The night sky of December 2025 presents several astronomical phenomena accessible to the naked eye throughout much of Hemisfério Sul. The supermoon scheduled for December 4th opens the calendar, followed by meteor showers and planetary alignments. Observadores only need locations with low light pollution and favorable weather conditions.
- Supermoon occurs on the 4th, when the full Lua reaches perigee
- Geminids peak between December 13th and 14th
- Conjunctions involve Lua, Júpiter, Vênus and Marte throughout the month
- Summer solstice marks the 21st on Hemisfério Sul
The period favors simple observations, without the mandatory use of telescopes or binoculars.
Supermoon opens the December calendar
The supermoon on December 4th occurs at 7:38 pm Brasília time. The phenomenon records the full Lua around 357 thousand kilometers from the Terra. The lunar disk appears up to 14% larger and 30% brighter than at apogee.
The event remains visible throughout the Brazilian territory, as long as the sky is clear. The observation becomes highlighted at the time of the sunrise of Lua, close to the eastern horizon.
Geminids promise up to 120 meteors per hour
Geminidas peaks on the night of December 13th to 14th. The rain originates from particles from the asteroid 3200 Phaethon. Especialistas estimate rates of up to 120 meteors per hour in ideal locations.
The waning Lua interferes little with visibility during the peak. The radiant is located close to the constellation Gêmeos, visible from 9 pm.
The phenomenon occurs annually and is among the most intense rains of the year. Observadores report bright, colorful meteors frequently.
Conjunctions bring together planets and Lua
Several conjunctions mark December 2025. On the 4th, the supermoon forms a pair with Júpiter in the night sky. Vênus remains visible at dawn throughout the month.
Other alignments include Lua and Saturno on the 8th and Lua close to
Other rains complete the spectacle
In addition to Geminidas, Ursids peaks on December 22nd. The rain records up to 10 meteors per hour under favorable conditions. The radiant is in the constellation Ursa Menor.
Sigma Hydrids and Coma Berenicids show lower activity. Ambas remain active throughout the month, with rates of less than 5 meteors per hour.
Solstice and best observation sites
The summer solstice occurs on December 21st at 12:20 pm Brasília time. The event marks the longest day of the year at Hemisfério Sul. The maximum tilt of the earth’s axis favors shorter nights.
Regions far from urban centers offer better conditions. Áreas rural areas, mountains and distant beaches reduce the impact of light pollution. Aplicativos weather forecast helps plan sessions.
Practical tips increase chances of success
Eye adaptation to darkness takes about 30 minutes. Observadores should avoid white light from cell phones or flashlights. Posicionar facing away from artificial light sources improves contrast.
- Use reclining chairs or mats on the floor
- Bring a coat even on hot nights
- Consult digital sky maps for quick location
- Check lunar phase before each session
These measures significantly increase the number of recorded events.
The December 2025 astronomical calendar combines classical phenomena with favorable conditions in the Hemisfério Sul. The sequence begins with the December 4th supermoon and ends with the last conjunctions of the month, offering daily opportunities for direct observation of the night sky across the entire Brasil.
