Jupiter and Saturn Will Align to Create the First "Christmas Star" in Nearly 800 Years

They’re now really, really close to each other, and on December 21, 2020—the date of the December solstice—they’re going to almost appear to collide to become one super-bright point of light.

Jupiter and Saturn will look like a “double planet” for first time since Middle Ages. 

 

How to see Jupiter, Saturn and Mars at dusk this week.

 

"Alignments between these two planets are rather rare, occurring once every 20 years or so, but this conjunction is exceptionally rare because of how close the planets will appear to be to one another," said Patrick Hartigan, an astronomer at Rice University, according to Forbes. "You'd have to go all the way back to just before dawn on 4 March, 1226, to see a closer alignment between these objects visible in the night sky."

The event, sometimes referred to as The Great Conjunction, occurs roughly every 19 to 20 years, but this is the closest the planets will line up in the night sky since the Middle Ages. Technically, Saturn will be 10 au (astronomical units) from Earth, and Jupiter will be 5 au away, but they will appear to be less than the diameter of a full moon apart.

To catch a glimpse of the phenomenon for yourself, make sure you have a clear view to the southwest about 45 minutes after sunset. The planets will be at their closest on 21 Dec., but the "Christmas Star" will be visible from anywhere on Earth for about one hour after sunset in the northern hemisphere for the entire fourth week of December. If you're viewing with a telescope, you may also be able to see Jupiter and Saturn's largest moons orbiting them that week. The next Great Conjunction this close won't happen until 15 March, 2080, so be sure to take a peek out your window later this month for a brilliant holiday treat.


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