An important holiday is coming up for many people of the world – Christmas. One of the many symbols of Christmas is the Star of Bethlehem; the star that was said to shine in the East guiding the shepherds, kings, and wise men to the bedside of the newborn Jesus Christ.

“What was that star?” is a question that has fascinated astronomers and non-astronomers for centuries. Setting aside all other questions, there are several possible astronomical events that happened between 20 B.C.E (Before Common Era) and 10 C.E. (Common Era) that could have been described as a “new star” by people of that time period.

Shooting Stars:

Shooting Stars aren’t stars at all, but falling bits of dust and sand burning up in our atmosphere – also known as meteors. They last a couple seconds at most, and are very common. You can see about seven meteors per hour on a normal night. Sometimes they can be very bright, but because they’re so common and short-lived, they probably don’t explain the Star of Bethlehem.

Comets:

European astronomers from around the year 1 didn’t pay much attention to comets, or keep detailed records of their appearances. Chinese astronomers were paying attention, calling them “broom stars,” and they recorded two such stars during the years in question: one in 5 B.C.E, and one in 4 B.C.E. Comets stay in the sky for weeks, are bright enough to be noticed even by everyday people, and look pretty weird if you’ve never seen one before. Plus they stay in almost the same location from day to day. Comets are a good possibility for the Star of Bethlehem, but they don’t look very star-like because they appear very fuzzy.

Comet of Bethlehem? Photo: NASA Edit:Alice

Planets:

Astronomers of the world knew about the planets and were able to track them long before 20 B.C.E. But, there is a possibility that the star of Bethlehem could have been a planet, especially when you start thinking about planetary conjunction which happens when two planets pass close to each other in our sky. When you combine two or three of the brightest planets in the sky (Jupiter, Mars, and Venus), that part of the sky that looks supernaturally bright – or at least catches your eye.
In 7 B.C.E. Jupiter and Saturn passed each other three times (a triple conjunction) within six months. This also happened in 1981 C.E. and will happen again in 2238 C.E. Not much later, in 6 B.C.E. Mars and Jupiter and Saturn all came very close to each other in our sky, a near conjunction. This was all very exciting if you knew what you were looking at (which the Magi did), but probably not that noticeable to everyday people.

Supernovae:

The last astronomical possibility is that the star was either a nova or a supernova. Either one would look like a surprisingly bright star that wasn’t there the night before, and would last for weeks or months. After a while the star would fade from view completely. Once again, European astronomers weren’t that great at recording supernovae, but the Chinese astronomers documented one that was visible in 14 B.C.E. This supernova would have been visible in the east just before sunrise (no star would stay in the east all night; as the earth turns everything in the night sky appears to move from east to west).

Added Section: We Don’t Know

Here’s another explanation for the Star of Bethlehem, courtesy of Steve White, one of our local awesome planetarians. I love it.

Steve says: “Okay, it’s not really an explanation at all, it’s just a category between ‘Comet/Planet/Supernova’ and ‘Miracle.’  There is, after all, a great big gap between ‘stuff we understand’ and ‘acts of God,’ and only a scientist too big for his/her britches would think otherwise.

“Astronomy is full of phenomena that, if not unexplained, used to be unexplained. In fact, we can only begin to explain certain astronomical phenomena that have occurred in the small number of centuries during which we’ve been looking. Any event rarer than that, a once-in-10,000-year event for example, or once-in-100,000-year event, or once-in-a-million year event, etc., would be utterly outside our explanatory capacity.

“Our theories and models may be precise enough to predict it, but not necessarily. If they are, our imaginations may fail us.

“The Star of Bethlehem may have been one of those. This doesn’t help us understand it, and is therefore unsatisfying… but, if we are going to [try to catalog all possibilities], we should consider the possibility of this sort of ‘Fortean’ phenomena as well.”

Miracle:

I feel the need to cover my bases here. I talked about the four different astronomical/astrological possibilities for the Star of Bethlehem, but I haven’t mentioned one very important possibility: a miracle, or something non-astronomical and inexplicable created by God or occurring simply because Jesus was being born. As a scientist, I can’t address this possibility (miracles don’t follow the laws of physics, there’s no test or math I can do to prove one way or the other), but since I don’t have a better explanation, you’re right, I can’t rule it out.

Historical Story:

Oof, ouch, this one is going to hurt a little bit, I’m sorry, but I do want to put it out there. Matthew (and Luke) are the ones who wrote most of the parts about the Star of Bethlehem (Read Matthew:2). My local doctor of medieval literature tells me that Matthew (and Luke) were written after Mark, and Mark was written after 66 C.E.
If Matthew was around during Jesus’s birth, then he’d be about 70, 80, or 90 years old when he wrote his account. Luckily for him, there was a comet (Halley) in 66 C.E., which would be fresh in his memory while he was writing about the Nativity.
Also, if Jesus was to be the Messiah it was prophesied that there would be a star at his birth. Matthew was writing for a Jewish audience, and part of what he was doing was probably trying to convince them that Jesus fulfilled these prophecies. It’s a lot easier for Jesus to fulfill the prophesy of being the Messiah if there’s a star at his birth. Did Matthew use the comet he had just seen as a prop to support his position that Jesus was the Messiah? Did Matthew tell the story as he’d heard it, through the lens of his recent experiences, including the comet as the star? I don’t know.

The Answer:

So what’s the answer? This is science, we don’t presume to know for sure. All of these are possibilities, and until there’s more evidence we have no way of picking one.

Want More?

http://science.nasa.gov/headlines/y2002/24may_duo.htm
http://science.nasa.gov/headlines/y2000/ast16may_1.htm
http://sciastro.net/portia/articles/thestar.htm (Reference from NASA)

Where’d I Get My Info?

Star of Bethlehem Planetarium Show for the Willard Smith Planetarium, December 1997, updated 2008
http://sciastro.net/portia/articles/thestar.htm

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