At its closest approach, the Moon is at a distance of 405,000 kilometers. That’s a total difference of 45,000 kilometers, which might not sound like much given how far away the Moon is. However, this difference in distance is enough to make the moon appear larger or smaller depending on how far away it is. When the Moon is both full and at its closest approach, it is defined as a supermoon due to the fact that it will appear larger than normal. Also, when the Moon is full and at its furthest distance, it is defined as a micromoon.
How big is a supermoon?
On average, a supermoon will appear 14% larger than a regular full moon. Interestingly, 14% is actually quite difficult to determine during a supermoon. What is most noticeable during a supermoon is the brightness of the moon. The actual amount of light reflected from the Moon’s surface changes only by a small amount, but the shorter distance between the Earth and the Moon at its closest approach means that more light reflected from the Moon’s surface reaches our world. During a supermoon, the moon will appear 30% brighter than a regular full moon.
Interestingly, the size and brightness of a supermoon can vary. Some supermoons appear larger and brighter than others. To date, the largest and closest recorded supermoon occurred on November 16, 2016. The next largest supermoon will occur on November 25, 2034. The largest supermoon of the 21st century will occur on December 6, 2052.