The great conjunction of Jupiter and Saturn: how to see the ‘Christmas star’

Skywatchers, get ready for an exceptional and spectacular view on Monday. In an event called a grand conjunction, Jupiter and Saturn, the two largest planets in our solar system, will appear very close to each other. Closer, in fact, than 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. (To learn more about that angle, read below.)

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 grand conjunction specifically involves Jupiter and Saturn. This occurs only every 19.6 years, so the event is already rare, but the December 21 event will be the closest observable conjunction of the two since 1226. (They also occurred this close in 1623, but probably could not be seen from Earth). And don’t miss out, you may not get another chance.

“This is the ‘greatest’ great conjunction between Jupiter and Saturn for the next 60 years, and the two planets won’t appear that close in the sky until 2080,” said Preston Dyches, writer and producer for NASA’s Jet Propulsion Laboratory, in a Video from NASA.

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

“Get out after sunset to find (the planets) in the southern sky,” he advises. “A binocular is useful; the pair is visible to the naked eye when Jupiter reaches and passes Saturn. On conjunction night, the planets fit into the eyepiece of a spotting scope or a small telescope at low power.”

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

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

The conjunction is sometimes known as the Christmas star. Some claim that a similar planetary gathering created the legendary Star of Bethlehem that led the Biblical Magi, also known as the Three Wise Men, to Baby Jesus. Even the German astronomer Johannes Kepler proposed the idea in the 17th century.

But when you dig into the facts, that doesn’t quite match up.

“Everyone is looking for a fantastic 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 issue was completely hit by the planetarium community. in the 1980s. “

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

“The planets will not merge into a single point of light as reported in some media,” he says. In other words, Jupiter will not pass directly in front of Saturn, out of sight.

There really is no need to beautify the view as it is amazing enough on its own.

Hunt notes that while this particular event is remarkably close, keep in mind that a grand conjunction is a generational event, not a once-in-a-lifetime one.

“A great conjunction occurs three or four times during human life and marks the passing of generations,” he says. “I’m encouraging families to take their children outside to look, tell them that the planets will be close to each other again in 20 years and 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 passes very slowly to 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 hanging out until Christmas Eve to marvel at the view. The planets will stay comfortably close until December 24.

Finally, 2020 gives us something positive to look forward to.