The Moon – 29 December 2025
Key Scientific Data
Object type: Earth's natural satellite
Date of observation: 29 December 2025
Local time: 21:23
Phase: Waxing Gibbous Moon
Moon age: 9.6 days
Illuminated fraction: 72.1%
Distance from Earth: 361,863 km
Apparent diameter: 33′ 00.65″
Physical diameter: 3,474.8 km
Apparent magnitude: –11.39
Phase angle: 63° 45′
Average albedo: 0.12
Orbital velocity: 1.067 km/s
Sidereal orbital period: 27.32 days
Synodic period: 29.53 days
Light-travel time: approximately 1.2 seconds
Description
This photograph captures the waxing gibbous Moon on 29 December 2025 at 21:23 local time, when it was 9.6 days old and 72.1% illuminated.
At a distance of 361,863 kilometres from Earth, the lunar disc appeared approximately 33 arcminutes across, slightly larger than its average apparent diameter.
The waxing gibbous phase offers an excellent opportunity to observe lunar geography. While the illuminated hemisphere reveals extensive dark maria and bright highlands, the boundary between sunlight and darkness highlights craters, mountain ranges and other surface formations.
The Terminator and Lunar Landscape
The terminator is the boundary separating lunar day from lunar night.
Near this line, sunlight strikes the surface at a very low angle, casting long shadows from crater rims, mountains and elevated terrain.
These shadows reveal the Moon's topography with remarkable clarity, making the waxing gibbous phase particularly suitable for studying surface relief.
At Full Moon, sunlight illuminates the visible lunar surface more directly, reducing shadows and making many geological formations less pronounced.
The Lunar Maria and Ancient Highlands
The large dark regions visible across the Moon are known as lunar maria, vast plains of ancient basaltic lava.
They formed when molten material flooded enormous impact basins billions of years ago, subsequently cooling and solidifying.
The brighter lunar highlands are generally older and more heavily cratered, preserving evidence of the intense bombardment experienced during the early history of the Solar System.
Unlike Earth, the Moon has virtually no atmosphere, liquid-water erosion or active plate tectonics, allowing many impact structures to survive for billions of years.
Its surface therefore represents an exceptionally well-preserved geological record of the early Solar System.
Lunar Phases and Synchronous Rotation
The Moon's phases result from the changing geometry between the Sun, Earth and Moon, rather than from Earth's shadow.
Approximately half of the Moon is always illuminated by the Sun, but the fraction visible from Earth changes throughout its orbit.
At the time of this observation, 72.1% of the visible lunar disc was illuminated, with the illuminated fraction increasing towards Full Moon.
The Moon also rotates on its axis, completing one rotation in approximately 27.32 days, matching its orbital period around Earth.
This phenomenon, known as tidal locking, explains why essentially the same lunar hemisphere always faces our planet.
However, small apparent oscillations called librations allow observers to see approximately 59% of the lunar surfaceover time.
A Moon Closer Than Average
At the moment of observation, the Moon was 361,863 km from Earth, approximately 22,500 km closer than its mean distance of 384,400 km.
Because its orbit is elliptical, the Moon's distance and apparent diameter change throughout the lunar month.
In this photograph, its apparent diameter measured 33′ 00.65″, slightly larger than average.
Despite its brilliant appearance, the Moon reflects only about 12% of the sunlight reaching its surface, corresponding to an average albedo of approximately 0.12.
Its apparent brightness of magnitude –11.39 nevertheless makes it one of the most prominent objects in Earth's night sky.
Curiosities
The Moon travels around Earth at approximately 1.067 km/s, equivalent to more than 3,800 km/h.
Its sidereal orbital period is 27.32 days, while the interval between identical lunar phases, known as the synodic period, is approximately 29.53 days.
The difference arises because Earth continues orbiting the Sun while the Moon completes its revolution.
The Moon is also the only celestial body beyond Earth on which humans have walked.
Between 1969 and 1972, six Apollo missions landed astronauts on its surface, with twelve people directly exploring the lunar landscape.
Looking Back in Time
At a distance of 361,863 kilometres, reflected sunlight takes approximately 1.2 seconds to travel from the Moon to Earth.
Unlike distant galaxies, whose light may have travelled for millions or billions of years, the Moon is therefore observed almost in real time.
Yet its surface tells a very different story.
Much of the ancient lunar highlands formed more than four billion years ago, while the dark basaltic maria preserve evidence of volcanic activity dating back billions of years.
This photograph therefore combines two extraordinary timescales:
Light only 1.2 seconds old, reflected from a landscape billions of years old.
Image Data
Target: Moon
Date: 29 December 2025
Local time: 21:23
Phase: Waxing Gibbous
Moon age: 9.6 days
Illuminated fraction: 72.1%
Distance from Earth: 361,863 km
Apparent diameter: 33′ 00.65″
Altitude at observation: 55° 54′
Filter: Luminance
Binning: 1×1
Gain: 100
SQM: 18.35
Equipment:
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Telescope: Artesky ARTEC 250 Pro
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Mount: 10Micron GM2000 HPS II
For further details and the full-resolution image, visit AstroBin: