Just after sunset on the evening of December 21, 2020, Jupiter and Saturn will appear closer together in Earth’s night sky than they have been since the Middle Ages, offering people the world over a celestial treat to ring in the winter solstice. Jupiter and Saturn have been approaching one another in Earth’s sky since the summer. From December 16-25, the two will be separated by less than the diameter of a full moon. Though the best viewing conditions will be near the equator, the event will be observable anywhere on Earth, weather-permitting. Hartigan said the planetary duo will appear...