The Moon, Jupiter and Saturn will make a close approach, passing within 2°56' of each other. The Moon will be 3 days old.
From Cambridge , the trio will become visible at around 16:32 (EDT), 18° above your south-western horizon, as dusk fades to darkness. They will then sink towards the horizon, setting 2 hours and 36 minutes after the Sun at 18:48.
The Moon will be at mag -10.1 in Capricornus; Jupiter will be at mag -2.0 in Sagittarius; and Saturn will be at mag 0.5 in Capricornus.
They will be too widely separated to fit within the field of view of a telescope, but will be visible to the naked eye or through a pair of binoculars.
At around the same time, the trio will also share the same right ascension – called a conjunction.
A graph of the angular separation between the Moon and Jupiter around the time of closest approach is available here.
The positions of the trio at the moment of closest approach will be as follows:
| Object | Right Ascension | Declination | Constellation | Magnitude | Angular Size |
| The Moon | 20h09m40s | 23°34'S | Capricornus | -10.1 | 31'46"0 |
| Jupiter | 20h05m50s | 20°46'S | Sagittarius | -2.0 | 32"7 |
| Saturn | 20h07m50s | 20°34'S | Capricornus | 0.5 | 15"4 |
The coordinates above are given in J2000.0. The trio will be at an angular separation of 34° from the Sun, which is in Ophiuchus at this time of year.
The sky on 17 Dec 2020
| The sky on 17 December 2020 | ||||||||||||||||||||||||||||||||||
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11% 3 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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| 02 Aug 2021 | – Saturn at opposition |
| 10 Oct 2021 | – Saturn ends retrograde motion |
Image credit
The Moon in conjunction with Venus and Jupiter, with the Very Large Telescope in the foreground. Image © Y. Beletsky, ESO, 2009.