SUMMERY: December 21, 2020: Jupiter passes Saturn in a close conjunction, a once-in-a-generation Great Conjunction. This Jupiter – Saturn conjunction is the closest Great Conjunction since 1623. This event occurs in the evening after sunset in western Capricornus.
On December 21, 2020, in a close conjunction, Jupiter passes Saturn in the evening sky – known as a Great Conjunction. Look toward the southwest about one hour after sunset. The bright “star” is Jupiter. Dimmer Saturn is immediately to the Giant Planet’s upper right.
Once a generation, Jupiter catches and passes Saturn. This is known as a Great Conjunction. Both planets move slowly around the sun because of their distance from our central star. A Jupiter year is nearly 12 Earth-years long while Saturn revolves around the sun in nearly 30 years. A Jupiter-Saturn conjunction is rare enough for observers to take notice of this unique pairing.
Jupiter takes nearly 20 years to move past Saturn, travel around the sun, and pass Saturn again. When Jupiter passes Saturn on December 21, 2020, they will be very close, only 0.1° apart! This is the closest conjunction since the Great Conjunction of July 16, 1623! The next Great Conjunction is October 31, 2040, when the two planets are 1.1° apart. At the next conjunction the planets are low in the east-southeast before sunrise.
As viewed from above the solar system, Jupiter passes Saturn in a heliocentric conjunction on November 2, 2020, 49 days before the great conjunction. The two planets are in along a line that starts with the sun and connects both planets. As viewed from Earth on this date, Jupiter and Saturn are 5 ° apart.
To follow the planet throughout the year, download the daily notes that are linked at the top (current month) and bottom (cumulative index of notes) of this article. Here’s what to look for during December 2020.
Look low in the southwest, one hour after sunset. Bright Jupiter is easy to locate. Dimmer Saturn is nearby, to Jupiter’s upper left. [source]