As the year 2020 has had one unusual occurrence after another, it seems fitting that the year will end with another extremely rare event — what astronomers say is a “triple conjunction” of planets, which will perhaps be another rendition of the Star of Bethlehem, which is said to have shone when Jesus Christ was born.
Just before Christmas this year, on December 21, the world will be treated to a sight that has not been seen by human eyes since the early Middle Ages, when the planets Saturn and Jupiter will align, making a beautiful bright “star” in the night skies.
The Bible’s Gospel of Matthew says that an exceptionally bright star appeared in the skies after the birth of Jesus Christ and the wise men followed it to find him.
But in actuality, was this really a comet? A supernova exploding in another part of the universe? Or was it a conjunction of two planets?
Whatever it was that appeared in the skies two millennia ago, next Monday, December 21, on the winter solstice, there will be another “great conjunction,” when Jupiter and Saturn appear from our perspective to pass each other very closely.
A conjunction denotes the apparent passing of two or more celestial bodies, but a “great conjunction” always refers to the planets of Jupiter and Saturn.
Jupiter and Saturn actually engage in a great conjunction — as we see them — every 19.85 years. This occurs naturally since Jupiter takes 11.86 years to orbit the Sun and Saturn takes 29.4 years, which means they appear to pass each other from our point of view.
Despite these large planets being many millions of miles distant from each other, their combines shine makes for a very remarkable sight.
The sight next Monday night will be extraordinary, as the two planets, each usually visible with just the naked eye, will “combine” their light and look like a “double planet,” something that hasn’t been seen since March 4, 1226, according to astronomer Patrick Hartigan from Rice University.
“Alignments between these two planets are rather rare, occurring once every 20 years or so, but this conjunction is exceptionally rare because of how close the planets will appear to be to one another,” Hartigan explains in an interview with Forbes.
“You’d have to go all the way back to just before dawn on March 4, 1226, to see a closer alignment between these objects visible in the night sky,” the astronomer said in a statement.
The spectacular sighting, providing what promises to be an unforgettable experience for stargazers, will be viewable from anywhere on earth, but will be most easily seen with a telescope.
“The planets will appear low in the western sky for about an hour after sunset as viewed from the northern hemisphere, and though they’ll be closest on December 21, you can look each evening that week,” Hartigan says.
Although the aligned planets will be sinking toward the horizon, making them more difficult to see because of light pollution, the phenomenon will still be bright enough to be viewed at twilight. All you need, the astronomer says, is “an unobstructed view to the southwest, and to look to the southwest from about 45 minutes after sunset where you are,” he states.
To catch the spectacular phenomenon in the night sky at its best, stargazers might want to use a regular telescope. For a brighter view, an astronomer’s telescope or a university telescope feed would be even better.
The Forbes article says that alignments like these, called “planetary conjunctions,” are not necessarily rare, but some of them are impossibly rare or only come around once every several hundred years.
Astronomers have long speculated that the Star of David written of in the Biblical book of Matthew, was an exceptionally rare triple conjunction between the planets Saturn, Jupiter, and Venus. One such astronomer was the brilliant Johannes Kepler, one of the greatest astronomers of all time.
Interestingly, the great conjunction during the 2020 solstice will occur seven weeks after Saturn and Jupiter experienced a heliocentric conjunction, when they aligned with each other and the Sun itself.
It is not a secret to astronomers who have recorded their observations for thousands of years that Jupiter and Saturn conjunct every twenty years — even that this occurs in the same portion of the sky approximately every 800 years.
But it seems strange, and perhaps a bit more meaningful, this time around, with the next great conjunction occurring on the date of the December Solstice — just four days before Christmas Day.
The planets will appear to be a mere 0.1º away from each other, appearing to be one large star in the night sky to the southwest, approximately 15 degrees up from the horizon. Sky & Telescope magazine says that this is about the width of a toothpick held at arm’s length.
To any armchair stargazer, this will look like one star, and it is a major one that won’t be forgotten for some time.
It will be a result of the closest great conjunction since July 16, 1623 and the first to be easily observable by the naked eye since March 4, 1226.
So is this really what happened back two thousand years ago, as it is recorded in the Gospels?
Great conjunctions occur only about every 300 years and astronomers have calculated previous great conjunctions of Jupiter and Saturn that did in fact happen around the same time as the birth of Jesus Christ.
One popular theory goes all the way back to Johannes Kepler, one of the most brilliant figures of the scientific revolution in the 17th century. The Dutch astronomer was the first to correctly explain the motion of the planets in the heavens.
Nigel Henbest, author of Philip’s 2021 Stargazing Month-by-Month Guide to the Night Sky in Britain & Ireland, states “Kepler thought that the star of Bethlehem was a triple conjunction of Jupiter and Saturn.”
“Here we are two millennia later and a similar conjunction is about to happen within four days of Christmas Day … maybe a new Messiah is about to be born!”
In 1603, when he himself observed a (less visible) great conjunction, Kepler posited that a triple conjunction of Jupiter and Saturn occurred in the year 7 BC. He called it a triple conjunction because as Jupiter laps Saturn in the Solar System, the two planets align with the Sun for a moment.
However, from the Earth’s faster-moving point of view, the planets actually appear to go backwards for some weeks. This is just a relative observance from where we are looking at it, but this retrograde motion can cause two or, in the case of the year 7 BC, three conjunctions in one year.
Astronomers note that the last triple great conjunction occurred in the skies in 1980 and the next one will shine for us in the year 2239.
It seems quite plausible that Jupiter and Saturn were mistaken for a single star back in the time of Christ’s birth. And all around the world, celestial events, such as comets, have always portended certain events.
Even the Bayeux Tapestry, the record of the Norman Invasion of Britain in 1066, shows the appearance of Halley’s Comet occurring that night, which was viewed (by the British anyway) as an especially ill omen.
But stars have always been used for navigation by every culture on the globe, and the Star of Bethlehem stood out to the Gospel writers as an especially meaningful event which showed the path toward a new way of looking at the world.
However you view it, next Monday’s great triple conjunction of Jupiter and Saturn will be a historic event that you must try to view, if at all possible, in the wintry sky. Even if it is cloudy next Monday night where you live, the phenomenon will be visible just fifteen degrees up from the horizon in the southwestern sky 45 minutes after sunset for several days before and after December 21st.
You will get to see two distant worlds become one — shining their very special light on this most difficult of all years that we have ever experienced in our lifetimes.