Jupiter and Saturn haven’t been this visibly close in 800 years – how to look

Saturn, captured here by the Hubble Space Telescope during the summer, will align with Jupiter on December 21st.

NASA, ESA, A. Simon (Goddard Space Flight Center), MH Wong (University of California, Berkeley) and the OPAL team

Get ready for a rare and spectacular show just before Christmas. An event dubbed a great conjunction will happen on December 21, when Jupiter and Saturn, the two largest planets in our solar system, appear very close in the sky. In fact, closer than they have been since the Middle Ages.

The event is so legendary that some have associated it with the famous Star of Bethlehem that guided the three wise men in the biblical story of the Nativity. (For more information on this corner, read below.)

In astronomy, a conjunction occurs when two astronomical objects (asteroids, moons, planets, stars) appear close together in the sky when viewed from Earth. A great conjunction specifically involves Jupiter and Saturn. This only occurs every 19.6 years, so the event is already rare, but the December 21 event will be the closest observable conjunction of the two from the year 1226. (They too occurred so close in 1623, but they probably couldn’t have been seen from Earth.) And don’t miss it: you may not have another chance.

“This is the ‘biggest’ major conjunction between Jupiter and Saturn for the next 60 years, with the two planets not appearing that close in the sky until 2080,” said Preston Dyches, writer and producer at NASA’s Jet Propulsion Laboratory. , in a NASA video.

The December 21 event should be easy to see, says Jeffrey Hunt, astronomy educator and former planetarium director, who wrote about the event on his website, When the Curves Line Up.

“Go out after dark to find (the planets) in the southern sky,” he advises. “Binoculars are useful; the pair is visible to the naked eye as Jupiter passes and passes Saturn. On the evening of the conjunction, the planets enter the eyepiece of an observation telescope or small low-power telescope.”

The rings of Saturn and the four brightest and largest moons of Jupiter will also be visible with the help of binoculars or a telescope.

Those who want to photograph the moment can do it easily. Hunt states that a tripod-mounted camera with exposures of up to 10 seconds can capture planets and stars in the background. The event should be visible from any part of the Earth that offers clear skies.

The conjunction is sometimes referred to as the Christmas star. Some argue that a similar planetary encounter created the legendary Star of Bethlehem which led the biblical Magi, also known as the three wise men, to the Child Jesus. Even the German astronomer Johannes Kepler presented the idea in the 17th century.

But when the facts are investigated, this does not quite correspond.

“Everyone is looking for a great angle,” says Hunt. “The problem with the Star of Bethlehem connection is the actual year and season (or) month of birth. And there are other planetary alignments that could explain the Star of Bethlehem. This topic has been completely beaten to death by the community of Bethlehem. planetarium in the 1980s. “

Don’t look for a sci-fi fusion of Jupiter and Saturn, says Hunt. This is not an eclipse.

“The planets are not going to merge into a single point of light like some media reports,” he says. In other words, Jupiter will not pass directly in front of Saturn, cutting it out of sight.

There’s really no need to beautify the view, as it’s already stunning enough on its own.

Hunt notes that although this particular event is particularly close, he realizes that a great conjunction is a generational event, not a one-time event.

“A great conjunction occurs three or four times in a human lifetime and marks the passing of generations,” he says. “I am encouraging families to take their children out and watch, to tell the children that the planets will be close to each other again in 20 years and to ask how old they will be then.”

Although the planets unite over time, December 21 will mark the actual conjunction – the night when the two planets are closest and Jupiter is very slowly passing Saturn. December 21, of course, also marks the winter solstice in the northern hemisphere and the summer solstice in the southern hemisphere.

If you’re tied up on December 21, you can keep going outside on Christmas Eve to take in the view. The planets will stay comfortably close until December 24th.

Finally, 2020 is giving us something positive to look forward to.