‘Christmas Star’ will be closest visible conjunction of Jupiter and Saturn in 800 years at sunset.

The conjunction of the planetary giants will look like one large star on the winter solstice, Dec. 21, 2020, in the southwest sky. This hasn’t happened in 800 years. Scientists say Jupiter and Saturn will sit just 0.1 degrees apart, or about 1/5 width of the moon. The Great Conjunction of 2020 will brighten the darkest day of the year as the two giant planets of our solar system draw closer together in the night sky than they have been in centuries.

By chance, the day that Jupiter and Saturn will appear closest for Earth-based stargazers is Dec. 21, the winter solstice, which is the longest night of the year in the northern hemisphere.