For the first time since the Middle Ages, Jupiter and Saturn will become so close to each other in the night sky that they'll appear as a very bright "double planet” in the southwestern sky. It’s called ‘The Great Conjunction' -- when two objects appear to be very close together in the night sky.

It will be visible in Iowa shortly after sunset on the winter solstice, December 21st. The sun will set on the first evening of Winter at 4:40 in Cedar Rapids.

But don’t wait too long, because the planets will dip below the horizon only a couple of hours after sunset. You won’t see anything like this again until March 15, 2080.

At their closest on the evening of 12/21, they’ll be only 0.1 degrees apart. The last time Jupiter and Saturn appeared this close was in 1623. According to earthsky, that conjunction was close to the sun and it is unlikely that it was noticed by many. The closest observable Jupiter-Saturn conjunction before that was during medieval times, in 1226.

But you don’t have to wait until the first day of winter to see these two gas giants. They’re visible every night right now (weather permitting) in the southwestern sky.

The last ‘Great Conjunction’ of Saturday and Jupiter occurred May 28, 2000, but was almost impossible to view because it occurred while the two planets were close to the sun.

Jupiter is five times the distance of Earth from the sun, around 484 million miles away, and takes a dozen years to orbit the sun. Saturn is almost double that and takes 29 years to orbit the sun.

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