Great conjunction

A great conjunction is a conjunction of the planets Jupiter and Saturn. Great conjunctions occur regularly (every 19.6 years, on average) due to the combined effect of Jupiter's about 11.86-year orbital period and Saturn's 29.5-year orbital period. The last great conjunction happened on 21 December 2020. It was the closest great conjunction since 1623.^[1]

Great Conjunction Media

Taken with a 6" Dobsonian reflector telescope and a SV105 CMOS sensor on December 21st, Image was stacked and processed using PIPP, Registax 6, Autostakkert 3! and Adobe Photoshop.*Galilean moons Ganymede and Io are left of Jupiter, and Europa right of Jupiter. Saturn's moon Titan is located top right of Saturn.
Diagram showing the movements of Jupiter and Saturn during the 1980–81 triple conjunction
Jupiter-Saturn-great-conjunctions. In addition to a "snapshot" of the solar system, this diagram shows (as the blue epitrochoid) the position of Saturn with respect to Jupiter in a non-rotating frame of reference. In actual fact, in a non-rotating frame of reference the epitrochoid will not come back to exactly the same point after three conjunctions.
A series of great cojunctions, an illustration from Kepler's book 'De Stella Nova' (1606)
Cumulative distribution of separation distance of great conjunctions between AD 1200 and AD 2400 (blue), and an approximation formula (red)
Jerusalem sky on Nov. 12, 7BC, looking south at 18:00 - 21:30 local time (15 min. p. frame)
Separation of Jupiter and Saturn around the time of the 2020 great conjunction
Photograph taken two days before closest approach with a separation of approximately 15 arcminutes.
Great conjunction photographed on December 19, 2020, with a 360 mm (14 in) SCT telescope and color CCD.
Simulated best-case scenario view through a telescope.