This Thursday, December 4, 2025, Lua reaches its full phase, with the entire disk illuminated by Sol. The phenomenon occurs at 8:14 pm, Brasília time, marking the peak of the current lunar cycle. Essa aligned position between Terra, Sol and natural satellite generates full visibility in the night sky.
December’s supermoon, the third in a row this year, brings the star closer to Terra, making it slightly larger and brighter. Observadores across the planet, especially in the southern hemisphere, you can notice the effect at sunset.
The lunar cycle, which lasts an average of 29.5 days, influences tides and animal behavior, according to astronomical studies. Essa specific phase stands out for occurring in Gêmeos, adding an astrological feature to the event.
What defines the full moon in December
The full moon appears when Lua is positioned opposite Sol in relation to Terra. Nesse alignment, the entire visible face reflects sunlight directly.
This configuration creates spring tides, with higher and lower levels in the oceans. Lunar and solar gravity combined amplify the phenomenon, affecting global coastlines.
Astronomers record that December 2025 brings a supermoon, as the perigee coincides with the full phase. The average distance of 384 thousand km reduces to around 363 thousand km, intensifying the brightness.
Complete calendar of December phases
The synodic month begins with the waxing moon of November and progresses to the December cycle.
- Crescent moon: November 28th, at 3:58 am
- Full moon: December 4th, at 8:14 pm
- Waning moon: December 11th, at 5:51 pm
- New moon: December 19th, at 10:43 pm
- Crescent moon: December 27th, at 4:09 pm
These dates are based on precise calculations of Instituto Nacional from Meteorologia. Cada transition marks a change in the illuminated portion, visible to the naked eye on clear nights.
The progression follows the orbital movement of Lua, completing the cycle in 29 days and 12 hours. Observadores can track daily variations for nighttime activity planning.
Natural influences of the current supermoon
December’s supermoon directly affects the oceans and coastal ecosystems. Marés high levels are recorded in ports such as Santos and Rio from Janeiro, with peaks expected for the early hours of Friday.
Marine species, such as corals and turtles, synchronize reproductive cycles with this phase. Estudos indicate that intense light alters feeding patterns in migratory birds.
In the southern hemisphere, the lunar disk appears inverted compared to the north, with the illuminated part on the left during crescent. Essa geographic perspective changes visual observation.
The orbital proximity, at 363 thousand km, increases the apparent diameter by 14% and the brightness by 30%. Telescópios amateurs capture details such as craters and basalt seas.
How to observe the full moon safely
To view the event, choose locations with little light pollution. Moonrise occurs around 7pm, just after sunset.
Use binoculars to magnify craters like Tycho and Copernicus. Evite look directly at Sol during alignments, prioritizing twilight.
Astronomy apps provide real-time alerts. In cities like São Paulo, elevated parks offer unobstructed views.
The duration of the full phase lasts for approximately three days, with lighting above 99%. Condições favorable weather conditions multiply observation opportunities.
Scientific Details of the Lunar Cycle
The lunar cycle results from the synchronous rotation of Lua, which takes 27.3 days to orbit Terra. The synodic lunation, lasting 29.5 days, considers the position relative to Sol.
Statistics from Inmet show that 2025 sees 12 full moons, with three supermoons later in the year. The perigee in December coincides exactly with solar opposition.
Lunar gravity, 1/6 of Earth’s, moves about 70% of the water in the oceans. Tides of syzygy at full moon doubles the amplitude in relation to intermediate phases.
Experiments with satellites confirm that the orbital ellipse varies in distance by 42 thousand km annually. Essa variation explains differences in apparent size over the months.
Intermediate phases and transitions
After the full moon, the waning begins, with the lighting gradually decreasing. Essa stage lasts until December 11th, when it reaches its last quarter at 5:51 pm.
The transition to a new moon on December 19 aligns the satellite between Terra and Sol. Nessa position, the disk completely darkens, ideal for stellar observations.
The crescendo resumes on December 27, with 4:09 p.m. marking the first quarter. Partial Iluminação grows until the next cycle.
These changes occur regardless of hemispheres, but visual orientation differs. No Brasil, the illuminated face advances from right to left.
Astronomical curiosities for 2025
December 2025 includes the Geminídeos meteor shower, peaking on December 13-14. The waning moon interferes less with the visibility of features.
September’s lunar eclipse still echoes in calendars, but December focuses on the supermoon. Tradições cultures associate the flood phase with harvests and rituals.
Lua, 384 thousand km away, on average orbits at 1 km/s. Sua surface, covered by regolith, reflects 12% of incoming sunlight. Registros Historical observations date Babylonian observations 3 thousand years ago. Hoje, missions like Artemis plan human returns in 2026.
