“…And behold, the star that they had seen at its rising preceded them, until it came and stopped over the place where the child was. They were overjoyed at seeing the star, and on entering the house they saw the child with Mary his mother.”
Matthew 2: 9-11
Two millennia ago, Scripture tells us that the three Magi – distinguished, learned men from another land – were led to the Christ child by a bright star that their calculations had predicted would rise in the sky over Judea. Was there really a star or other body of exceeding brightness visible at that time?
It might not have been a star, but rather the conjunction of two planets, and the same bright beacon the Three Kings saw on that holy night might be the same light we’ll see this weekend – if the weather is clear.
In the late afternoon, Jupiter and Saturn will appear near the horizon in what is being called the Great Conjunction of 2020. From our vantage point, the planets will appear to merge in the sky, although they will actually be a few hundred million miles apart.
Given the current weather reports, the best opportunity to see the planets will be between 5:30PM and 6PM today (December 18). Look in the southwest sky, near the horizon where the sun went down and you will see not a blazing beacon but a still-noteworthy sight of the two largest planets in our solar system approaching each other.
No telescope needed – you’ll be able to see this with the naked eye. Or, you can check out the livestream by Siena’s Physics and Astronomy Department at siena.edu/physicsyoutube starting at 5:30PM. They will project an image from one of the College’s telescopes, and you’ll be able to see the rings of Saturn and the bands of Jupiter, plus a few of their brightest moons.
The conjunction will actually reach its peak on Monday, but cloud cover is forecast.
“It’s actually impressive to see even a few days before the conjunction, so make time to look for it this evening if the weather is clear,” said Rose Finn, Ph.D., professor of physics and astronomy.
George Hassel, Ph.D., physics laboratory technician, said the planets pass each other every 20 years like runners on a track, but they will appear to be the closest this year than they have since 1226. He created a simulation that was shared on Siena’s social media today.
“It won’t be like the image we see on a Christmas card, but it will still be the brightest object in the southwest sky after sunset.”
Daniel Allspach ’21, who has done study and research with Hassell, compared learning about planetary conjunction in class versus seeing it happen for real.
“Learning about the motion of planets across the night sky in astronomy class felt highly theoretical, since their position does not change much in one night,” he said. “However, the conjunction of Jupiter and Saturn shows the effects of planetary motion playing out in real time. It will be amazing to see.”
So, was there a similar planetary conjunction or other astronomical event at the time of the birth of Christ? Hassel paraphrased Br. Guy Consolmagno, S.J., director of the Vatican Observatory, who has several theories: the first is that it’s just a very nice story. Another is that it was a supernova, but no other cultures recorded such an event two thousand years ago. A comet is a possibility, but at the time they were generally considered to be a bad omen and would likely not have been seen as a harbinger of joy.
The fourth – and most likely theory – was that it was the conjunction of Jupiter and Saturn.
“The Magi were trained astronomers, and the conjunction was something they would have watched for and studied,” he explained. “This kind of event was associated with a king or royalty.”
What does Scripture say about the matter? Fr. Dennis Tamburello, O.F.M., Ph.D., professor of religious studies, refers us to Matthew 2:1-12 for the Biblical text and an explanation in Harper’s Bible Dictionary. Fr. Dennis said the general consensus is that what we call the “Bethlehem Star” or “Christmas Star” was indeed the conjunction of Jupiter and Saturn in the constellation Pisces in 7 B.C.E., having the appearance of a great star. Pisces was considered in astrological traditions a constellation of the Jews.
“Matthew's account is probably a blend of astrological lore and midrashic interpretation of Old Testament texts: ‘a star shall come forth out of Jacob, and a scepter shall rise out of Israel’ (Numbers 24:17) and ‘nations shall come to your light, and kings to the brightness of your rising’ (Isaiah 60:2),” according to Harper’s. “The tradition of a heavenly sign appearing about the time of Jesus' birth was seen by Matthew as a fulfillment of the Old Testament texts, understood as messianic promises, and he related the story to show both the fulfillment of prophecy and the universal significance of Jesus.”
“It appears that the alignment of Saturn and Jupiter on Dec. 21 is the same phenomenon described in Matthew 2,” said Fr. Dennis. "Whether in fact this has a connection with the birth of Jesus is another question."
Fr. Linh Hoang, O.F.M., Ph.D., associate professor of religious studies, notes that there isn't much mention in Scripture about Saturn and none of Jupiter.
“Some people have made the speculation that it may have occurred during Jesus' birth but again there wasn't explicit mention of Jupiter in the New Testament,” he said. “The two planets are named for the days of the week – Thursday and Saturday. But other than that, I’m not sure if we can make a connection to Christianity with it. The Church has tended to shy away from astrology [as opposed to astronomy], which is where the popular conversation about the conjunction of Saturn and Jupiter is heading.”