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 21st. 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.
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.
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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 16th 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.
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!
