5 Possible Scientific Explanations for the Star of Bethlehem

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As each Christmas season approaches, the Bible story of the birth of Jesus is retold anew. Amidst the parable, one particular event stands out in the minds of those of us who watch the night sky; the Star of Bethlehem, mentioned in the Gospel of Matthew Chapter 2 as “a star in the east” which led the three wise men on a pilgrimage to Bethlehem. The appearance of the star was said to have fulfilled a prophecy from the Old Testament put forth in the Book of Numbers of the birth of the Messiah … but what was it? Do any astronomical events match the description in the scriptures, and could we link Jesus’ birth to a historical date? Following are astronomical phenomena that provide tantalizing comparisons to that famous star.

5. A Supernova

Could the three wise men have been drawn to Bethlehem by a supernova?

Supernova SN 2006gy illustration, 2006; NASA/CXC/M.Weiss

A supernova explosion occurs when a star much more massive than our Sun nears the end of its life and can no longer support hydrogen-helium fusion. Such an explosion can briefly equal the light and energy output of all the stars in our galaxy combined. While supernovae occur daily somewhere in our universe, a supernova in our galaxy visible to the naked eye only occurs on average every few centuries. The Chinese recorded a supernova in Taurus in 1054, and the last supernova observed in our galaxy was Kepler’s Star in 1604. A supernova is an exotic event that would have appeared as a new star along the plane of our galaxy and surely would have given the Magi pause. Arthur C. Clarke used this hypothesis for the basis of his science fiction short story The Star, in which explorers discover an alien civilization that became extinct during a supernova event that would have been visible from Earth during the time of Christ. While the ancient Chinese recorded what might have been a supernova in the constellation of Capricornus in 5 BC, no supernova remnant has been identified as a prime suspect to be the Star of Bethlehem.


4. A Planetary Conjunction

Some astronomers believe a close pairing of Jupiter and Venus provided the Star of Bethlehem.

Planetary conjunction with moon, December 2009; ESO/Y. Beletsky

The Magi were almost certainly astrologers who noted alignments of the planets as they moved about the zodiac. Such pairings are not at all rare; for example, a close pairing of the two brightest planets, Jupiter and Venus, occurs on March 15, 2012. Still, it has been proposed that the Magi were at least in part motivated by an especially auspicious alignment of the planets. Legendary astronomer Johannes Kepler promoted the concept of a close conjunction of Jupiter and Saturn in the year 7 BC as being the star mentioned. Intriguingly, this pairing also occurred very near the spring equinoctial point in the constellation of Pisces the Fishes, a sign of the zodiac long associated with Christianity. It’s worth noting some scholars believe Jesus was born in the spring, although the exact date, month or even year of his birth cannot be established.


3. A Planetary and Bright Star Conjunction

Could the bright star Regulus have played a role as the Christmas Star?

Photo credit: Anneka/Shutterstock.com

In addition to planetary pairings, several bright stars lie along the path of near the ecliptic that the Sun, Moon and planets trace out in their apparent motions across the sky. One intriguing possibility for the Star of Bethlehem is a very close triple pairing of Venus, Jupiter and the bright star Regulus on June 17, 2 BC. (incidentally, the Latin translation for Regulus is “The Little King”). This was first proposed by science writer Roger Sinnott in Sky & Telescope magazine in 1968, but does have some issues. It’s believed from historical records that King Herod died in 4 BC, before the conjunction occurred. (Scholars believe Christ was born sometime between 8 and 4 BC.) Also, the event would have been visible in the dusk skies to the west, not the east. Another possibility is an occultation of Jupiter by the Moon in the constellation of Aries in 6 BC. This occurs when the Moon passes in front of a planet or star. However, this particular occultation would have been tough to observe, owing to its proximity to the Sun.


2. A Comet

A comet could have been the bright star that drew the Magi to Bethlehem.

Comet Hale-Bopp, 1997; Philipp Salzgeber

The idea that the star the Magi followed was in fact a comet is a compelling one. A truly dramatic comet such as Ikea-Seki in 1965 can present a long, sweeping tail after its perihelion passage near the Sun and can even be visible in broad daylight. One can imagine the Magi breaking camp at dawn as a spectacular comet rises in the east before sunrise. While there are many comets whose periods are known, a long-period comet such as Hale-Bopp in 1997 can appear in the inner solar system without warning. Halley’s comet is the best known of all periodic comets, but it was visible from Earth in 12 BC — several years before Jesus’ birth. One problem with the comet hypothesis is that they were usually seen as harbingers of doom. Shakespeare himself once wrote that, “The heavens themselves blaze forth for the death of princes.” Still, it’s always possible that a bright comet could make itself known today, and its previous passage could be traced back to events recorded in biblical times.


1. An Unexplainable Phenomenon

Perhaps there is no scientific explanation for the Star of Bethlehem.

Photo credit: Anneka/Shutterstock.com

Perhaps, as many scholars have suggested, the source of the Star of Bethlehem is meant to remain a mystery. Certainly, if the idea that a star went before them until it stood like a beacon over Bethlehem is taken literally, then no astronomical phenomena would suffice. Any of the above proposals would seem fixed in the vault of the sky and rise and set along with the Sun, Moon and stars. Then there is the problem of the Magi hailing from the east of Bethlehem and relating to Herod that they had seen “… the star, which they saw in the east, went before them, until it came and stood over where the young child was…” this would make it seem like they should have been heading away from Bethlehem. (Maybe they were encamped to the west of the city?) Perhaps the true story will never be known and the Star of Bethlehem as told in the Book of Matthew will remain either an embellishment surrounding the Christmas story or a true miracle that defies scientific explanation. Whatever the source, it’s an interesting thought exercise to wonder just what those three kings of Orient might have seen shining in the eastern skies, long ago.


Written by

David Dickinson is a backyard astronomer, science educator and retired military veteran. He lives in Hudson, Fla., with his wife, Myscha, and their dog, Maggie. He blogs about astronomy, science and science fiction at www.astroguyz.com.