Welcome to the night sky report for December 2025 -- Your guide to the constellations, deep sky objects, planets, and celestial events that are observable during the month. During the month, Comet 3I/ATLAS makes its closest approach to Earth, the Geminid meteor shower sparkles across the sky, and the Moon and Jupiter get close for a conjunction. Step outside on a cold December night when the stars shine bright to find the Big Dipper, Cassiopeia, and Cepheus. They will help you locate a binary star system (Eta Cassiopeiae), a fan-shaped open star cluster M103 (NGC 581), and a variable star (Mu Cephei). Also, throughout the month, you can find Pegasus, the winged stallion, high overhead in the south. The night sky is truly a celestial showcase. Get outside and explore its wonders from your own backyard.