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The Christmas Star

One the questions often posed to and by astronomers this time of year is “What was the Star of Bethlehem?” Was the Star of Bethlehem a real astronomical event? Was it a myth created by the early church? Or could it have been something else?

The Star of Bethlehem is a star in Christian tradition that revealed the birth of Jesus to the Magi or wise men and led them to Bethlehem. According to the Gospel of Matthew[1], the only place in the New Testament mentioning the Star, the Magi were men from the east who were inspired by the appearance of the Star to travel to Jerusalem to search for the “King of the Jews”.[2] In Jerusalem the Magi met King Herod, who informed them that the child that they were searching for was in Bethlehem. The Magi traveled to Bethlehem, found Jesus and his parents, paid homage to him, presented him with gifts and then returned to the lands from which they came.[3]

Because the magi told Herod that they saw the star “at its rising”,[4] it is easy to assume that the Star of Bethlehem is an astronomical object. If the Star of Bethlehem was an astronomical event, it must have been a comet, a nova, a supernova, or a planetary conjunction. To ascertain what astronomical event corresponds to the Star of Bethlehem was, we first need to attempt to determine the date of Jesus’ birth.

Determining the Date of Jesus’ Birth

While there is no historical accounting of the birth of Jesus, we know, from biblical references, that Jesus was born while Herod was King.[5] Herod reigned between 37 and 4 B.C.E. We also know from biblical accounts that the wise men came to pay respects to the child Jesus,not the newborn Jesus. This conclusion was reached based upon King Herod’s orders to kill every child in and around Bethlehem who were two years old or younger. [6]

Jesus was “about” thirty when he began his ministry,[7] and the books of Matthew, Mark, Luke, John, and Acts of the Apostles, the Jewish author Josephus and the Roman author Tacitus all state that Jesus was killed during the rule of Pontius Pilate, the governor of Judea, C.E. 26 through 36. [8][9][10] Also, John the Baptist and Jesus began their ministries around the same time, that is in the fifteenth year of the reign of Emperor Tiberius (C.E. 14-37), when Pontius Pilate was governor of Judea (C.E. 26-36), Herod Antipas was tetarch of Galilee and Perea (4 B.C.E.-C.E. 39), Herod Philip was tetarch of Batanea, Trachonitis, and Auranitis (4 B.C.E.-C.E. 34), and Caiaphas was high priest (C.E. 18-36). This places the date between C.E. 27 and 29.[11]

So, if Jesus was about thirty in the years C.E. 27 through 29, and was born while Herod was King, and was at least two before Herod’s death in 4 B.C.E., then Jesus was born somewhere between 7 and 5 B.C.E..

We seem to have narrowed down Jesus’ birth year to somewhere between 5 and 7 B.C.E. Since the Magi visited the child Jesus and King Herod ordered the deaths of all children 2 years and younger, the Magi visit occurred between 4 and 5 B.C.E.

Can we determine at what time of the year Jesus was born? Let’s take a look at the Book of Luke again. Luke records that shepherds were watching over their flocks by night[12]. There are only two specific times in a year when this was done, namely when lambs were being born in the spring or autumn. At other times of the year they were kept safely in their sheep-folds to protect them from wild animals. So Christmas may be celebrated eight months too late. Without historical documentation it may ultimately be impossible to know the day and month of Jesus’ birth.

These estimates are as close as we can get, without an historically documented event.

Finding an Astronomical Event

The sole unusual event surrounding Jesus’ birth that is mentioned in the Bible is the Star of Bethlehem, so we look to the skies.

What astronomical events occurred in those three years? In 7 B.C.E. there was a triple conjunction of Jupiter and Saturn in Pisces, one in late May, one in late September, and one in early December. A conjunction is when two or more objects appear very close together on the sky. Pisces is associated with the Jewish people in astrology, so when Jupiter and Saturn passed very close to each other three times during the span of several months in 7 B.C.E. it was a notable event. Adding to the significance of this conjunction is that this triple conjunction in Pisces occurs once every 900 years.

In February, 6 B.C.E., Jupiter, Saturn, and Mars passed within 8° of each other in the constellation Pisces. This near conjunction occurs only once every 800 years[13]. Jupiter was the “star” of royalty and luck. Saturn was the “star” of the Mesopotamian deity who protected Israel. These conjunctions would have been easily predicted by astronomers/astrologers of the time and most likely interpreted as a great king was to be born in Israel.

In March/April of 5 B.C.E. Chinese astronomers recorded a “new” star in the constellation of Capricorn which
was visible for over 70 days[14]. The “new” star could have been a nova or a supernova. A nova is caused by a white dwarf gathering enough material, usually from a nearby companion in a binary system, onto its surface to raise the surface pressure high enough for a thermonuclear explosion. The white dwarf’s increase in brightness may be a factor of 10,000 to over one million. The increase to peak brightness is very rapid, within a few days, while the fading away to invisibility usually takes a few months. A supernova is caused when a star at least 8 times as massive as our Sun reaches the end of its life and suddenly explodes and throws off most of its mass. For a few days a supernova may outshine its host galaxy and will slowly fade away. This “new” star would have been visible in the east, several hours before sunrise.

In May of 5 B.C.E. Jupiter emerged from behind the Sun and passed through a stationary point in September. Jupiter appears stationary for about a week at the beginning and end of a retrograde motion cycle. Could this have been the Christmas Star? Unlikely, the magi were astrologers and would have recognized these events for what they were.

Could the “new” star in March/April of 5 B.C.E. have been a comet? Probably not. The Chinese called comets “broom stars” because of their tails. Although the “new” star could have been a comet with a tail too faint to detect without optical aid, the Chinese astronomers did not report any movement of the “new” star; and as we all know, comets move across the sky[14]. Halley’s comet made an appearance in 12 B.C.E., but that is outside the probable date range for the birth of Christ.

None of these events seems to fit the Star of Bethlehem very well. But if the assumption is made that the Magi visit occurred when Jesus was between 18 and 24 months old. And that this visit was triggered by a celestial event. The conjunctions of 7 B.C.E. are out of the range of probable dates of the Magi visit. As is the conjunction of 6 B.C.E. It is unlikely that the motions of Jupiter in 5 B.C.E. would have caused astrologers to begin a journey to Bethlehem. This leaves the new star of March and April 5 B.C.E. As the “best fit” to be the “Star of Wonder”.

As to other sources of the Star of Bethlehem, I will leave that to others to ponder. The Star is what it is: a symbol of hope to over a billion people.

References

  1. Matthew 2:11
  2. Matthew 2:1-2
  3. Matthew 2:11-12
  4. Matthew 2:2
  5. Matthew 2:7-10
  6. Matthew 2:12-16
  7. Luke 3:23
  8. Joseph ben Matthias (Flavius Josephus) 70, The Jewish War
  9. Joseph ben Matthias (Flavius Josephus) 93, Jewish Antiquities
  10. Tacitus 81, Annals
  11. Luke 3:1-2
  12. Luke 2:8-9
  13. Bulmer-Thomas, Ivor 1992, Quarterly Journal of the Royal Astronomical Society, vol. 33, p. 363.
  14. Kidger, Mark, “Chinese and Babylonian Observations”

The Christmas Star is a post from: San Antonio SkyWatch.
Copyright © 2007-2011 by Scott Logan. All rights reserved.

The Legend of Halloween

To view the flash content, please go to The Legend of Halloween

Halloween

Halloween’s origins date back to the ancient Celtic festival of Samhain (pronounced sow-in). The Celts, who’s history dates back 4,000 years, primarily lived in the area that is now Scotland, Ireland, Wales, Brittany, and Portugal, although their empire stretched from Ireland in the west to Turkey in the east, celebrated their new year on November 1.

This day marked the end of summer and the beginning of the dark, cold winter, a time of year that was often associated with human death. Samhain was also the day when the herders led the cattle and sheep down from their summer hillside pastures to the shelter of stable and byre. The hay that would feed them during the winter must be stored in sturdy thatched ricks, tied down securely against storms. All of the harvest must be gathered in — barley, oats, wheat, turnips, and apples — for come November, the faeries would blast every growing plant with their breath, blighting any nuts and berries remaining on the hedgerows. Peat and wood for winter fires were stacked high by the hearth. It was a joyous time of family reunion, when all members of the household worked together baking, salting meat, and making preserves for the winter feasts to come. The endless horizons of summer gave way to a warm, dim and often smoky room; the symphony of summer sounds was replaced by a counterpoint of voices, young and old, human and animal.

The Celts believed that on the night before the new year, the boundary between the worlds of the living and the dead became blurred. On the night of October 31, they celebrated Samhain, when it was believed that the ghosts of the dead returned to Earth interacting with the living. To commemorate the event, Druids built huge sacred bonfires, where the people gathered to burn crops and animals as sacrifices to the Celtic deities.

During the celebration, the Celts wore costumes, typically consisting of animal heads and skins, and attempted to tell each other’s fortunes. When the celebration was over, they re-lit their hearth fires, which they had extinguished earlier that evening, from the sacred bonfire to help protect them during the coming winter.

By A.D. 43, Romans had conquered the majority of Celtic territory. In the course of the four hundred years that they ruled the Celtic lands, two festivals of Roman origin were combined with the traditional Celtic celebration of Samhain.

The first festival was Feralia, a day in late October when the Romans traditionally commemorated the passing of the dead. The second festival was a day to honor Pomona, the Roman goddess of fruit and trees. The symbol of Pomona is the apple and the incorporation of this celebration into Samhain probably explains the tradition of “bobbing” for apples that is practiced today on Halloween.

By the 800s, the influence of Christianity had spread to the Celtic lands. In the seventh century, Pope Boniface IV designated November 1 as All Saints’ Day, a time to honor saints and martyrs. It is widely believed today that the pope was attempting to replace the Celtic festival of the dead with a related, but church-sanctioned holiday. The celebration was also called All-hallows or All-hallowmas (from Middle English Alholowmesse meaning All Saints’ Day) and the night before it, the night of Samhain, began to be called All-hallows Eve and, eventually, Halloween. Even later, in 1000 A.D., the church would make November 2 All Souls’ Day, also known here as Dia De Los Muertos, a day to honor the dead. It was celebrated similarly to Samhain, with big bonfires, parades, and dressing up in costumes as saints, angels, and devils. Together, the three celebrations, the eve of All Saints’, All Saints’, and All Souls’, were called Hallowmas.

The Legend of Jack-O’-Lantern

The Irish brought Jack-O’-Lantern to America. Jack was a legendary, stingy drunkard. He tricked the Devil into climbing an apple tree for a juicy apple and then quickly cut the sign of the cross into the tree trunk, preventing the Devil from coming down. Jack made the Devil swear that he wouldn’t come after his soul in any way. The Devil promised. However, this did not prevent Jack from dying. When he arrived at the gates of heaven, he was turned away because he was a stingy, mean drunk. Desperate for a resting place, he went to the Devil. The Devil, true to his word, turned him away. “But where can I go?” plead Jack. “Back where you come from,” spoke the Devil. The night was dark and the way was long, and the Devil tossed him a lighted coal from the fire of Hell. Jack, who was eating a turnip at the time, placed the coal inside and used it to light his way. Since that day, he has traveled the world over with his Jack-O’-Lantern in search of a place to rest. Irish children carved out turnips and potatoes to light the night on Halloween. When the Irish came to America in great numbers in the 1840s, they found that a pumpkin made an even better lantern, and so this “American” tradition came to be.

The Great Galaxy in Andromeda

By the end of evening twilight tonight the Great Galaxy in Andromeda, also know as M31, is well placed for observing. With no interfering moonlight, a fine opportunity is awaiting skywatchers in dark locations. Use the Great Square of Pegasus as a starting point. This “sky mark,” now rotated into a diamond shape, sits more than halfway up in the east. Sight across the diamond from the upper left corner star, β Pegasi or Scheat, to the lower left corner star, α Andromedae or Alpheratz, formerly known as δ Pegasi. Continue in that same general direction you will find a 3rd magnitude star called δ Andromedae. Take a slightly more northern course to 2nd magnitude β Andromedae or Mirach, lying about 8° to the northeast of δ Andromedae. Make a 90° turn to the right and move about 3½°. You are now at μ Andromedae, a 4th magnitude star. Making a slight course adjustment to the left and moving about 3° you will come to 5th magnitude ν Andromedae. Now slowly scan the area with a good pair of binoculars. You are looking for a faint oval glow, about 1½° to the southwest, that easily fits in the binocular field of view.

Laptop Screen Filters

Many astronomers use laptop computers in the field. Unfortunately, using a “night mode” theme or skin is not enough to reduce the brightness of the screen to a level that will not damage your eye’s dark adaptation. To do that you will need a piece of red acrylic plastic. Here, in South Central Texas you can find red acrylic at:

Plastic Supply of San Antonio
102 Josepine St
210.222.8091

The most recommended thickness is 060 (1/16″), which is item #2423.

The Legend of Halloween is a post from: San Antonio SkyWatch.
Copyright © 2007-2011 by Scott Logan. All rights reserved.

October Sky Challenges

Astronomers and Star Gazers need a challenge when observing.  Novices can be easily overwhelmed by long lists of challenging objects.  Expert observers can be so focused on their projects, they easily can ignore the challenge provided by observing with different instruments.

By presenting three objects in each of several different groups, the hope is to provide all observers, no matter what their experience level, no matter what type of instruments they have access to, challenging objects to observe.  There is even a group for the one instrument we are all born with, the naked-eye.  Astrophotographers and astroimagers are not ignored here, either.

No matter what your experience, no matter what you use to observe, get outside and “Keep looking up!”[1]

This month Urban Skies Observing Challenges have been added.

October’s Sky Challenges

Naked-Eye Challenges

  • Galilean Moons of Jupiter
  • Comet 103P Hartley 2
  • Asteroid 82158 2001 FP185

Binocular Challenges

  • NGC 7788, an open cluster of about 20 stars in Cassiopeia
  • ζ Cepheus, a binary star
  • Melotte 15, an open cluster of about 40 stars in Cassiopeia

Small Telescope Challenges

    For 2″ to 6″ telescopes:

  • NGC 663, an open cluster of about 80 stars in Cassiopeia
  • ι Triangulum, a binary star
  • M77, a class (R)SA(rs)b spiral galaxy in Cetus

Medium Telescope Challenges

    For 8″ to 14″ telescopes:

  • NGC 45, a barred spiral galaxy of class SAB(s)dm in Cetus
  • NGC 821, an elliptical galaxy in Aries
  • NGC 972, a spiral galaxy in Aries

Large Telescope Challenges

    For 16″ and larger telescopes:

  • NGC 185. a dwarf spheroidal galaxy (type dSph/dE3) in Cassiopeia.   NGC 185 is a satellite of M31
  • M33, the Triangulum Galaxy, a type SA(s)cd spiral galaxy
  • NGC 1024, a spiral galaxy in Aries

Urban Observing Challenges

  • Comet 103P Hartley 2
  • Kruger 60, an interesting binary star system in Cepheus. With a short period of only 44.7 years, you can easily see Kruger 60’s PA change about 8 degrees per year.   Also it is only 13 light years away, making Kruger 60 one of Earth’s nearest neighbors.  Both components are low-mass red dwarfs, Kruger 60 B is one of the lowest mass stars known at 0.18 M⨀.  Finally, Kruger 60 B is also a flare star, irregularly doubling in brightness for periods lasting about 5 to 10 minutes. When it flares, it can match or exceed Kruger 60 A in brightness
  • Neptune

Urban Skies Observing Challenges

  • Novice: Any Solar System Object
  • Intermediate: M31 – The Great Andromeda Galaxy
  • Expert: NGC 7293 – The Helix Nebula

Astrophotography/Imaging Challenges

  • Novice: Any Solar System Object
  • Intermediate: M31 – The Great Andromeda Galaxy
  • Expert: NGC 7293 – The Helix Nebula

References

  1. Jack Horkheimer, Star Gazer, 1976

October Sky Challenges is a post from: San Antonio SkyWatch.
Copyright © 2007-2011 by Scott Logan. All rights reserved.