The Great Conjunction of 2020 and The Christmas Star

 by Holly Schubert

You probably have heard that there is an exciting celestial event happening in the night skies in the month of December, culminating on December 21^st. The orbits of Jupiter and Saturn will align so that they will appear very close to each other as we observe them in the sky from earth. This alignment, which happens about every 20 years, is called The Great Conjunction. (Of course, while they appear close to each other from our vantage point here on earth, out in space they are still hundreds of million miles away from each other – a bit like how an airplane can look like it’s close to the sun or moon as it flies through a certain section of the sky.)

Conjunctions between two (or more) planets happen because planets closer to the sun have a shorter orbit and take less time to complete a circle around the sun, and planets further away from the sun have a longer orbit and take a longer time to complete a circle around the sun. So, periodically, the planet closer to the sun, with a shorter orbit, “laps” the planet further away from the sun as they orbit. The planets line up with each other and in relation to earth as they orbit, causing them to come near each other in our night sky. 

Illustration via Guy Ottewell’s blog.

To picture how this happens, you could imagine two model train tracks circling a Christmas tree. The tree is in the center, then track #1 is a small oval close to the tree, then track #2 is a separate larger oval further from the tree, circling around track #1 and the tree. Both tracks have a model train engine on them running at the same speed. If both trains start next to each other, the train on track #1 will make it back to the starting point a little sooner than train #2, because it has a shorter distance to travel. As they continue to circle the tree multiple times, they won’t be next to each other anymore, and train #1 will continue to pull further ahead of train #2. Eventually, after several orbits around the tree, train #1 will catch up to train #2 and they will be side by side each other on their tracks. A similar dance happens with the planets, causing a conjunction. In the case of Jupiter and Saturn, it is roughly every 20 years that Jupiter catches up with Saturn in their orbits around the sun. 

This year’s great conjunction is even more special because of how close Jupiter and Saturn will be in the sky. They will be only 0.1 degree apart, which is about 1/5 the width of a full moon. Because in some years the conjunction is not as close, and in some years the conjunction happens during daylight hours, this is the closest visible great conjunction since the year 1226, almost 800 years ago!

Check out this article from Earth Sky Tonight for great explanations of conjunctions and the history of the Jupiter-Saturn conjunction:

https://earthsky.org/astronomy-essentials/great-jupiter-saturn-conjunction-dec-21-2020

Here in western Pennsylvania, Jupiter and Saturn will be visible just after sunset in the southwest throughout December, including during the great conjunction. 

Saturn (upper left) and Jupiter (bottom right)
at Lutherlyn at about 6:00 pm on December 10, 2020

At Lutherlyn in the coming week or so, they will set behind the true horizon by 7:30 pm, and unless you have a very clear horizon will disappear behind trees or buildings well before that. The best time for us to see them will be between about 5:00 and 6:00 pm. On the 16^th the crescent moon will also be just below the two planets in the evening sky. 

screenshot from Starmap showing position
of Saturn, Jupiter, and crescent moon 
in southwest sky at Lutherlyn 5:00 pm December 16, 2020. 

Each night they will get closer and closer together until their closest point on December 21, and will remain visibly near each other for about another week after that. That is enough days that hopefully SOME evening in that window will have clear skies between 5:00 and 6:00 pm so we can see this amazing sight!

In the Starmap star chart for December 21, 2020
Jupiter and Saturn are so close together they appear to be one object.

.

In order to see Jupiter and Saturn as separate objects on the Starmap star chart for December 21, 2020,
you have to zoom in so far that you can barely see any other stars! 

Because these two planets will be so close together that they will almost appear to be one very bright star, and because this year’s conjunction is happening so close to Christmas, many have been referring to it as the Christmas star. This jogged a memory in me, from Sunday school or something like it as a child – wasn’t something like this conjunction what actually caused the Christmas star?

The Christmas star, or star of Bethlehem, refers to the star that the magi saw that prompted them to search for a new king, and eventually led them to find Jesus. This part of the account of Jesus’ birth is related in the Bible in Matthew, chapter 2. 

Matthew 2:1-2   “After Jesus was born in Bethlehem in Judea, during the time of King Herod, Magi from the east came to Jerusalem and asked, “Where is the one who has been born king of the Jews? We saw his star when it rose and have come to worship him.”

Many people over the years have tried to determine if there is a historical astronomical event that would explain what this star was that the magi saw, and why it was so special that it led them to travel a far distance to worship a new king outside of their own lands. 

Though we often see magi as part of nativity scenes suggesting they were present on the night Jesus was born, it is likely that they arrived to find Jesus later. We’re also not really sure exactly what year Jesus was born, because of the variability of different calendars used throughout history. (The generally accepted range for the year of Jesus’ birth is sometime between the years 6 BCE and 2 BCE.) These factors mean that people have examined a variety of different astronomical events in different years as possible explanations for the star that led the magi to travel to Palestine to pay homage to a new king.  There are many possibilities!

Various supernovas, comets, and planetary conjunctions that took place in the proper range of years have been suggested to be the explanation for the Christmas star. (In ancient times, all objects in the night sky other than the moon were referred to as stars, even when observers knew they were objects that behaved differently than stars, like comets and planets.) The Christmas star may have been a night sky object as unusually rare and bright as the Jupiter-Saturn conjunction we are witnessing this year. Or it might have been a more ordinary looking star that carried meaning because of its position in the sky. See this article in Space.com for a nice summary of some of the historical astronomical events that people have suggested may explain the Christmas star (and an interesting snapshot of the tradition of planetarium shows on the topic):   

https://www.space.com/14036-christmas-star-bethlehem-comet-planet-theories.html

Not everyone agrees that what is described in Matthew 2 has a historical astronomical explanation. Some support the idea that the Christmas star must have been a miraculous appearance, rather than a natural one. Some find it more meaningful that Jesus’ birth would be signaled by something miraculous or beyond-natural than by something a part of the natural world. Others point to how unlikely it is that a natural star could lead travelers from so far away to a specific dwelling in a specific town, leading them to believe the “star” that the magi followed was some other kind of light put in the sky by God for that purpose. 

 Mosaic mural depicting the Nativity by Manuel Perez Paredes
in the Nuestro Señor del Veneno Temple on Carranza Street in Mexico City

creative commons license  https://creativecommons.org/licenses/by-sa/3.0/deed.en

Another possibility is that Matthew’s description of the star was not intended to be understood literally. Maybe it was at least partly poetic, a good way to get a point across that creates a certain understanding or feeling. We know that there are different types of literature in the bible, and that they have different purposes. We know that some of it is poetry. We know that some of it is history. Other parts of the bible include prophetic messages, letters, laws, and more. All of them are meant to be taken seriously as meaningful expressions about God and God’s people, but not all of them are meant to be taken as factual descriptions of literal happenings. Gospels are meant to tell the story of the life of Jesus in a way that communicates the importance of who Jesus was and is, so that people living after Jesus can know him and follow him.

The way that Matthew’s gospel describes the life of Jesus makes many references to Jewish scripture, prophecy, and miraculous happenings, making it clear that Jesus is closely intertwined with the history, faith, and tradition of the Jewish people. Matthew wants us to know that Jesus comes out of this tradition and carries out this tradition to its fullest. The first people to read Matthew’s gospel would have been familiar with the idea of a star associated with the birth and rule of a king, and with dignitaries from the east seeking an audience with a current ruler. They also would have seen the magi representing the wider non-Jewish world, signaling that Jesus extends God’s love and salvation beyond the called people of Israel to the whole world. This would have been a meaningful way to communicate the importance of Jesus to the whole world, right from his youngest days as a child on earth. For those of us who are Christians, believers, and followers of Jesus, we know that enough of the history of Jesus’ life on earth is true to confirm what we have come to know in our own lives and in our own hearts – that Jesus, the son of God, is our salvation and redemption and our example and ultimate expression of God’s love.

To me it is thrilling to think that Jesus’ birth may have been accompanied by an astronomical event as stunning and exciting as the one we are seeing this December! It may well be that something like this took place then, and it is fascinating to comb through the history and research to find information on the possible explanations.

The beauty and delight of witnessing something like Jupiter and Saturn so close together that they appear as one super-bright star in the sky is a reminder of the power, beauty, joy, and love of God as creator of all our worlds. And the association of this event with a similar event connected with the birth of Jesus is a reminder that God has chosen to be astonishingly present and very much a part of this world that God has made, and to keep drawing us closer and closer to God through Jesus. Regardless of what kind of light accompanied Jesus’ birth and the magi’s journey, we can see for ourselves that the words of Psalm 19 are true:

Psalm 19:1-4

The heavens declare the glory of God; the skies proclaim the work of his hands. 

Day after day they pour forth speech; night after night they reveal knowledge. 

They have no speech, they use no words; no sound is heard from them. 

Yet their voice goes out into all the earth, their words to the ends of the world.

The same God who made all the universe, all the stars and planets and their orbits, also made you and loves you. It is a joy and a blessing to be a part of God’s wondrous creation!