During Christmas week, the two largest planets in the solar system will do something that hasn’t been seen in nearly 800 years.
On the evening of December 21, Jupiter and Saturn will appear closer to each other than they have since the Middle Ages.
The two planets will be aligned so perfectly that they’ll look like they’re touching, creating a “double planet”.
It is fair to say that this conjunction is truly exceptional.
This rare celestial event will happen on the night of the winter solstice, and it hasn’t occurred so visibly since March 4, 1226.
“Alignments between these two planets are rather rare, occurring once every 20 years or so," said Rice University astronomer Patrick Hartigan.
"But this conjunction is exceptionally rare because of how close the planets will appear to one another."
According to Hartigan, the event will be observable anywhere on Earth — weather-permitting — in the hour right after sunset.
If you miss the main event on the 21st, don't worry. The planets will be separated by less than the diameter of a full moon between December 16 and 25.
But make sure to catch the rare sight then, because it won't occur again until March 15, 2080, and after that until the year 2400.