Get ready for December 21, 2020, when Jupiter and Saturn ‘winter solstice great interconnection’ brings them closest to the night sky since 1623
December 21, 2020
Tonight, stargazers around the world are treated to an event that only happens once every 19.6 years on average. December 21, winter solstice, Jupiter and Saturn appears in the same place in the night sky in an event called a large context.
These two so-called gas giants from ours solar system, which is usually bright enough to see with the naked eye even from a city’s light – polluted heart, will be adjusted, seen from the ground, to look like an extremely bright planet. This year, the pair will be only 0.1 degrees apart in the sky, making it the closest such event since 1623. For reference, the diameter of the full moon in the sky spans about 0.5 degrees, as we see it from Earth. The next time these planets will be visible so close together in the night sky, it will be the year 2080.
Jupiter and Saturn are the most distant of the planets that can be easily seen with the naked eye. Uranus is only visible in this way in particularly dark skies, and you always need binoculars or a telescope to see Neptune.
Because Jupiter and Saturn are furthest from the sun on all planets with the naked eye, they orbit slowly. It takes almost 30 years for Saturn to take a shot of the sun, while Jupiter takes about 12. This is why connections between the two are the rarest of them between all the easily visible planets.
Where to look for the big picture
While the event itself takes place on December 21, the planets will be close to the sky in the days leading up to it and beyond. To see the context, look south-west as soon as the sun goes down and find the brightest thing you can see. As the timing coincides with the winter solstice, the shortest day of the year in the northern hemisphere, the sunset will be early. Jupiter and Saturn will be low in the sky and set quickly, so make sure you have a good view of the western horizon to catch them.
If you have binoculars available, the two will be visible as separate planets. Saturn will be above and to the left of Jupiter in the northern hemisphere and below and to the right in the southern hemisphere.
But if your binoculars are powerful enough, a minimum magnification of seven, you can even get an overview of Jupiter’s four Galilean moons. In the northern hemisphere, two of these, Callisto and Ganymede, will be to the left of Jupiter. To the right of Jupiter, much closer to the planet, you could see Io and Europa. In the southern hemisphere, the moons will stand in the opposite direction of this.
For stargazers with a telescope, if you can see the planets before they dip too low in the horizon, the view will definitely be worth it, and it’s not something you’ll be lucky enough to see often: Saturn, its rings and some of its moons along with Jupiter, its great red spot and Galilean moons, all visible at once.
What you need
A clear sky
A telescope (optional)
Stargazing at home is shown every four weeks
These articles are published weekly at newscientist.com/maker
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