Comet 3I/ATLAS Today: Latest Updates, Science Highlights, and the Week-Ahead Skywatching Forecast (Dec. 21–28, 2025)
On Sunday, December 21, 2025, the interstellar comet 3I/ATLAS is already on the “goodbye” leg of its once-in-a-lifetime pass through our solar system—two days after its closest approach to Earth. The comet is still observable with amateur gear, but it’s fading night by night as it retreats outward, while scientists race to squeeze out every last clue about what formed around another star. AP News+2NASA Science+2 This week-ahead report pulls together the key news, observing forecasts, and scientific analyses available as of Dec. 21, 2025, including new space-telescope results (X-rays!), radio searches, and NASA mission updates—plus what to expect in