Jupiter and Saturn closest meeting in centuries on the 21st: get ready!
Artist’s concept of Jupiter and Saturn in December of 2020, as viewed from a space-based perspective. Their conjunction will be December 21. See the moon in this drawing? It’ll be along our line of sight to the planets around December 16, 2020. Chart via Jay Ryan at ClassicalAstronomy.com. Image courtesy of EarthSky.org
The show is on and thrilling to observe!
Everyday this week, within one hour of sunset, in the colorful sky to the southwest, brilliant planet Jupiter and fainter Saturn appear aligned just above skyline. See the two shining, star-like points of light incrementally closer to one another each successive evening. We are witnessing the overture to a phenomenal astronomical moment known as a Great Conjunction of the largest planets in our solar system, Jupiter and Saturn.
For the first time in nearly eight centuries, yes, not since 1226, this “greatest of great conjunctions” will be observable on Monday, December 21, 2020, coinciding, by chance, with the winter solstice. To our eyes, there will be a separation of one-tenth of a degree between the planets, the thickness of a toothpick.
Planetary conjunctions are frequent occurrences, but only Jupiter-Saturn conjunctions bear the name “great conjunction”, because they are infrequent. The two planets arrive at conjunction every 20 years this century, but their orbits have not brought them precisely this close since 1623. That event occurred hidden from view in the sun’s glare, referring us back to 1226 for the most recent great conjunction visible with the naked eye. The two planets will not appear this close again until 2080. (NASA)
Sunset is at 4:29pm today. With an unobstructed view to the southwest horizon, Jupiter will be visible within minutes of 5pm; then, as twilight deepens, find dimmer Saturn above and left of Jupiter. With binoculars, Saturn can be spotted sooner. The pair sets into the horizon by 7pm this evening and 6:50pm on the 21st. See diagram, below, to be guided to the added presence of the crescent moon.
Scout out the best location for viewing, approximately above where the Sun sets.
Wishing you clear skies!
In December, just as Jupiter and Saturn are nearly at their closest, the young moon will sweep past them. From December 16-25, 2020, the planets will be separated by less than a full-moon diameter, just as the moon is passing close. Jupiter is brighter, outshining Saturn by 12 times. Saturn is respectably bright, though, shining as brilliantly as a 1st-magnitude star.
