Bob Moler's Ephemeris Blog

Ephemeris for Friday, December 2nd.  The Sun will rise at 8:01.  It’ll be up for 9 hours and 1 minute, setting at 5:03.  The Moon, 3 days past new, will set at 8:02 this evening.

This evening at 8 p.m. I will be giving a talk investigating the origin of the Star of Bethlehem.  This will be during the monthly meeting of the Grand Traverse Astronomical Society, at Northwestern Michigan College’s Rogers Observatory located south of Traverse City on Birmley Road.  The talk is a scientific treatment of the subject, rather than a religious one.  We’ll look at what the Gospel writers got right and possibly got wrong.  We’ll look at historical writings and oriental observations of the heavens around that time.  This will be augmented by computer simulations of what might be important celestial events visible around that time.  There is no admission charge.  There will be viewing of the skies afterward if it’s clear.

Times are for the Traverse City/Interlochen area of Michigan. They may be different for your location.

Addendum

The Star of Bethlehem: The case for a 2 BC Nativity date

By Bob Moler

This is a 2016 rewriting of a Stellar Sentinel article from December 1997 as an introduction to my talk this month: In Search of the Star of Bethlehem.

At this month’s meeting of the society I will present again the two thousand 2,000 year old search for the Star of Bethlehem. After studying and dismissing, for a variety of reasons, other phenomena, the quest centers on two rare sets of conjunctions of planets. The first, the favorite of the last 400 years, involves a rare triple conjunction of Jupiter and Saturn over 6 months in 7 BC. It’s 2,000^th anniversary was in 1994.

The triple conjunction fits if King Herod the Great died in 4 BC. Remember according to Matthew the Magi visited Herod in Jerusalem, and were directed to Bethlehem. According to the Jewish Historian Flavius Josephusⁱ, a contemporary of the Gospel writers, Herod died between an eclipse of the Moon and the following Passover. Pretty much the accepted eclipse was a slight partial eclipse on the early morning of March 13, 4 BC. Passover followed the next lunar month later. It turns out that Josephus was a busy boy in his last dayes after the eclipse. A much better eclipse was that of January 10, 1 BC which was total and visible in the evening, and which allowed a span of 3 months for Herod to accomplish the requisite wickedness of his final days. It is this eclipse, and Herod’s death in 1 BC that the events of the 2 BC Nativity date was based.

The second solution involves the planets Jupiter and Venus, which had two nearly stellar conjunctions 10 month’s apart in 3 and 2 BC, 2,000 years ago from 1998 and 1999. If you’re a bit confused about the mathematics of the 2,000 year subtraction, remember there was no year zero, 1 BC was the year prior to AD 1. So mathematically year -1 was 2 BC. Of course the AD/BC calendar numbering wasn’t used back then. Our calendar wasn’t determined for another 500 plus years later. Back then, the Roman calendar (AUC) was in use in the that part of the world.

Adding to the information on the second solution I talked about 20 years ago are more ideas that were graciously sent me by George Petritz. It was an issue of Imprimis, a publication of Hillsdale College. In the December 1996 issue was an article The Star of Bethlehem by Dr. Craig Chesterⁱⁱ, who suggests the 1 BC date for Herod’s death.

It looks like the Star of Bethlehem was not the spectacular apparition we celebrate today in images and song. The importance of the apparition was definitely in the eye of the beholder. And the beholders were the Magi, astrologer priests of the Zoroastrian religion based in Persia. They have worked out the meaning of every planet, position and constellation in the visible heavens, and they were aware of the writings and religions of the nations that surrounded them. So let’s try to see what the Magi might have read into two planetary conjunctions occurring 10 months apart in 3 and 2 BC.

On August 12^th of 3 BC. just before dawn. The two brightest planets Jupiter and Venus merge into a single dazzling star in the dawn twilight. This even occurred below the chin of the constellation of Leo the lion. In the twilight, on the lion’s bright star Regulus was visible.

So here’s the cast of characters. Jupiter then as now was the king of the gods. In Hebrew, it was Sedeq, which meant Righteousness. The Jews worshiped one God, the only God, who created everything, so they didn’t need to see Jupiter as a god.. Venus was the fertility goddess to all except the Jews. To the Babylonians it was Ishtar. However the in Second Kings and Jeremiah the prophets were distresses to find many Jews were indeed worshiping Ishtar. The lion was the king of beasts, and in Genesis 49:9 Jacob associated his son Judah with a young lion. King David was of the tribe of Judah, and so was the Messiah to be. The reference is again repeated in Revelation 5:5, which reveals the power of the association in the early Christian era. Regulus’ name means little king star, an allusion to its location in heart of the king of beasts. The ancients thought that this star ruled the affairs of the heavens.

Beside the conjunctions of Jupiter and Venus, each planet has their own conjunctions of Regulus. Chester also suggests a solution to the problem of the verse in Matthew 2:9, where the star came to a standstill over place where the child was. This seems to be impossible for an astronomical object. Chester’s explanation was that this is when Jupiter reached its stationary points at the beginning and end of its retrograde or westward motion. Well, let’s see the chronology of all these events, as modeled with the free app Cartes du Ciel:

• August 12, 3 BC. – Venus and Jupiter are in their first conjunction, visible low in the eastern twilight before sunrise. Both are moving eastward against the stars.
• August 17, 3 BC. – Venus and Regulus are in conjunction.
• August 24, 3 BC – Venus and Mercury are in conjunction
• September 14, 3 BC. – Jupiter and Regulus are in conjunction.
• November 27, 3 BC. – Jupiter is stationary, and will begin to move in retrograde with respect to the stars, or to the west.
• February 16, 2 BC. – Jupiter and Regulus are in conjunction for the second time, as Jupiter continues the retrograde motion.
• March 29, 2 BC. – Jupiter is stationary, ending retrograde motion, and resuming its prograde or eastward motion.
• May 9, 2 BC. – Jupiter and Regulus are in conjunction for the third time.
• June 10, 2 BC. – Venus and Regulus are in conjunction.
• June 17, 2 BC. – Venus and Jupiter are in conjunction. They appear to merge into a single star low in the west at sunset.

The first conjunction, on August 12^th, 3 BC., apparently set the Magi on their journey. This is the first appearance of the star as recorded in Matthew 2:2. I expect that the knowledge of planetary motions allowed the Magi to predict the second conjunction 10 months later. They may have timed their journey to arrive around that second conjunction.

The Magi expecting a king, went to the capitol city of Judea, Jerusalem. It is a reading from the scriptures that sends them to King David’s birthplace, Bethlehem. As they left Jerusalem the Magi saw the star again. Was this the second conjunction on June 17^th, 2 BC?

The problem of the star standing still over where the child was is still there. If the stationary point of Jupiter is that phenomenon, Jupiter would have reached its stationary or standstill point for the last time a month before the Magi ever got to Jerusalem. The stationary position of Jupiter, will be lost on all but keen watchers of the heavens. Jupiter would still share the stars daily motion through the sky. Another point: Jupiter isn’t the star but the combination of Jupiter and Venus is. I’m afraid the standstill problem is still unsolved.

Recently we have had a repeat of the above celestial events in our skies beginning with a close Venus-Jupiter conjunction on August 18, 2014 with a second conjunction on June 30, 2015. These were close conjunctions, though not as close as the ones in 3 and 2 BC, plus they were also seen against the stars of Leo.

Whether this is the Star, or not, we know it was the light of the star that drew the Magi. Today both Christians and Jews celebrate, in this season of darkness and the longest nights, holidays of light with Christmas and Hanukkah.

i Antiquities of the Jews – Book XVII Chapters 6-8