Jupiter and Saturn will share the same right ascension, with Jupiter passing 6'15" to the south of Saturn.
At around the same time, the two objects will also make a close approach, technically called an appulse.
From Cambridge , the pair will be difficult to observe as they will appear no higher than 14° above the horizon. They will become visible at around 16:52 (EST), 14° above your south-western horizon, as dusk fades to darkness. They will then sink towards the horizon, setting 2 hours and 20 minutes after the Sun at 18:34.
Jupiter will be at mag -2.0, and Saturn at mag 0.5, both in the constellation Capricornus.
The pair will be close enough to fit within the field of view of a telescope, but will also be visible to the naked eye or through a pair of binoculars.
A graph of the angular separation between Jupiter and Saturn around the time of closest approach is available here.
The positions of the two objects at the moment of conjunction will be as follows:
| Object | Right Ascension | Declination | Constellation | Magnitude | Angular Size |
| Jupiter | 20h09m40s | 20°35'S | Capricornus | -2.0 | 32"5 |
| Saturn | 20h09m40s | 20°28'S | Capricornus | 0.5 | 15"3 |
The coordinates above are given in J2000.0. The pair will be at an angular separation of 30° from the Sun, which is in Sagittarius at this time of year.
The sky on 21 Dec 2020
| The sky on 21 December 2020 | ||||||||||||||||||||||||||||||||||
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50% 7 days old |
All times shown in EST.
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Source
The circumstances of this event were computed using the DE430 planetary ephemeris published by the Jet Propulsion Laboratory (JPL).
This event was automatically generated by searching the ephemeris for planetary alignments which are of interest to amateur astronomers, and the text above was generated based on an estimate of your location.
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Image credit
The Moon in conjunction with Venus and Jupiter, with the Very Large Telescope in the foreground. Image © Y. Beletsky, ESO, 2009.