Here are some details on the Moon’s phases, close approaches of planets and other astronomical events in December.
December 3: Conjunction – Close approach of Uranus (mag +5.6) and the Moon (98%).
Uranus lies below the Moon. It can be seen with binoculars or a small telescope.
December 3: Conjunction – Close approach of the Moon (98%) and the young open star cluster M45 (the Pleiades). This time, M45 will lie slightly above and to the left of the Moon from sunset to sunrise on the night of the 6th to the 7th. Uranus (mag +5.6) will lie lower and to the right of M45, visible with binoculars or a small telescope throughout the night.
December 4: Moon at perigee (99%) at 6:13 a.m. EST, when it reaches its closest point to Earth (356,967 km).
December 4: Full Moon (100%) at 6:14 p.m. EST.
December 5: Mercury at its highest altitude. Seen from Montréal, Mercury will reach its highest point in the sky during its morning appearance from November 2025 to January 2026. It will shine brightly at magnitude –0.5. This appearance is reasonably well positioned but still challenging to see, reaching a maximum altitude of 16 degrees above the horizon at sunrise on December 5.
December 7: Mercury at greatest western elongation in the morning sky. Mercury reaches its greatest separation from the Sun during its morning appearance from November 2025 to January 2026, shining brightly at magnitude –0.5.
December 7: Conjunction – Close approach of Jupiter (mag –2.5) and the Moon (91%).
The Moon and Jupiter will appear closest on the morning of the 7th, but will be visible from December 6 to 8. Jupiter will lie above and to the right of the Moon. The pair will become visible each night around 9:30 p.m., rising in the east.
December 10: Conjunction – Close approach of the Moon (66%) and Regulus (mag +1.4). Regulus sits just to the right of the Moon. An occultation will be visible for regions of Quebec located north of a line running between Radisson and Havre-Saint-Pierre.
- Kuujjuaq (start: 1:09:18 a.m. – end: 2:00:03 a.m.)
- Radisson (start: 1:15:01 a.m. – end: 2:09:59 a.m.)
- Schefferville (start: 1:20:32 a.m. – end: 2:05:37 a.m.)
- Havre-Saint-Pierre (start: 1:41:32 a.m. – end: 1:51:28 a.m.)
December 10: Neptune ends its apparent retrograde motion and resumes its eastward path.
This phenomenon, caused by Earth’s changing perspective as it orbits the Sun, occurs a few months after opposition.
December 11: Last Quarter Moon (50%) at 3:51 p.m. EST.
On December 13, the Geminids reach their peak around 10 p.m. EST. This meteor shower is active from December 4 to 21, and its radiant in the constellation Gemini will be visible all night. Under a dark sky, you can expect 100 to 150 meteors per hour, with favourable conditions thanks to a mostly unobtrusive Moon. The best time to observe is late on the night of the 13th to the 14th or before dawn on the 14th, when the radiant is high in the sky. Find a comfortable spot away from lights and enjoy the show!
December 18: Conjunction – Close approach of Mercury (mag –0.5) and the Moon (3%).
Low on the ESE horizon around 7 a.m., with the Moon slightly lower and to the right of Mercury.
December 19: New Moon (0%) at 8:43 p.m. EST.
December 21: Winter solstice (10:03 a.m. EST) in the Northern Hemisphere—the shortest day of the year. The Sun reaches its southernmost point in the constellation Capricorn (23.5°S), marking the astronomical start of winter. In the Southern Hemisphere, it is the longest day and the start of summer.
December 26: Conjunction – Close approach of Saturn (mag +1.1) and the Moon (39%).
The Moon will lie above and to the right of Saturn from sunset until around 11 p.m.
December 26: Conjunction – Close approach of Neptune (mag +8.1) and the Moon (41%).
Neptune will lie above and to the left of Saturn.
December 27: First Quarter Moon (50%) at 2:09 p.m. EST.
December 31: Conjunction – Close approach of Uranus (mag +5.9) and the Moon (85%).
Visible from sunset to moonset. Uranus trails the Moon to its left. It can be seen with binoculars or a small telescope.
December 31: Conjunction – Close approach of Saturn (mag +1.4) and Neptune (mag +8.5).
Neptune follows Saturn in its apparent motion throughout December and will lie above and to the left of it. The two planets will be closest on the evening of December 31, starting at sunset.
December 31: Conjunction – Close approach of the Moon (85%) and the open star cluster M45 (the Pleiades). From sunset to sunrise on the night of December 31 to January 1, M45 will lie slightly above and to the left of the Moon—a beautiful sight to end the year. Uranus (mag +5.63) will lie farther to the left of the Moon, visible with binoculars or a small telescope throughout the night.
