On December 21, 2020, the Solar System’s two gas giants will appear closer together in Earth’s night sky than they have been since 1226 CE. Jupiter and Saturn have been traveling across the sky together all year, but in December, get ready for them to really put on a show. Over the first three weeks of the month, watch each evening as the two planets get closer in the sky than they’ve appeared in two decades. Look for them low in the southwest...
