December 2025 offers several astronomical phenomena visible across much of the planet. The agenda includes a supermoon on the 4th, the peak of the Geminídeas meteor shower between the 13th and 14th and the approach of the interstellar comet 3I/ATLAS on the 19th. Most events can be observed with the naked eye or with simple equipment.
The month begins with intense activity in the night sky. Observadores will have access to planetary conjunctions, meteor showers and distant objects without the need for sophisticated instruments in places with low light pollution.
- Supermoon on December 4th
- Greater elongation of Mercúrio on December 7
- Geminídeas peak on December 13-14
- Close pass of comet 3I/ATLAS on December 19
Superlua opens the month’s schedule
The full moon on December 4th occurs at perigee. The satellite appears up to 14% larger and 30% brighter than normal.
The phenomenon occurs at 7:52 pm Europa Central time, visible at dusk across the entire eastern hemisphere of the planet. The maximum proximity to Terra is around 357 thousand kilometers.
Mercury reaches better position
Mercury reaches greatest eastern elongation on December 7th. The planet is visible in the morning sky, about 21 degrees from Sol.
The observation takes place on the eastern horizon about 45 minutes before the sunrise of Sol. Vênus appears nearby and makes it easier to find.
Binoculars help identify the planetary disk. Elevated and unobstructed Locais improve visibility.
Geminids reach intense peak
The Geminídeas meteor shower reaches maximum activity on the night of December 13th to 14th. Taxas reach 120 meteors per hour in ideal conditions.
The waxing moon does not interfere significantly. The radiant is in the constellation of Gêmeos, close to Castor and Pollux.
The meteors have a yellowish color. Bolas of fire occurs more frequently than in other rains.
Observation requires dark skies. Posicionar facing away from the moon increases the number of sightings.
Approaching interstellar comet
Comet 3I/ATLAS passes 270 million kilometers from Terra on December 19th. The object has origins outside the solar system.
Visibility requires medium-sized telescopes. The comet moves close to the constellation Leão.
This is the third confirmed interstellar object. The high speed differentiates the movement from common comets.
Órion nebula highlighted
Nebulosa of Órion (M42) has good visibility from December 15th. The region lies below the Órion belt.
The object appears to the naked eye as a diffuse spot in dark skies. Telescópios reveal details of the gas cloud.
The distance to Terra is approximately 1,344 light years. The nebula contains forming stars.
Solstice and conjunctions end the month
The winter solstice in the northern hemisphere occurs on December 21 at 12:03 pm Europa Central time. The day has a shorter duration of sunlight.
Saturn and the moon form a visible conjunction on December 26th. The apparent separation is about four degrees in the evening sky.
Jupiter increases progressive brightness in the last week. The planet remains visible throughout the night toward the east.
Official opposition occurs in January 2026. The four largest Galilean moons are accessible with binoculars.
Northern lights favored
High solar activity keeps the chances of auroras high at the end of the month. Regiões above 60 degrees latitude present better conditions.
The maximum of the 11-year solar cycle remains active. Tempestades geomagnetic increases probability of green and purple curtains.
Locations at Escandinávia, Canadá and Alasca concentrate observations. Daily Previsões indicate expected intensity.
