The rare planetary trio of Mercury, Jupiter, and Saturn graces the evening sky. In today’s article, we will tell you how, when, and where to see this spectacular astronomical event and explain why it is so special.
What is a planetary trio?
As the definition indicates, a planetary trio is formed by three planets that fit within a circle with a diameter of less than 5 degrees. In this case, binoculars will come in useful as typical binoculars have a field of view of 5 degrees or more. The planetary trio of Mercury, Jupiter, and Saturn in January will be the first of two planetary trios that will take place in 2021: the second one falls on February 13, 2021, when Mercury, Venus, and Jupiter will gather in the morning sky.
Moreover, it is the first of four planetary trios that will occur in the decade covering the period from January 1, 2021, to December 31, 2030. The skywatchers will also have a chance to view the beautiful dance of three planets — Mercury, Mars, and Saturn — on April 20, 2026. Finally, the last planetary trio of the decade will take place on June 16, 2028: this time, it will consist of Mercury, Venus, and Mars.
How and when to see the planetary trio of Mercury, Jupiter, and Saturn?
For the first time since October 2015, the observers have an opportunity to witness a planetary trio on January 8–11, 2021: see Mercury, Jupiter, and Saturn shining close to each other low in the evening sky. To get a better view of these planets, find an unobstructed horizon, and start your observation no later than 45 minutes after sunset. Unfortunately, sunset afterglow might interfere with observation, outshining the planets — use binoculars to spot them.
The sensational great conjunction of Jupiter and Saturn took place on December 21, 2020; even after this day, the gas giants remain close to each other. The swift planet Mercury will join Saturn on January 9, 2021: their conjunction will occur at 4:14 p.m. EST (21:14 GMT) in the constellation Capricornus. Mercury will shine at a magnitude of -0.9, while the ringed planet Saturn will be at a magnitude of 0.6. Soon thereafter, on January 11 at 06:06 a.m. EST (11:06 GMT), Mercury will make a close approach to radiant Jupiter, whose magnitude will be -1.9.
Mercury, Jupiter, and Saturn will appear at their closest on January 10, 2021, at 2:00 p.m. EST (19:00 GMT). The planets will fit within a circle with a diameter of 2,5 degrees. You will be able to enjoy this spectacular trio for several days to a week, depending on your field of view. Then Mercury will gradually soar to its greatest eastern elongation on January 24, 2021, and will be perfectly observable in the coming weeks. Meanwhile, the gas giants Jupiter and Saturn will soon disappear from the evening sky.
The easiest way to find Mercury, Jupiter, and Saturn in the sky above you is to use the Star Walk 2 app. The stargazing guide will also help you check the rise and set times for the planets, determine the best viewing time for your location, and enjoy the stars and constellation surrounding them.