During the "Great Conjunction" on Dec. 21, 2020, Jupiter and Saturn will be about one-tenth of a degree apart, their closest approach since 1623.

Jupiter and Saturn's great conjunction: How to see the 'Christmas star' tonight How to watch the closest observable rendezvous of the two giant planets since the Middle Ages.

Jupiter and Saturn will come within 0.1 degrees of each other on December 21, 2020, during what is known as the "great conjunction." Getty Images How to watch the great conjunction ...

A Jupiter-Saturn conjunction happens every 20 years, but this one is the closest since 1623, according to EarthSky.com. This kind of extra-close conjunction won’t happen again until March 15, 2080.

This solar system chart shows the positions of Jupiter and Saturn during the "great conjunction" on Dec. 21, 2020, when the two planets will appear just one-tenth of a degree apart in the night sky.

If you missed seeing the great conjunction in person because of the cloud cover, the next super-close pairing is March 15, 2080.

For skygazers on Earth, Jupiter and Saturn will appear closer together on Dec. 21 than they have been since the Middle Ages, almost 800 years ago.

Saturn, top, and Jupiter, below, are seen after sunset from Shenandoah National Park, Sunday, Dec. 13, 2020, in Luray, Virginia. The two planets are drawing closer to each other in the sky as they ...

Saturn, top, and Jupiter, below, are seen after sunset from Shenandoah National Park, Sunday, Dec. 13, 2020, in Luray, Virginia. The two planets are drawing closer to each other in the sky as they ...

Jupiter and Saturn have their conjunction every couple of decades, but some are more notable than others — and 2020 is one of those special years.

This December, Jupiter and Saturn will put on a show for skygazers that hasn’t been seen in roughly 800 years. Astronomers are calling it the Great Conjunction of 2020. On December 21 ...