The night sky often presents us with breathtaking phenomena, and few are as captivating as a full Moon glowing with a vibrant orange hue or appearing unusually large. As July’s full Moon, traditionally known as the Buck Moon, graces the skies in 2025, skywatchers in the Northern Hemisphere are poised to witness these striking displays. This year, the Buck Moon is expected to be one of the lowest-lying full Moons, enhancing its visual impact and prompting questions about its altered appearance.
The Moon’s captivating orange glow is a real phenomenon rooted in the physics of light and Earth’s atmosphere. When the Moon hangs low on the horizon, its light must travel through a significantly greater thickness of our planet’s atmosphere compared to when it’s high overhead. As explained by BBC Sky at Night Magazine and Wonderopolis, Earth’s atmosphere is filled with tiny particles that scatter light. Shorter wavelengths of light, such as blue and violet, are scattered more efficiently in all directions. This is precisely why our sky appears blue during the day. Conversely, longer wavelengths, like red and orange, are less scattered and are able to pass through the atmosphere more directly to our eyes. This selective scattering leaves the Moon appearing a vivid orange or even a rusty red. This effect is similar to why sunrises and sunsets often display a spectrum of reds and oranges. Beyond the horizon effect, atmospheric elements like dust, pollution, or smoke from wildfires can also contribute to a reddish or orange lunar appearance, even when the Moon is higher in the sky, as noted by El PaĆs.
While the orange color is a genuine atmospheric effect, the perception of the Moon appearing unusually large when it’s low in the sky is an entirely different phenomenon known as the ‘Moon illusion.’ Despite how convincing it may seem, the Moon’s actual size and distance from Earth do not significantly change over the course of a single night. As NASA emphatically states, “it’s all in your head. Really. The Moon’s seeming bigness is an actual illusion, rather than an effect of our atmosphere or some other physics.” This optical illusion is believed to stem from how our brains process visual information, particularly when there are foreground objects like trees, mountains, or buildings to provide a sense of scale and distance. When the Moon is high in the sky, with no immediate reference points, our brains tend to perceive it as smaller. You can easily test this illusion by holding your outstretched finger next to the Moon, looking at it through a paper tube, or even bending over and looking backward between your legs; in these instances, the Moon will appear its true, smaller size. Even astronauts in orbit report experiencing this illusion, suggesting its complexity.
The July 2025 full Moon, dubbed the Buck Moon, is named for the time of year when male deer (bucks) begin to grow their new antlers. This particular Buck Moon is notable for being one of the lowest-lying full Moons of the year in the Northern Hemisphere, which will amplify both the orange hue and the ‘Moon illusion.’ According to the Manchester Evening News, the full Moon is expected to rise at 10:10 PM UK time on Thursday, July 10, becoming visible in the southeastern sky as the Sun sets.
Beyond the Moon itself, skywatchers will have additional celestial treats during the night of the Buck Moon. Mars, the Red Planet, will be visible in the western sky near the constellation Leo and the bright star Regulus, setting around 11:37 PM. Early risers on July 11 can also spot Saturn, which will rise just after midnight and be visible in the morning sky before sunrise around 5 AM. Venus, the brightest planet in our night sky, will make its appearance around 2 AM, shining brilliantly in the eastern sky, often near Saturn.
The interplay of light, atmosphere, and human perception creates these stunning lunar spectacles. Whether it’s the scientific scattering of light that paints the Moon orange or the fascinating trick of the ‘Moon illusion’ that makes it appear colossal, these moments remind us of the wonders of our universe and the intricate ways we experience them. So, as the Buck Moon rises, take a moment to gaze upon its beauty and appreciate the science behind its captivating display.
