Archive

Archive for the ‘Astronomical History’ Category

12/27/2022 – Ephemeris – 2022: We finally saw the black hole at the center of our galaxy

December 27, 2022 Comments off

This is Bob Moler with Ephemeris for Tuesday, December 27th. Today the Sun will be up for 8 hours and 49 minutes, setting at 5:08, and it will rise tomorrow at 8:19. The Moon, 2 days before first quarter, will set at 10:30 this evening.

Besides the James Webb Space Telescope coming online in July, beginning, hopefully, twenty plus years of astronomical discovery, the Event Horizon Telescope Collaboration released an image of the black hole at the center of the Milky Way, 26,000 light years away In the direction of the constellation of Sagittarius. The collaboration, which consists of eight radio telescopes spread out from Hawai’i, to Europe, from Greenland to the South Pole, observed the black hole, dubbed Sagittarius A* (Pronounced Sagittarius A Star) for hours at the same time. The signals were recorded on disc drives, synchronized by atomic clocks, and then sent to a central processing center to create the image. The image was released last May of a fuzzy donut of the black hole and its accretion disk.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.

Addendum

Event Horizon Telescope

Event Horizon Telescope component radio telescopes. Credits: © APEX, IRAM, G. Narayanan, J. McMahon, JCMT/JAC, S. Hostler, D. Harvey, ESO/C. Malin.

Milky Way Black Hole

This is the image released May 12, 2022 by the Event Horizon Telescope Collaboration.

M87 compared to Sagittarius A*

M87* size compared to Sagittarius A*. The size of a black hole is directly related to its mass. M87* has a mass of 6.4 billion times the Sun’s mass. It’s 55 million light years away. The mass of Sagittarius A* is only 4.2 million solar masses, and 26,000 light years away. Image credit: Event Horizon Telescope Collaboration.

Jansky's antenna reconstruction at NRAO, Green Bank, WV

Karl Jansky’s antenna reconstruction at the National Radio Astronomy Observatory, Green Bank, WV. He could rotate the antenna to find the direction of the source. He found that the source rotated with the sky, and the direction was the azimuth of the constellation of Sagittarius the archer. The source was later dubbed Sagittarius A. It is the brightest radio source in the sky. Click on the image to enlarge it. Credit: mine.

When radio astronomy was in its infancy, bright radio sources were labeled with the constellation they were in and a capital letter. Astronomers didn’t know what they really were. Karl Jansky’s discovery of the first celestial radio source in 1933 has been dubbed Sagittarius A, or Sgr A for short. He worked for Bell Labs, and was seeking the source of interference with wireless telephony transmissions. The source was from the general direction of the center of the galaxy, our Milky Way Galaxy, in the direction of the constellation of Sagittarius the archer.

12/23/2022 – Ephemeris – Hunting for the Star of Bethlehem: Venus and Jupiter appear to merge… twice!

December 23, 2022 Comments off

This is Ephemeris for Friday, December 23rd. Today the Sun will be up for 8 hours and 48 minutes, setting at 5:06, and it will rise tomorrow at 8:18. The Moon is new today, and won’t be visible.

My favorite astronomical solution to the puzzle of the Star of Bethlehem are two conjunctions of Jupiter and Venus that occurred against the stars of the constellation of Leo the lion 10 months apart on August 12th 3 BCE and June 16th 2 BCE. Leo at that time was associated with Jacob’s son Judah and the land of Judea. The first conjunction occurred in morning twilight. The second in the evening. The first conjunction was close, though someone with excellent eyesight might pick them apart, but the second, would be impossible to separate without a telescope, which wouldn’t be invented for another 16 centuries. And Jesus would have been born in the spring during lambing season when shepherds would have been out all night with their flocks, protecting them. The eclipse that Herod died after would have been on January 10th, 1 BCE, which occurred three months before Passover, enough time for all the palace intrigue* to happen between the lunar eclipse and Passover.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.

* See yesterday’s post for more information here.

Addendum

Babylonian depiction of Leo.

The Babylonian concept of the constellation Leo. They called it Urgulu, meaning lion. It represented their god Latarak. The star they called Sharru, meaning King we know as Regulus, which is the diminutive of king.

August 12, 3 BC conjunction

Here is an animation created using Stellarium of Jupiter and Venus, the brighter of the two seeming to coalesce on August 12, 3 BC in the early morning twilight. That ghost object that flashed on for one date was the Moon. Created using Stellarium and GIMP.

The second appearance of the "Star"

On June 16th 2 BC, this time in the evening, Venus and Jupiter seem to coalesce as one, at least to the naked eye. Created using Stellarium and GIMP.

Telescopic Jupiter and Venus 6/17/-1 BC.

Venus appeared among Jupiter’s moons on June 16, 2 BC. Of course, no one had a telescope back then. The telescope wouldn’t be invented for another 16 centuries. Stellarium cannot create the real brightness difference between Jupiter and Venus. Venus would be simply dazzling compared to Jupiter, being 12 times brighter. Venus, being an inner planet, shows phases like the Moon. At this time, Venus would have been near its greatest eastern elongation or separation from the Sun, so it would appear as a tiny first quarter moon. Galileo discovered that Venus had phases and orbited the Sun, in the early 17th century. Created using Stellarium.

Merry Christmas!

12/22/2022 – Ephemeris – Hunting for the Star of Bethlehem: When did Herod the Great Die – Part 2

December 22, 2022 1 comment

This is Ephemeris for Thursday, December 22nd. Today the Sun will be up for 8 hours and 48 minutes, setting at 5:05, and it will rise tomorrow at 8:17. The Moon, 1 day before new, will rise at 8:56 tomorrow morning.

According to the Gospel of Matthew, Jesus was born in the last years of the reign of Herod the Great, and the Jewish historian Josephus puts Herod’s death shortly after an eclipse of the Moon. There may have been an error in the Josephus history that has been propagated since the middle of the 16th century, that when corrected shifts the eclipse in question forward three years to 1 BCE. The conjunctions of Jupiter and Saturn of 7 BCE would be four years too early. Under this scenario, Jesus would have been born in the spring of 2 BCE, the time of year when shepherds would indeed be out at night with their flocks, because this was lambing season. What the Magi would have seen was, on two occasions, the planets Venus and Jupiter appear to merge into a single star.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.

Addendum

Timeline of events surrounding the Nativity

This is a timeline I developed of the events surrounding the Birth of Jesus. On the top line in yellow are the two eclipses of the Moon that occurred in the time period we’re interested in: 4 BCE and 1 BCE. One of then was the eclipse Josephus mentions that occurred shortly before the death of Herod the Great, who was alive to greet the Magi, who came to Jerusalem seeking the newborn King of the Jews. The second line highlights 3 and 2 BCE that the early Christian writers Irenaeus, Tertullian and Clement of Alexandria based Jesus’ birth year to Roman events which can be pegged to the Roman Calendar which has a direct relationship to our own calendar. The next line contains hits based on the Crucifixion of Jesus at age 33, where the Last Supper was a Seder on the first day of Passover. The next line with C and P are two censuses of Augustus in our time period. The next to the last line shows the relation of the triple conjunction in 7 BCE with Jesus’ birth and Herod’s death. The bottom line related the two Venus-Jupiter conjunctions with Jesus’ birth and Herod’s death.

Where the lunar eclipse of March 13 of 4 BCE was a slight partial eclipse. The lunar eclipse of January 10 of 1 BCE was total, which occurred three or four months before Passover. Herod’s death and the chaos that ensued, according to Josephus, before Passover also means the March 13, 4 BCE eclipse, occurring 1 month before Passover does not provide the length of time for all these events to transpire:

  • Josephus mentions an eclipse of the moon.
  • Herod went beyond the river Jordan to the warm baths at Callirrhoe by the Dead Sea.
  • He knew he was near death as the treatments failed, so he returned to Jericho.
  • Before he did, he had his soldiers paid a bonus.
  • He ordered all the principal men of the Jews to meet with him under penalty of death. Those who did come, were imprisoned at the Hippodrome to be killed upon his death.
  • Herod then attempted suicide.
  • Herod’s son Antipater attempted to take the throne, and was executed.
  • Five days later, Herod died.
  • Herod had bequeathed the kingdom to another son, Archlaus, who then organized the funeral for Herod.
  • The funeral procession could have taken up to 25 days.
  • Then there were 7 days of mourning after that.
  • Archlaus sent his generals to Caesar on his behalf to have him declared King.
  • The people were beginning to demand lighter taxes and the release of those whom Herod had imprisoned.
  • At that point, Josephus mentioned that Passover was approaching.
  • Finally, it was Passover.

Obviously, all these events could not be squeezed into one 29 to 30 lunar month in 4 BCE. Defenders of the 4 BCE death of Herod would say that the Passover mentioned was the next year’s Passover, giving 12 or 13 months for the events to occur. In that case, why mention Passover at all?

Missing from the timeline above is Luke’s mention of Quirinius being Governor of Syria. However, there is a problem. Luke states the at the time of Jesus’ birth that Quirinius was Governor of Syria. The problem is that he wasn’t Governor of Syria until 6 and 7 CE, at least 8 years after the events of the Nativity. And the question of who was Governor of Syria wouldn’t have mattered until 6 CE, when Judea actually became part of the Province of Syria. In the period we’re looking at, Quintilius Varus was Syria’s governor. Could the two names be switched due to a copyist error? Anyway, this was before Judea became part of Syria, so it wouldn’t have mattered who was governor of Syria when Jesus was born. Luke’s account is not much help in dating the year of Jesus’ birth.

Tomorrow, I’ll finish up with the two conjunctions of Jupiter and Venus against the stars of Leo, which was the celestial sign of Judah and the land of Judea.

12/20/2022 – Ephemeris – Hunting for the Star of Bethlehem: When did Herod the Great Die – Part 1

December 20, 2022 Comments off

This is Ephemeris for Tuesday, December 20th. Today the Sun will be up for 8 hours and 48 minutes, setting at 5:04, and it will rise tomorrow at 8:16. The Moon, 3 days before new, will rise at 6:20 tomorrow morning.

In looking for the year Jesus was born and the appearance of the Star of Bethlehem, we look to the latter years of Herod the Great’s reign. Jewish historian Josephus recounts that Herod died shortly after an eclipse of the Moon occurred. The date of that eclipse, according to many historians, was March 13th, of 4 BCE and before Passover, a month later. The Greek text of Matthew states that Herod’s visitors, looking for the newborn King of the Jews, were Magi. Magi were priest-astrologers of the Zoroastrian Religion of Persia. That being the case, the Star could have been the triple conjunction of Jupiter and Saturn against the constellation of Pisces, when three times Jupiter passed Saturn between the end of May and early December of 7 BCE.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.

Addendum

Triple conjunction

The Jupiter-Saturn triple conjunction of 7 BC. Click on the image to enlarge and animate. This animation is at 5-day intervals. The conjunctions took place against the stars of Pisces the fish, a constellation thought, in those days, to be associated with the Jews. The Moon will be popping in and out of the view. It ends in February of 6 BC, when Mars and the Moon enters the picture. Click on the image to enlarge it. Created using Cartes du Ciel and GIMP.

Above is an animation of the triple conjunction of Jupiter and Saturn of 7 BCE in 5 day steps. The body popping in and frame is the Moon. The first conjunction was on May 29th. Both planets stopped their eastward motion around July 6th. Astrologically, they became stationary and began their westward or retrograde motion. The second conjunction was on October 11th. Both planets stopped their westward or retrograde motion on November 1st. Again they were stationary to resume their normal eastward motion. The third and last conjunction was on December 8th. Two months later, on February 21st, of 6 BCE, Mars joined the group as they all move off to the western sky in the evening. Using this triple conjunction as the Star of Bethlehem, Jesus would have been born in the late autumn of 7 BCE or early winter of 6 BCE.

Lunar Eclipse, March 13, 4 BCE

This lunar eclipse candidate for the eclipse that heralded the death of Herod the Great, and the favorite, since the time of Johannes Kepler, is the lunar eclipse of March 13, 4 BCE. It was a partial eclipse, only visible in the predawn hours. This eclipse occurred one lunar month before Passover.
Too little time for all the events Josephus describes. A better lunar eclipse occurred a bit less than three years later. Those defending the 4 BCE eclipse sometimes suggest that the Passover mentioned by Josephus was the next year’s Passover of 3 BCE. If it was the next year’s Passover, why mention Passover at all?

Tomorrow I’ll take a break to look to the naked eye planets, and to the winter solstice. Winter begins tomorrow! Thursday I’ll look to a better lunar eclipse and begin to explore another Bethlehem Star candidate.

12/19/2022 – Ephemeris – Hunting for the Star of Bethlehem: What it wasn’t

December 19, 2022 Comments off

This is Ephemeris for Monday, December 19th. Today the Sun will be up for 8 hours and 48 minutes, setting at 5:04, and it will rise tomorrow at 8:16. The Moon, 3 days past last quarter, will rise at 4:59 tomorrow morning.

In these last days before Christmas, I’d like to explore what in the sky could have been the Star of Bethlehem from an astronomical point of view. If it had to do with the arrangement of planets, tracing back two thousand years would be simple. If it was some sudden appearance of an actual star or comet, we would have to rely on contemporary accounts. Those would have to come from the Chinese and Koreans. The state of astronomy around the Mediterranean and the Middle East was pretty stagnant due to the fact that they thought that the heavens were perfect and changeless, so things like comets and novae or “New Stars” meant change, so were not really part of the heavens. So we must look for something more mundane.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT –5 hours). They may be different for your location.

Addendum

Probably the first person to kick off the search for the Star of Bethlehem was Johannes Kepler. (These are slides from this year’s Searching for the Star of Bethlehem presentation I gave to the Grand Traverse Astronomical Society. The captions are from the text of the presentation)

Johannes Kepler

The search for the Star really started with Johannes Kepler, who lived from 1571 to 1630. He was an astronomer, although he cast horoscopes for the odd prince or duke, which is how he made a living. His mother was even charged for being a witch, but nothing came of it. And after much trial and error discovered his Three Laws of Planetary Motion. His story is a fascinating one.

Kepler's Nova on a star chart of the time

Kepler also discovered a supernova, the last one seen in the Milky Way. This is an old star chart that records Kepler’s Star,
a supernova, or super bright new star, he discovered on October 9, 1604. I colored it yellow and have an arrow pointed to it, in Ophiuchus’ right ankle.

Kepler's Nova as recreated in Stellarium

Here is a Stellarium recreation of the sky the night of his discovery. It’s the southwestern sky near the end of evening twilight, October 9, 1604, the night Kepler discovered the supernova that bears his name. It got him to thinking, could a similar grouping of a nova and planets be the Star of Bethlehem?
He knew of no nova being reported back then, though no one in the western world probably would have. That would be a change in the officially changeless heavens, so it couldn’t possibly have been a real heavenly object. And being the mathematical genius he was, (he did discover the Three Laws of Planetary Motion), found a very interesting conjunction of Jupiter and Saturn, with Mars piling on later, that occurred in 7 BCE. (Click on the image to enlarge it.)

11/04/2022 – Ephemeris – The GTAS meeting topic tonight is the history of the constellations

November 4, 2022 Comments off

This is Ephemeris for Friday, November 4th. The Sun will rise at 8:24. It’ll be up for 10 hours and 2 minutes, setting at 6:27. The Moon, 3 days past first quarter, will set at 5:06 tomorrow morning.

Tonight at 8 pm, the Grand Traverse Astronomical Society (GTAS) will have their monthly meeting at Northwestern Michigan College’s Rogers Observatory. The meeting will also be available via Zoom. The program will be presented by Becky Shaw. Her presentation will be The History of the Constellations. From time immemorial, people have looked at the night sky and tried to give meaning to the random scattering of stars on the dome of the sky. The official constellations of the International Astronomical Union in most cases date back to the Babylonians, and Greeks. If it’s clear, there will be a star party following the meeting. The observatory is located south of Traverse City off Birmley Road, between Garfield and Keystone roads. A Zoom link will be available at gtastro.org before the meeting. All are welcome.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). They may be different for your location.

Addendum

Summer Constellations showing stars, lines, boundaries, and figures in succession. Click on the image to enlarge it and be able to read the labels. This image shows the stars and planets three years ago in 2019, when Jupiter and Saturn were seen against the summer constellations. Slow poke Saturn has moved into eastern Capricornus. Jupiter is just off the left of the image in Pisces. The head of one of the fish is seen there. Created using Stellarium and GIMP.

Autumn Star Story Constellations

The constellations of the great star story of autumn. Looking southeast on October 31 at 10 p.m. Not all the constellations in this area are shown. Created using Stellarium.

07/04/2022 – Ephemeris – Space firsts, or attempts, on our nation’s birthday

July 4, 2022 Comments off

This is Ephemeris for Independence Day, Monday, July 4th. Today the Sun will be up for 15 hours and 28 minutes, setting at 9:31, and it will rise tomorrow at 6:03. The Moon, 2 days before first quarter, will set at 12:53 tomorrow morning.

To celebrate our nation’s 200th birthday, NASA attempted to land the Viking 1 lander on the planet Mars on July 4th, 1976. The Viking was a combination orbiter and lander and had a twin spacecraft arriving almost two months later. Viking 1 entered orbit on June 19th and began to survey the prime landing area, that radar from the Earth suggested would be smooth, to land on the day of the Bicentennial. However, images from orbit showed too many obstructions, so another area was surveyed. The mission planners from JPL found a spot and sent the Viking lander down to land on Mars on another historic date, July 20, 1976, the 7th anniversary of the Apollo 11 landing on the Moon.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EDT, UT – 4 hours). They may be different for your location.

Addendum

Model of the Viking lander

Model of the Viking lander. Credit NASA/JPL.

First Mars image from Viking 1

The first Mars image from the Viking 1 lander, taken moments after touchdown. The Viking landers used rockets to land, after a parachute descent, because the parachutes would not slow the lander enough in the thin Martian atmosphere. The reason to photograph the landing pad was to see how far it would sink into the surface. Credit NASA/JPL.

NASA did finally make a historic landing on July 4th,

the Mars Pathfinder mission, with the first rover to operate on Mars, the Sojourner rover, landed on July 4, 1997. It was a microwave sized rover. The mission on the surface lasted 85 days.

Pathfinder_collage

Pathfinder collage, Left to right, the collapsed Sojourner rover attached to one of the lander’s tetrahedron petals; 24 inflated airbags, attached 6 to a side of the Pathfinder tetrahedron; launch of the Delta II rocket carrying Pathfinder to Mars. Credit NASA/JPL.

Sojourner rover investigates Yogi

Sojourner rover investigates a rock named Yogi with its Alpha Particle X-ray Spectrometer to determine its composition. Credit NASA/JPL.

Pathfinder Lander from Sojourner

The Pathfinder Lander/Base Station and its deflated airbags from Sojourner. All communications from Sojourner to Earth is relayed through the Base Station. Credit NASA/JPL.

03/08/2022 – Ephemeris – International Women’s Day

March 8, 2022 Comments off

This is Ephemeris for International Women’s Day, Tuesday, March 8th. Today the Sun will be up for 11 hours and 32 minutes, setting at 6:39, and it will rise tomorrow at 7:06. The Moon, 2 days before first quarter, will set at 1:25 tomorrow morning.

The planet Venus is the only major planet named after a goddess. Satellites of the planets are named after both male and female deities. When asteroids were discovered between Mars and Jupiter they began to receive female deity names, however errant asteroids that that came close to the Earth’s orbit received male names. Venus, named after the Roman goddess of love, by convention, has female names for its land forms. But before that convention was adopted the first bright radar feature found on Venus, in 1967, was Maxwell Montes, named after James Clerk Maxwell whose work in the 19th century predicted radio waves. It is by reflected radio waves (radar) by which that feature had been found using the Arecibo radio telescope.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

Venus Map

Radar map of Venus produced by the radar altimeter of the Pioneer Venus Orbiter, 1978-1992. Note Maxwell Montes at the top, part of Ishtar Terra, a continent-like land mass. Another large land mass is Aphrodite Terra in the center right. Click on the image to enlarge it.  Credit: NASA.

02/28/2022 – Ephemeris – Ancient Egypt’s most important star

February 28, 2022 Comments off

This is Ephemeris for Monday, February 28th. Today the Sun will be up for 11 hours and 7 minutes, setting at 6:29, and it will rise tomorrow at 7:20. The Moon, 2 days before new, will rise at 7:17 tomorrow morning.

The Ancient Egyptian agricultural year began with the flooding of the Nile, which was announced by the heliacal rising of the brightest nighttime star, Sirius. A heliacal rising is the first appearance of a star in the morning twilight after disappearing in evening twilight some months before. The Greeks called the star Sothis, while the ancient Egyptians called the star Sopdet. The heliacal rising would occur on July 20th had our calendar been in use back then. The relationship between the summer solstice and the heliacal rising of Sothis, 29 days later, stayed the same for nearly three millennia, from at least 2900 BCE to 12 CE, despite precession* of the Earth’s axis moving the Sun from the middle of the constellation Leo at the summer solstice to the western edge of Cancer one and a half constellations west. Sopdet was personified by a goddess, who was the consort to Sah, who is what they called Orion.

———-

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

* Precession of the equinoxes. The slow, 26,000 year wobble of the Earth’s axis which causes the Earth, most of the time, to not have a pole star. We’re lucky to live at a time to have a bright star within a degree of the north celestial pole. That star is, of course, Polaris. Precession also changes the point in the sky, along the ecliptic and zodiac, where the Sun appears on the first day of spring, or any season. These points move westward along the ecliptic (the plane of the earth’s orbit of the Sun) one degree every 72 years.

Addendum

The Egyptian used the heliacal rising of Sirius as a signal that the flooding of the Nile was imminent, starting their agricultural year. The Greeks called the star Sothis, while the Egyptians themselves called it Sopdet, a goddess, and consort of the god Sah, our Orion.
Part of my presentation, December 2021 of Ancient Astronomy of the Egyptians and Babylonians.

02/21/2022 – Ephemeris – The time President Abraham Lincoln visited the US Naval Observatory

February 21, 2022 Comments off

This is Ephemeris for President’s Day, Monday, February 21st. Today the Sun will be up for 10 hours and 46 minutes, setting at 6:19, and it will rise tomorrow at 7:32. The Moon, 2 days before last quarter, will rise at 12:09 tomorrow morning.

In August 1863, during the height of the Civil War, President Abraham Lincoln and his secretary John Hay rode out to the Naval Observatory, where it was back then in Foggy Bottom. The astronomer there, Asaph Hall, showed them the Moon and the star Arcturus through the observatory’s telescope. A couple of nights later Lincoln came out alone to ask the astronomer some questions about what he saw, in including why the Moon was upside down in the observatory telescope while the telescope he used gave a right side up image.* Fourteen years later, Asaph Hall, still at the Naval Observatory, discovered the two satellites of Mars through the observatory’s then larger telescope.

The astronomical event times given are for the Traverse City/Interlochen area of Michigan (EST, UT – 5 hours). They may be different for your location.

Addendum

9.6 inch refractor

The 9.6 inch telescope through which Lincoln viewed the Moon and Arcturus on the night of August 22, 1863. From the Astronomy.com website.

Old Naval Observatory

The old Naval Observatory. From the Astronomy.com website.

* Most telescopes naturally create an upside down image. The spyglass type telescope President Lincoln was probably familiar with was a Galilean telescope that didn’t form an image within it. Telescopes like binoculars use prisms to erect the image. Astronomers don’t care if the image is upside down. Whatever is used to turn the image right side up reduces the amount of light that makes it through the telescope. For astronomers, the name of the game is to capture more light and increase the ability to see fine detail, which are both functions of the primary’s diameter. That’s why modern telescopes are measured by the diameter of their primary mirrors or lenses.