Kepler and the Christmas Star

As the clouds over Prague lifted on the night of October 17, 1604, Johannes Kepler was surprised to observe a new star. He had been waiting to see a rare conjunction of Jupiter, Saturn and Mars which fell into the “Fiery Trigan” of the zodiac (Aries, Leo and Sagittarius). It was in this region that the new star was located: between Jupiter and Saturn in the foot of the constellation of the Serpent Bearer, Ophiuchus. Kepler was able to make observations of this new star for a year before it finally faded from view.

Looking backward, we know what Kepler observed was a super nova (SN1604) – the explosive death-throws of a massive star. At the time, however, nobody knew what these astronomical phenomena were or where they came from.  This new star appeared in the middle of a conjunction, and some wondered if it was actually caused by the conjunction itself. If so, it would be of great astrological and astronomical significance.

In his 1606 pamphlet about this event, De Stella Novo, Kepler considered the possibility that this new star could be likened to the star mentioned in the gospel of Matthew. By Kepler’s calculations, the conjunction phenomenon in which SN1604 appeared occurs about every 805 years. That would place this conjunction near the time of Christ’s birth, so Kepler reasoned this conjunction could have been the cause for the appearance of a similar “new star” at that time as well.

Illustration from Kepler’s De Stella Novo (1606) showing the location of the “new star” (marked “N”)

However, using triangulation data, Kepler knew that this new star was out among the fixed stars, and would not have been useful in guiding the magi as is described in the gospel. For instance, the Christmas star helped lead the magi from Jerusalem to Bethlehem (a mere ten miles away), where the star “came to rest over the place where the child was” (Matthew 2:9). As reported by Burke-Gaffney, Kepler wrote in 1614, “This star was not of the ordinary run of comets or new stars, but by a special miracle moved in the lower layer of the atmosphere.” Kepler suggested the conjunction and new star may have served as harbingers of this event, but could not be reconciled as the guiding star of the Magi.

Kepler forcefully argued for naturalistic explanations of the things in the heavens, but he was able to recognize that the phenomena of a “new star” would not qualify as the star in the gospel story. The value of studying the world in terms of natural laws is not to explain away the supernatural, but to better help us recognize it. Natural laws become the backdrop for God’s special activities – things that happen beyond what would be expected by natural laws. Our awareness of what is normally expected as a result of natural laws helps us to detect God’s intervention. C. John Collins helps us here with his definitions of the natural and supernatural:

Natural: God made the universe from nothing and endowed the things that exist with natural properties; he preserves those properties, and he also confirms their interactions in a web of cause-and-effect relations.

Supernatural: God is also free to “infuse” special operations of his power into this web at any time, e.g. by adding objects, directly causing events, enabling an agent to do what its own natural properties would never have made it capable of, and by imposing organization, according to his purposes.

Despite Kepler’s analysis over 400 years ago, people still try to associate various “new star” appearances (e.g. those recorded in 7 and 5 B.C.) with the Christmas star. Others try to point to astronomical convergences or astrological ponderings. The Christmas star, however, defies a naturalistic explanation. But isn’t that the point of the whole story? The Christmas story is filled with angelic visits, unexpected pregnancies and divine appointments. It is about the incarnation – the eternal God becoming flesh and dwelling among us. Why should we think the Christmas star ought to fall into some different category?

Since the advent of Darwinian evolution, there has been a move in western culture to distance God from His creation, and insist on naturalistic explanations for everything in our universe. Skeptics look upon the events in the Christmas story as fantasy because they make the unjustified assumption that everything must be explained according to natural laws. Insistence upon naturalistic explanations for the Christmas star – either by astronomy or astrology – are attempts to erase God and his intervening activity from history. It is an effort to reduce the Christmas story to merely a human story rather than a God story. Let us not make that mistake. Let us be like Kepler, and see the Christmas star for what it really was.

Works Cited

Burke-Gaffney, W. 1937. “Kepler and the Star of Bethlehem”. Journal of the Royal Astronomical Society of Canada, Vol. 31:417

Collins, C. John. “How to Think about God’s Action in the World,” In Theistic Evolution: A Scientific, Philosophical, and Theological Critique, edited by J. P. Moreland, etal. Wheaton, Ill: Crossway, 2017.

De Stella Novo image obtained from:

2 thoughts on “Kepler and the Christmas Star

  1. Did you know there is a conjunction of Jupiter, Saturn and Mars forming in the “Fiery Trigan” (Sagittarius) this coming March? Jupiter and Saturn then spend the rest of 2020 in synchronized retrograde loops with a 6’ separation encounter on the winter solstice. Grand finale is Jupiter and Saturn being joined by Mercury, the trio together moving into Capricornus. Does that count as Fiery Trigan conjunctions? I think Kepler would enjoy our God’s marvelous display this year.


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