Yuletide stargazers in the Northern Hemisphere can see Saturn and Jupiter lined up closer than any time since 1623.
Unseen for 400 Years, “Christmas Star” to Grace Night Skies on December 21
LONG BRANCH, New Jersey—For the first time in nearly 400 years, a conjunction of Jupiter and Saturn will occur.
The two planets will be so close together on Dec. 21, they will form what many have dubbed the “Christmas Star” of 2020. But next week will mark a rarity: They have not been this close since 1623, but the event was too close to the sun to see.
“Jupiter and Saturn will align in the sky, something that happens every 20 years or so. This one is special in that it is very close, only about 1/5 the diameter of the full moon,” Patrick Hartigan, Rice University astronomer and professor of physics and astronomy, said in an email to Zenger News.
The alignment in 1623 wasn’t observable, said Hartigan, who has written extensively on this conjunction. It has been 800 years since the phenomenon was seen.
“The last time anyone has seen them this close together was in March of 1226,” he said.
In news stories and across social media, the conjunction has been referred to as the “Christmas Star,” with some making references to the Star of Bethlehem. Its occurrence four days before Christmas this year has led to speculation about a religious meaning.
Jesuit Brother Guy Consolmagno, director of the Vatican Observatory, told Zenger News the planets will be so close this time, it won’t be possible to differentiate them.
“If you look to the west soon after sunset, you will see what looks like a bright star — actually, the planet Jupiter — and just above it a fainter yellow star, which is planet Saturn. Over the next few days they will slowly move closer together until on Dec. 21, they will actually be so close that your eye won’t be able to tell them apart,” he said.
The Catholic priest and astronomer said some are comparing this conjunction with the Star of Bethlehem.
“Some people draw an analogy between this event and the Star of Bethlehem, but there are so many different possible explanations for the star we can’t say for certain that any of them are what Matthew was writing about. But of course, Matthew wasn’t writing about the star; he was writing about the baby,” Consolmagno said.
“There is no direct religious significance,” he said, “except to remind ourselves that God has given us a universe that is both beautiful and also subject to His laws, the laws of science, which allow us to predict beautiful events like this conjunction.”
Professor Nahum Arav, a physics professor at Virginia Tech and an expert in “the influence of super-massive black holes” added that some are calling it a “Christmas Star” because “of the Star of Bethlehem that was in the Scripture around the time Jesus was born, and now the star appears on Dec. 21, very close to Christmas. So the link is being made that it would be the Christmas Star.”
NASA, however, is referring to the occurrence as the “Great Conjunction,” a term originally coined by 17th-century German astronomer Johannes Kepler.
“Great conjunctions played a very significant role in Kepler’s life,” historian Thony Christie told Zenger News, adding that during “the so-called Star of Bethlehem, the men from the east, who according to Matthew 2:2 followed the star, were, in the original Greek, Magoi (Latin/English Magi) and this means they were astrologers and not the sanitized wise men or kings of the modern storytelling.”
“Kepler would have been well aware of this,” Christie said. “This led Kepler to speculate that what the Magi followed was an important astrological occurrence and not a star in the normal meaning of the word. One should note that in antiquity, all visible celestial objects were stars … so interpreting the Star of Bethlehem as an astrological occurrence was not a great stretch.”
Dr. Adam Mosley, an associate history professor at Swansea University added that Kepler “didn’t claim the Star of Bethlehem might have been a conjunction of Saturn and Jupiter. He did, however, claim that such a conjunction might have presaged the event witnessed by the Magi, which he thought was a nova.”
While the conjunction will be observable around the world, Hartigan said it will be more visible closer to the equator. “In the U.S., it will be above the western horizon 15-20 degrees or so for most of us,” he said. “It will be about as bright as the Dog Star (Sirius), the brightest star in the night sky. Then there will be a very faint object, Saturn, right next to it.”
He suggested those who want to see it should go where the sunset can be viewed and wait for it to get dark. An optimal viewing area would be a place with a good horizon without a lot of buildings and trees around.
“It won’t look like a star; it will look like a reasonably bright object with a much fainter one next to it,” he said. “The closest approach is on Dec 21. It will still be close on Christmas, but not as close.”
“It’s been nearly 400 years since the planets passed this close to each other in the sky, and nearly 800 years since the alignment of Saturn and Jupiter occurred at night, as it will for 2020. That allows nearly everyone around the world to witness this ‘great conjunction,’” Henry Throop, astronomer in the Planetary Science Division at NASA Headquarters, said.
“Jupiter and Saturn are so bright, in fact, that they are visible even from city lights,” he said. “Folks just need to have a clear view of the southwestern horizon about an hour after sunset.”
For thousands of years, “people have had a strong connection to events in the sky. Modern historians and astronomers have identified many cosmic events that can be tied to culture or religion,” he noted before describing a 7 B.C. conjunction between Saturn and Jupiter.
“People at the time could have observed and been inspired by this or other celestial events, such as a comet, a supernova or an alignment between the stars and planets,” he said.
The next conjunction will occur in 2040, according to Throop, but it will take until 2080 for there to be a very small separation of 0.1 degrees between Jupiter and Saturn again, as there will be on Dec. 21.
“Matthew’s goal in telling this story is more theological than it is historical,” said Francesca Stavrakopoulou, a professor of the Hebrew Bible and ancient religion at the University of Exeter. “But Matthew would likely be pleased with the awe it inspires in those who anticipate it.”
(Edited by Carlin Becker and Fern Siegel)