Just before Christmas, get ready for a rare, spectacular sight. An event known as the great conjunction will take place on December 21st, when Jupiter and Saturn, the two largest planets in our solar system, appear very close to the sky. Closer than since the Middle Ages.
The event is so legendary that some have linked it to the famous Star of Bethlehem who directed the three wise men in the Bible’s nativity story. (See below for more information on this angle.)
In astronomy, a conjunction occurs when any two astronomical objects (asteroids, moons, planets, stars) appear close together in the sky when viewed from Earth. A great connection concerns Jupiter and Saturn specifically. This only occurs every 19.6 years, so the event is already rare, but the December 21st event will be the closest observable link between the two since 1226. (They got this close too in 1623, but probably couldn’t be seen from Earth.) And don’t miss it – you may not get another chance.
“This is the ‘greatest’ great connection between Jupiter and Saturn for the next 60 years, with the two planets not appearing that close to the sky until 2080,” Preston Dyches, a writer and producer at NASA’s Jet Propulsion Laboratory, told NASA -Video.
The December 21st event should be easy to see, says astronomy educator and former planetarium director Jeffrey Hunt, who posted about the event on his website When the Curves Line Up.
“Step outside after sunset to find (the planets) in the southern sky,” he advises. “Binoculars are helpful. The pair can be seen with the naked eye as Jupiter overtakes Saturn and passes. On the evening of the connection, the planets with low power fit into the eyepiece of a spotting telescope or a small telescope.”
The rings of Saturn and the four brightest and largest moons of Jupiter can also be seen with the help of binoculars or a telescope.
Those who want to photograph the moment can easily do so. According to Hunt, a camera mounted on a tripod can capture the planets and background stars with an exposure of up to 10 seconds. The event should be visible from anywhere on earth where the sky is clear.
The conjunction is sometimes referred to as a poinsettia. Some claim that a similar planetary meeting created the legendary star of Bethlehem that led the biblical kings, also known as the three wise men, to the Christ Child. Even the German astronomer Johannes Kepler got to the heart of the idea in the 17th century.
But when you dig into the facts, they don’t quite agree.
“Everyone is looking for a fantastic angle,” says Hunt. “The problem with the connection to the Star of Bethlehem is the actual year and season (or month) of birth. And there are other planetary orientations that could explain the Star of Bethlehem. This subject was thoroughly beaten to death by the planetarium community in the 1980s. “
Don’t look for a fusion of Jupiter and Saturn with science fiction films, says Hunt. This is not a solar eclipse.
“The planets will not merge into a single point of light, as reported in some media,” he says. In other words, Jupiter does not go right in front of Saturn and cut it out of view.
There’s really no need to embellish the sight as it is amazing enough on its own.
Hunt notes that while this particular event is particularly close, it is recognized that a great conjunction is a generational event, not a one-off.
“A great conjunction occurs three or four times in the course of a human life and marks the death of generations,” he says. “I encourage families to take their children outside, tell them the planets will be close together again in 20 years, and ask how old they will be.”
Although the planets come together over time, December 21st marks the actual conjunction – the night when the two planets are closest and Jupiter very slowly passes Saturn. Of course, December 21st also marks the winter solstice in the northern hemisphere and the summer solstice in the southern hemisphere.
If you are tied up on December 21st, you can go outside until Christmas Eve to marvel at the sight. The planets will stay comfortably close until December 24th.
2020 will finally give us something positive to look forward to.