Overview
- The Cold Moon becomes a supermoon on December 4, widely visible globally, reaching full phase at 23:14 GMT.
- Mercury attains greatest western elongation on December 7, providing its best morning apparition of the year.
- The Geminids peak the nights of December 13–14 and can reach about 150 meteors per hour under dark skies, with a last‑quarter Moon reducing glare.
- The Ursids peak around December 22–23 with typical rates of 5–10 per hour, favoring Northern Hemisphere observers and benefiting from darker skies near the new Moon.
- December lunar phases are Full on Dec. 4, Last Quarter on Dec. 11, New Moon on Dec. 19, and First Quarter on Dec. 27; guidance recommends dark locations, unaided eyes, and 15–20 minutes for night vision adaptation.