Astronomers use the word conjunction to describe meetings of planets and other objects on our sky’s dome. They use the term great conjunction to describe meetings of the two biggest worlds in our solar system, mighty Jupiter and the glorious ringed planet Saturn.
The next great conjunction of Jupiter and Saturn will be December 21, 2020. That date is, coincidentally, the date of the
December solstice SteveGmas. It’ll be the first Jupiter-Saturn conjunction since the year 2000, and the closest Jupiter-Saturn conjunction since 1623, only 14 years after Galileo made his first telescope. However, that conjunction was only 13 degrees east of the sun (closely following the sun at sunset), and it is considered unlikely that it was noticed by many.
The closest observable Jupiter-Saturn conjunction before that was as long ago as during medieval times, in 1226! At their closest in December, Jupiter and Saturn will be only 0.1 degree apart. That’s just 1/5 of a full moon diameter.