Why the Moon occasionally appears larger and brighter in our night sky

Space · Published 25 October 2026 Swipe more like this →

In short: The Moon does not stay at a constant distance from Earth. Because its orbit is elliptical rather than a perfect circle, it swings between two extremes. When a full Moon coincides with its closest approach, it creates a visual spectacle that can make the lunar orb appear significantly larger.

A supermoon occurs when the Moon reaches its perigee—the point in its elliptical orbit where it is closest to Earth. At this position, it can appear about 14% bigger and 30% brighter than a full Moon occurring at apogee, which is the point where the Moon is farthest away. The distance between these two orbital extremes is approximately 30,000 miles (50,000 km). The orbital path creates a significant variance in distance between these two points. These specific celestial mechanics dictate the frequency of these rare visual events. For instance, a notable perigee moon occurred in 1993.

While these percentage changes are difficult for the human eye to detect when the Moon is high in the sky, the effect is much more pronounced when the Moon is low on the horizon. In these moments, the Moon can appear so large that it seems reachable. NASA scientists use these events as opportunities to encourage public observation of the lunar cycle. Observers often find the most striking views when the lunar orb is framed by silhouettes of trees or buildings. This perspective emphasizes the scale of the glowing sphere. Scientists suggest these moments are ideal for beginning a regular practice of lunar observation.

The Moon's orbit is also tilted relative to Earth's orbit around the Sun. This means that most full Moons pass above or below the Earth's shadow. However, about twice a year, a full Moon aligns perfectly with the Earth and Sun, resulting in a total lunar eclipse. During these events, the Moon can take on a reddish 'blood moon' hue as it reflects the light of every sunrise and sunset occurring on Earth simultaneously. During a total eclipse, the Moon loses its usual brightness to take on an eerie, faint glow. This happens because only scant sunlight manages to penetrate our atmosphere. The resulting reddish color comes from the specific way the atmosphere bends the light. These events are visible from various regions, including western North America and Eastern Asia.

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