This image, from the Chandra orbital telescope, shows one of the most spectacular objects in our galaxy, the Crab Nebula. The nebula was formed about 8,000 years ago, when a huge star having 10 times the mass of our sun exploded into a supernova. The remnants of the exploded star then collapsed into a pulsar: a very dense, pulsating astral body, whose radioactive output now illuminates stellar dust clouds in a region some 10 light-years across, creating this scene.

Because the Crab Nebula is about 7,000 light-years from Earth, the flash of the supernova detonation traveled toward our world for thousands of years before being observed in 1054. Chinese astronomers wrote extended commentaries on the sudden, brief appearance of an exceptionally bright star. Around the same time, American Indians in Arizona drew cave paintings of an abnormally splendid object in the heavens.

What does this have to do with the star of Bethlehem?

Over the centuries, many have speculated that the celestial beacon described in the gospel of Matthew might have been a comet or an unusual alignment of planets: The 17th-century astronomer Johnanes Kepler theorized that a rare conjunction of constellations produced the illusion of a huge, sudden star. Once the mechanisms of supernovas were understood, they became an obvious candidate for the Bethlehem star. In the past millennia, there have been three supernovas bright enough to dominate the sky: the Crab supernova in 1054, and others in 1572 and 1604. So could a supernova have shown over Bethlehem?

Two similarly named books by scholars explore such possibilities, "The Star of Bethlehem: The Legacy of the Magi" by Michael Molnar, and "The Star of Bethlehem: An Astronomer's View" by Mark Kidger. Kidger presents evidence that there was a supernova visible from Earth in the year 5 B.C.E. (Most historians date Jesus' birth year as 6 B.C.E. or 5 B.C.E.) Molnar goes on to detail the notion that the ancients, who read the heavens for signs and portents, would have been more impressed by astrologically charged events than by pure candlepower. He finds that on April 17 of the year 6 B.C.E., the planet Jupiter, usually the brightest object in the night sky, made extremely unusual motions through Aries (from Earth it would have appeared to reverse its motion, then stop over the Middle East, then reverse again). This would have caused anyone born at that moment to be considered divinely blessed.

Of course, no one can be certain whether there was a special star over Bethlehem or whether this is legend. But perhaps astronomers will someday find in the heavens another structure similar to the Crab Nebula, the collapsed pulsar of a supernova that once generated the glistening light seen by shepherds on a hill above an inn.