The Star of Bethlehem and other heavenly wonders

As an undergraduate at the University of Michigan, I enjoyed giving an annual Christmas program about the Star of Bethlehem in the planetarium on the top floor of the natural history museum. Visitors oohed and aahed as planets and stars swirled overhead, recreating the night skies over the ancient Middle East.

Since the 1940s, such shows have become something of a tradition for planetariums across the country. While fun, they may leave an unwarranted residue of certainty about this important celestial event.

The second chapter of the Gospel of Mathew quotes wise men as saying, “Where is he that is born king of the Jews? For we have seen his star in the east, and are come to worship him …” The 47 scholars who worked on the King James Version of the Holy Bible translated the Greek word “aster” as “star,” but subsequent experts say “aster” could have referred to any bright object in the sky.

For our ancestors, natural lights in the sky didn’t have to compete with glowing golden arches, colorful iPad displays, and episodes of “Dancing With the Stars.” Our long-ago relatives followed the path of the sun and noted the phases of the moon. They connected star dots to form constellations and developed the mythologies of astrology to explain how stars and their movements impacted human lives. They noted “new stars” or novae that bloomed for a while and then faded from sight. They tracked the special moving “stars” we now know to be planets. They worried about “shooting stars” (meteors) and feared “tailed stars” (comets) for what evils they might portend. Wise men paid devout attention to the amazing manifestations overhead.

Determining the identity of the Star of Bethlehem requires not only knowledge about celestial events, cyclical and transitory, but also about historical figures and events near the time of Jesus’ birth. Then, this information must be correlated with Roman and Gregorian calendars and the wobbles of our planet’s axis that slowly change our view of the sky. Most scholars, religious and secular, place the birth of Christ shortly before the death of Herod the Great — sometime between 4 B.C. and 6 B.C.

Johannes Kepler (1571-1630) lived during the transition in thinking referred to as the scientific revolution. Best known for his mathematical and astronomical observations that led to the formulation of the laws of planetary motion, he also practiced the non-scientific art of astrology. That astrological expertise provided insights into what the Magi of Jesus’ time would have considered important when looking at events in the night sky.

Kepler was able to successfully describe the laws of planetary motion because the work of Copernicus (1473-1543) and his contemporary, Galileo (1564-1642), convinced him that the sun and not the Earth was the center of our solar system. This epiphany explained with great elegance observed planetary behavior, including retrograde motion, when a planet briefly reverses its straight-line path across the sky. Mars, for example, seems to do a small loop in the sky when the faster Earth, which is closer to the sun, zips past the red planet on its inside lane.

Sometimes, the planets appear to meet in the sky when they pass each other at the same celestial longitude. These apparent meetings are called conjunctions. With the help of Kepler’s laws, astronomers can predict future conjunctions and reconstruct ancient ones with great accuracy. Rarely, when an inner planet overtakes a more distant planet as they orbit the sun while at the same celestial longitude, they may appear to “meet” three times (a triple conjunction). The planets meet once and pass each other, then the more distant planet backs up — retrograde motion — and they meet again, and finally they “collide” one more time as the more distant planet resumes its forward motion.

Kepler determined that Jupiter and Saturn had a rare triple conjunction in 7 B.C. followed by an unusual grouping of Jupiter, Saturn and Mars the following year (6 B.C.). Not only that, these events happened within certain constellations of the zodiac that had astrological significance. A similar triple conjunction followed by a massing of the planets had occurred in 1603 and 1604, followed by the appearance of a nova, or new star.

While we know today that novae, or stellar explosions, are random events, Kepler proposed that God had created a similar nova after the massing of the planets in 6 B.C. to herald the birth of Christ. Other scholars feel that just the massing of the planets themselves after such a triple conjunction might have been the Magi’s “star.”

All the speculation hinges on whether passages in the New Testament referring to a “star in the east” represents a historically accurate observation. In truth, science can speculate about what the Star of Bethlehem might have been, but it remains speculation. In fact, one astronomer, Von Del Chamberlain — now retired from the Hansen Planetarium in Salt Lake City — who spent much of his career dealing with this question, laments the fact that “no matter how cautiously we state the information in our programs, many people emerge from them thinking that science can identify what the Star of the Magi actually was.”

Chamberlain chooses to emphasize that “The ‘Star of Wonder,’ whatever it was, was light in the sky, and it has become a marvelous symbol — a symbol of the coming into this world of something pure, an example to emulate that brings with it teachings, something that gives us hope that can inspire living by firm values that give direction and meaning to life.”

As we bask in the manmade lights that glow this time of year in celebration of a history-changing birth, it’s also a good time to reacquaint ourselves with the heavenly show of lights that amazed our ancestors and induced one special trek in search of an inspirational king.

Sidebar: Events in the sky for December 2011
Many local stargazers come together at meetings of the Northern Colorado Astronomical Society (ncastro.org or phone 970-223-7210). December features three events of note:
• Friday, Dec. 1 at 7:15 p.m., check the website for location. The meeting will include show-and-tell, telescope-buying advice, telescope help, and an observatory tour.
• Saturday, Dec. 10, public stargazing at Fossil Creek Reservoir Open Space parking area, 5 to 7:30 a.m.; a chance to observe a lunar eclipse as the full moon moves into the shadow of the Earth.
• Friday, Dec. 30, public stargazing at Fossil Creek Reservoir Open Space parking area, 7 p.m.; see the moon, Jupiter, and the winter sky.

The NCAS website also provides information on bright planets in the sky and links to various celestial resources.