A supermoon occurs when a full moon (or new moon) coincides with the Moon being at or near its closest point to Earth in its elliptical orbit — a point called perigee. The result is a Moon that appears visibly larger and significantly brighter than average. It is one of the most accessible astronomical events for non-astronomers, requiring no equipment and visible everywhere on Earth.
Why is the Moon's Distance Variable?
The Moon does not orbit Earth in a perfect circle — its orbit is an ellipse. This means the Moon's distance from Earth varies throughout the month and year. At its closest point (perigee) the Moon is approximately 356,500 km from Earth. At its farthest (apogee) it is about 406,700 km away — a difference of roughly 50,000 km, or about 14%.
When a full moon happens to fall near perigee, we get a supermoon. When a full moon falls near apogee, we get a "micromoon" — slightly smaller and dimmer than average, though the difference is barely perceptible to the naked eye.
How Much Bigger Does a Supermoon Look?
A supermoon at perigee appears up to 14% larger and up to 30% brighter than a full moon at apogee. In practice, the size difference is subtle — most people cannot tell a supermoon from an average full moon by looking at it in isolation. The Moon Illusion (the tendency to perceive the Moon as larger near the horizon) creates a more dramatic apparent size difference than the actual supermoon effect.
However, photographed side by side with a micromoon, the size difference in a supermoon is clearly visible. And the brightness difference — 30% — is noticeable outdoors on a clear night.
Best time to observe: The most dramatic visual effect occurs when a supermoon rises just above the horizon at sunset, combined with the Moon Illusion. Head to an elevated vantage point with a clear view of the eastern horizon around sunset on the night of a supermoon.
Supermoon Dates in 2026
| Date | Name | Distance (approx.) |
|---|---|---|
| 1 May 2026 | 🌺 Flower Moon Supermoon | ~358,000 km |
| 31 May 2026 | 🍓 Strawberry Moon Supermoon | ~361,000 km |
| 30 Jun 2026 | 🦌 Buck Moon Supermoon | ~357,000 km |
The Origin of the Term "Supermoon"
The word "supermoon" was coined by astrologer Richard Nolle in 1979, who defined it as a new or full moon occurring within 90% of its closest approach to Earth. The term was rarely used until around 2011, when media coverage of a particularly close supermoon brought it into mainstream use. Astronomers generally prefer the more precise term "perigee syzygy" (syzygy meaning alignment of three celestial bodies), but "supermoon" has become the established popular term.
Do Supermoons Cause Disasters?
A popular misconception claims that supermoons cause earthquakes, volcanic eruptions, and extreme weather. While the stronger gravitational pull of a perigee moon does produce slightly higher spring tides (called perigean spring tides), research has found no statistically significant increase in seismic or volcanic activity during supermoons. The tidal forces involved, while measurable, are tiny compared to the geological forces that drive earthquakes and eruptions.
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