December 2025 Sky Report: Essential Astronomical Events for Observation

December 2025 presents a compelling series of celestial phenomena, offering both novice and seasoned observers excellent opportunities for stargazing. This report details the month’s most significant astronomical events.

1. The Super Cold Moon

The year concludes with the final Full Moon, presenting unique characteristics for observation.

• Peak Date: Thursday, December 4, 2025.
• Significance: This Full Moon, known traditionally as the Cold Moon, achieves Supermoon status. This means the Moon coincides with its perigee (closest point to Earth), resulting in a visibly larger and brighter disk compared to an average Full Moon.
• Highest Altitude: Due to its proximity to the Winter Solstice (December 21), this Full Moon reaches the highest point in the sky for the entire year in the Northern Hemisphere, enhancing its visibility.

2. The Geminid Meteor Shower

Regarded as the most consistently active and brightest meteor display of the year, the Geminids are highly anticipated due to favorable viewing conditions this December.

• Peak Night: Overnight on Saturday, December 13, through Sunday, December 14, 2025.
• Maximum Rate: Under optimal dark-sky conditions, the shower is expected to yield peak rates of 120–150 meteors per hour (ZHR).
• Viewing Conditions: Crucially, the peak occurs when the Moon is in a thin waning crescent phase and rises late, minimizing lunar interference during the prime early morning observation hours. This makes 2025 an ideal year for viewing this specific shower.
• Origin: Unusually, the Geminids originate from the debris of an asteroid, 3200 Phaethon, rather than a comet.

3. Prime Planetary Alignments and Elongations

December provides observers with excellent views of the inner and outer Solar System planets.

• Mercury at Greatest Western Elongation (Dec 7): On December 7, the planet Mercury will reach its maximum angular separation from the Sun in the morning sky. This is a critical observation window for spotting the elusive planet, which will be visible low on the east-southeast horizon just before sunrise.
• Moon Near Jupiter (Dec 7): On the morning of December 7, the Moon will appear in close proximity to Jupiter within the constellation Gemini. This conjunction provides a spectacular naked-eye alignment.
• Saturn: Saturn remains a brilliant target throughout the month, well-placed for evening viewing, allowing observers to utilize telescopes for clear views of its rings.

4. The December Solstice

The shift of the seasons is marked by this important astronomical event.

• Date: Sunday, December 21, 2025.
• Event: This marks the Winter Solstice in the Northern Hemisphere, signifying the shortest day of the year and the commencement of astronomical winter.

5. The Ursid Meteor Shower

The final event of the month is a minor meteor shower, providing a subtle conclusion to the year’s celestial activity.

• Peak Night: Overnight on Sunday, December 21, and Monday, December 22, 2025.
• Rate: This is a low-activity shower, typically yielding 5–10 meteors per hour.
• Viewing Conditions: Viewing is enhanced by the proximity of the peak to the New Moon (December 20), ensuring minimal light pollution.

These phenomena offer rich data collection and observation opportunities for both professional and amateur astronomy. We encourage observers to utilize star charts and plan observation periods accordingly.