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The naked eye – Saturn and Jupiter

By Jules-Pierre Malartre


Giant planets Jupiter and Saturn on December 21 during their closest conjunction since the Middle Ages. The planets will be so close they’ll appear as a single bright star in this simulation.

The progressively colder weather of late fall offers some of the clearest skies for observing the wonders of the night sky – cold temperatures steady the atmosphere so there are fewer perturbations. The result: the moon, planets, and other celestial bodies appear clearer in binoculars and telescopes and even to the naked eye. Winter serves up the steadiest conditions actually, but very few amateur astronomers are brave enough to stand idly in their backyard to gaze at the moon in the sub-zero temperature of January and February.

Saturn and Jupiter conjunction

Late December this year will be a great time to witness a rare astronomical occurrence. The December 21 night sky will play host to a conjunction of the two largest planets in our solar system – Saturn and Jupiter. A conjunction is an event when a number of astronomical objects appear very close in the sky. They might still be very distant in reality, but to the naked eye, they appear to have a get-together in the sky. Such events between Jupiter and Saturn are quite rare as these two giant planets only meet like this once every 20 years or so. Then, it might be worth stepping outside in the cold to observe this. The actual conjunction will take place on December 21, but you can see the two planets getting closer every night during the weeks leading up.

Visible to the naked eye

You don’t need a telescope or binoculars to enjoy watching this conjunction. If you look in a general south-western direction (around where the sun sets) in the very early evening sky (right after sunset), you will see two bright ‘stars’ fairly close to each other. They will be at their closest on that date, but they will be fairly low on the horizon; so it’s worth observing them a few nights in a row in late November and early December as they get progressively closer. This week offers a good opportunity to see them fairly close to each other while being a bit higher in the sky and therefore easier to see (and it won’t be as cold).

Jupiter’s moons

If you have access to a small telescope or good binoculars, you will be able to observe some features of both planets. Even with the smallest telescope or low-powered binoculars, you will be able to see some of Jupiter’s moons. You might spy up to four of them, actually. They are named Io, Callisto, Europa and Ganymede; Callisto, Io and Ganymede will be on one side of Jupiter (Ganymede being the closest, Callisto the furthest from Jupiter), while Europa will be alone on the other side of the giant planet. Seeing Saturn’s rings is a bit more challenging, but some modest equipment will still give you a glimpse of the rings.

A conjunction of these two planets happens only a few times in a person’s lifetime, and this one is especially noteworthy since the two planets haven’t appeared to be this close since the Middles Ages. So it might be worth braving the cold weather to step outside and view this spectacle.