How to watch the last supermoon of the year

The year’s final supermoon will illuminate December skies this Thursday, concluding a trio of these celestial events for 2025. This astronomical phenomenon occurs when the full moon coincides with the point in the moon’s elliptical orbit that brings it closest to Earth, known to astronomers as perigee.

NASA explains that supermoons can appear up to 14% larger and 30% brighter than when the moon is at its farthest point from Earth. This dramatic difference stems from the moon’s non-circular orbit, which causes its distance from our planet to vary by tens of thousands of miles throughout its monthly cycle.

“When you have a supermoon, that effect is just slightly more striking,” explains astronomer William Alston from the University of Hertfordshire. The visual enhancement is particularly noticeable when the moon is near the horizon, where an optical phenomenon called the “moon illusion” already makes our satellite appear larger.

This perceptual curiosity, which makes the moon seem bigger when viewed near the horizon than when it’s high in the sky, has puzzled scientists for generations. Despite extensive research, experts still cannot fully explain why our brains interpret the moon this way. The supermoon effect amplifies this already mysterious visual experience.

Supermoons typically occur in clusters of two to four throughout the year, as the moon’s orbit creates several opportunities when full moons align closely with perigee. Thursday’s event marks the third and final supermoon of 2025, concluding this year’s sequence of enhanced lunar displays.

Casual observers often find it challenging to detect the subtle differences between a supermoon and regular full moon without direct comparison. However, photography enthusiasts and amateur astronomers frequently capitalize on these events to capture dramatic moonrise images, when the optical illusion combines with the actual size increase to create stunning visual opportunities.

Beyond their aesthetic appeal, supermoons can have minor effects on Earth. Tidal forces are slightly stronger during these events, potentially causing marginally higher tides in coastal areas. However, these differences are generally not dramatic enough to cause concern or significant disruption to coastal communities.

For those interested in witnessing this celestial spectacle, no specialized equipment is necessary. The supermoon will be visible to the naked eye in clear night skies. Optimal viewing typically occurs during moonrise or moonset, when the moon appears near the horizon and the illusion effect is strongest.

Astronomical events like supermoons often serve as gateway experiences that spark wider public interest in astronomy. Local astronomy clubs and observatories frequently organize viewing events during supermoons, providing opportunities for community engagement with science.

While the term “supermoon” has become popular in mainstream culture, it originated relatively recently. Astrologer Richard Nolle coined the phrase in 1979, defining it as a full moon occurring at 90% or more of its closest approach to Earth. Although the term wasn’t initially embraced by the astronomical community, its descriptive nature has helped it gain widespread acceptance in scientific communication.

For those who miss this final supermoon of 2025, the celestial calendar already promises new opportunities in the coming year. Astronomical forecasts indicate several more supermoons will grace our skies in 2026, continuing this regular cycle of enhanced lunar displays.

The predictable nature of these events serves as a reminder of the clockwork precision of our solar system, offering both scientific value and aesthetic pleasure to observers around the world.