Sunday, May 9, 2021

Constellation Corvus and Delta Corvi

Last week, I went out on a nominally clear night to see if I could find the Virgo Cluster of galaxies. I could not. But there was a very apparent quadrilateral in the south. So, I targeted that. I found delta Corvi, an interesting binary.

Wikicommons from Sky & Telescope
“Delta Corvi has more than 2.7 times the mass of the Sun, which is causing it to radiate a much higher energy output—roughly 69 times the Sun's luminosity. … Hence it is either a subgiant star around 260 million years old …  or a pre-main sequence star around 3.2 million years old that has not completely condensed and settled on the main sequence.”

Its companion shares its radial velocity and those have not changed measurably since the pair was determined in 1823 by James South and John Herschel. They may be 

The angular separation is given as 24.2 arcseconds. (Wikipedia – Delta Corvi)

The constellation has been called the Crow or the Raven for at least 3,000 years. To the Babylonians, it heralded the autumnal rainy season. The Romans called it Corvus and the Arabs gave it the same name in their language.  

5 May 2021 2300 hrs CDT
 Moreover, delta Corvi was called al-ghuraab, rendered as “Algorab” on European charts, which means crow. Gamma was Gienah or “right wing.” Epsilon Corvi was minqar (Minkar on our modern charts), meaning “wing.” The named attached to Beta, Kraz, has never been traced adequately. 

 The USS Algorab was an Arcturus class attack transport in service from 1939 to 1945. The ship served in the Atlantic, the Caribbean, and the Pacific. For its action in the Pacific, it earned four battle stars.


As a petty officer in the Texas Maritime Regiment, my insignia were crows. I joined the service late in life and was placed in the command group to serve the general staff where I fit in well. However, there were a couple of times when my top sergeant had to counsel me to keep in mind that my crows were not eagles.


Previously on Necessary Facts

Binary Star Project 

Scorpio and the Precession of the Equinox 


Astronomical Symbols on Ancient and Medieval Coins 

Why I Served

Monday, April 19, 2021

To Explain the World by Steven Weinberg

Write about what you know. Write from your experience. Those two mandates are easily given to anyone who wants to write for a living. They apply to fiction and non-fiction. The rules were too easily ignored by Nobel laureate Steven Weinberg 

To Explain the World: The Discovery of Modern Science by Steven Weinberg (HarperCollins, 2015) presents—and I believe, proves—the thesis that science was not invented, but exists independent of the observer. In my words, not his, science is as objective as helium or an elephant: it is what it is for any observer. Although science is a very human pursuit, it would be the same for a practitioner in another galaxy. Dr. Weinberg asserts that modern science had to be discovered. It was not practiced in Ancient Greece, the Islamic Middle East, China, or Medieval Europe. The essence of modern science is the controlled (and therefore “unnatural”) experiment. 

To Explain the World is Dr. Weinberg’s personal review of Western intellectual history. I had several classes in it at university and it remained a pursuit integral to my own lifestyles. So, I had a firm foundation from which to take issue with many of his assertions. However, someone who comes to this book without prior learning will be given some clichés, now abandoned by historians at his level. Some claims are just plain false, though they come well-attributed by second-hand sources. For one thing, Steven Weinberg admits to not reading Greek, though he seems to know Latin well. So, the review of the natural philosophy of the ancient Greeks is based on the usual English translations. 

Weinberg knows science. His Nobel prize attests to that, though his degrees and research seem to be enough. Where he is weak is in history. This is his view, his interpretation. I accept the thesis. I am forced to reject some of the evidence. Also, oddly enough, he is less than perfectly clear on just what science is. Very much like a university textbook, he just assumes that you know the scientific method, though he never defines it and certainly does not investigate how its procedures were integrated into the modern practice we know. (My overview of "The Scientific Method" is here.)


In science, we might accept authority, but we never take anything on faith, and Prof. Weinberg is a teacher. So, this book delivers a special value in the Technical Notes at the end. There, you will find proofs and elaborations of the mathematics, astronomy, and physics supporting the narratives.

Where he goes astray is in the history. The book is replete with small errors of fact. “If Archimedes by his measurement of specific gravity had identified a gilded lead crown as being made of solid gold, he would have become unpopular in Syracuse.” (page 41) The crown was not gilded. If that were the suspicion, just cutting into it would have revealed the lead core. We know hundreds if not thousands of just such false coins from the ancient world. No, the crown was an alloy of silver and gold. The jeweler removed some gold and replaced it with silver. Visibly, the crown looked like pure gold. Only the test of specific gravity betrayed the culprit. It seemed to me to be the salient point, not to be missed or confused by a practicing physicist. Moreover, the book was read through by several others, including historian of astronomy, Owen Gingerich. Someone should have caught it.

Weinberg accepts the common narrative that the ancient Greeks, especially the Athenians, did not value labor and therefore did not perform experiments. Weinberg quotes Shakespeare’s Midsummer Night’s Dream: “Hard-handed men, who work now in Athens, and never yet labor’d with their minds.” (page 34) He could have looked closer to the source. “Now I observe that when we are met together in the assembly, and the matter in hand relates to building, the builders are summoned as advisers; when the question is one of shipbuilding, then the ship-wrights; and the like of other arts which they think capable of being taught and learned. And if some person offers to give them advice who is not supposed by them to have any skill in the art, even though he be good-looking, and rich, and noble, they will not listen to him, but laugh and hoot at him, until either he is clamoured down and retires of himself; or if he persist, he is dragged away or put out by the constables at the command of the prytanes." -- Plato's Dialogues, "Protagoras," translated by Benjamin Jowett.

Weinberg notes that more investigations that we recognize as science were carried out in the Hellenistic era, than in the classical. That is true. Supporting his claim he offers the work of Philo of Byzantium (280-220 BCE), Mechanike Syntaxis, in which an experiment in hydrostatics demonstrates that air is a substance. However, readers or viewers of Carl Sagan’s Cosmos learned that in the classical era Empedocles of Akragas explained the action of a kitchen tool, the water-thief (clepsydra), 200 years earlier. 

Taking common easy claims in lieu of research into ancient history, Weinberg says that the Greeks named the planets Hermes, Aphrodite, Ares, Zeus, and Cronos. (page 77) .They did not. Very many sources, including the works of Otto Neugebauer, correctly identify the ancient Greek names Stilbon, Eosphoros/Hesperos, Pyroeis, Phaetho, and Phainon: Sparkler, Dawn-bringer/Evening, Fiery, Shining, and Blazing. Giving them names analogous to the Roman gods happened much later. Note, also, relevant to ancient astronomy, that the morning star and evening star were only correctly identified much later (by the time of Claudius Ptolemy) and properly identified with the planets Venus and Mercury depending on their relative positions. 

Similar errors mar the history of science in the European Middle Ages. At the start of Chapter 10 Medieval Europe, the seven liberal arts are listed as “grammar, logic, rhetoric, geography, arithmetic, astronomy, and music.” (page 124). Later, geometry is correctly placed among them to replace geography. Even as Weinberg probably made the mistake in his manuscript—an easy enough mistake if you are writing off the top of your head—someone should have caught it. 


This was a library book. A previous patron penciled very neat corrections to the errors in Greek and Latin. Among the half dozen or so, Philo's work was rendered as Mechanice syntaxism.


Weinberg refers to “… Newton’s own commitment to Unitarian Christianity…” (page 245) In point of fact, Unitarianism was anathema to the Anglican Church, and Newton perjured himself to get and keep his job at Cambridge when he swore to the Anglican confession and Trinitarianism. It is not a moot point. Also, though he cites it as a primary source, Weinberg seems to know Newton’s Principia only second hand. He cites Richard S. Westfall’s Never at Rest: A Biography of Isaac Newton (Cambridge 1980) and Chandrasekhar’s Common Reader edition of the Principia. Granted, it is difficult because we do not know geometry at the depth and breadth of Newton's time. We replaced it all with algebra and calculus. (Weinberg makes that point, also.) Even Richard Feynman failed to be able to independently recreate Newton's proof of Kepler's Third Law. (On the blog here.)


At worst, Weinberg’s narratives are as bad as Neil de Grasse Tyson’s. For example, telling of how Galileo rolled marbles off a table to record their path in freefall, Weinberg claims that “… the trajectory is a parabola.” (page 194) It is not. It is an ellipse. We allow college freshmen to assume that the Earth is flat and that gravity vectors point down parallel to each other and perpendicular to the ground. The math is easier and the approximation is close enough. 

The Wonders of Physics: an Introduction to the Physical World 
by Irving Adler  ( Illus. by Cornelius De Witt);
New York: Golden Press [1966].

However, as Weinberg says later: “Halley asked Newton what would be the actual shape of the orbit of a body moving under the influence of a force that decreases with the inverse square of the distance. Newton answered that the orbit would be an ellipse, and promised to send a proof.” (231) Again, this is not exactly true. The path is a conic section—circle, ellipse, parabola, hyperbola, line—depending on the tangential velocity of the object relative to the central force of the ponderable body at the focus. That eccentricity defines the shape of the curve. When you toss a baseball, the path is the same as it would be if you were 13,000 km from an extremely small object with the same mass as the Earth. Throw it faster and faster again and the path becomes a parabola, and then a hyperbola. Impel it extremely fast along any vector except directly at the center of mass and it will zoom off in a straight line, never to return.
Basically, Weinberg’s personal views aside, his editors at HarperCollins failed him. That being so, the thesis stands proved as asserted. However insightful were Democritus or Walter de Merton in teasing out the truths of motion in particular and the physical world in general, their work was not science. Science was a modern discovery. Consequential to that discovery was understanding the distinction between description and explanation. Unfortunately, Weinberg does not say more on that point, even though it is in the title of the book.


It is a whole lot easier to criticize than to create. In Fahrenheit 451, in explaining why he is attracted to reading, the fireman Montag says that inside each book is a man. This book was interesting and informative not because of the traps hidden by the putative histories, but for the opportunity to spend time with Steven Weinberg and to understand his view of his practice of his science.




Copernicus on the Revolution of Heavenly Bodies 

De Magnete by William Gilbert 

Feynman’s Rainbow by Leonard Mlodinow 

Harriman’s Logical Leap Almost Makes It 



Sunday, April 18, 2021

Liza Mundy Breaks the Code and Misses the Message

Write about what you know. Write from your experience. Those two mandates are easily given to anyone who wants to write for a living. They apply to fiction and non-fiction. The rules were too easily ignored by Liza Mundy. Granting that Liza Mundy recorded well what people told her, it is obvious that before she wrote this book, she knew nothing about codes, the military, or World War II. 

 Languages change. I was born in 1949 and in my first grade classroom one of our phonics charts spelled waggon in the old British style, just as Abraham Lincoln wrote shew for show. I mention that because on page 112, Mundy says that Ruth Weston was “olive complected” and I learned “complected” to be regional American dialect and not proper American English. Whatevs.

Code Girls by Liza Mundy 
(Hatchette 2017)
More consequentially, Mundy does not understand why military people salute each other, who salutes whom, and the differences in rules for the customs and courtesies as followed by the Army versus the Navy. She says: “… but Bea Norman felt the Marines guarding each room ‘took pernicious pleasure’ in making the women salute over and over.” (page 169) 

But she also notes later that by the rules, as officers, the WAVES were entitled to salutes from enlisted men (page 191). They would be entitled to the courtesy from all enlisted personnel, regardless of sex, but that aside, the Marines may have been pushing some regulations. One fine point is that by Navy customs, you only salute the first time you see an officer because on board a ship you will see her a hundred times a day. Sailors and Marines would all be waving their arms all the time and in confined spaces. Also, unlike the Army, the Navy does not salute again after coming on deck (or inside a building). That being as it may, the bottom line is easy: If someone salutes you, you return the salute; it is that simple. But clearly, the salient facts are not military customs and courtesies but how many insults and injuries Mundy could find to curry sympathy for the women in the story. 

The irony compounds because in the Index, the women are listed by their married names despite the fact that we worked with them for three, four, or five years when they were single. Among the many people buried in the Index was Genevieve Grotjan who was instrumental in breaking the Japanese Purple cipher. After we follow her work as a cryptanalyst for five years, she is listed as Feinstein, Genevieve Grotjan because she got married on page 344.


The English and Americans broke the Enigma cipher machine in part because an early version of  a cracking machine was delivered to British intelligence by Polish intelligence agents after the German invasion. It was called a “bombe” or sometimes “bomba.” Mundy does not say this, but one story had it named after a chocolate cake because that was what the Polish mathematicians were eating at a restaurant when they outlined their theoretical solution to the German cipher back in 1932. Anyway, on page 135, it appears as a “bomby”—gratefully just that one time. It is an example of the many empty files in Mundy’s knowledge warehouse. 


Mundy says three times that making codes is “the best possible training for learning how to break them.” (page 75) That is not true. It is true that learning the history and application of codes and ciphers is basic to cryptology. But making up arithmetic problems will not teach you how to solve them. The fact is that experts break the codes and ciphers of amateurs specifically because tyros are inept at cracking. Mundy had never done the work herself. This was all new to her. 


So was World War II. We all commonly see this as the three Allied powers against the three Axis powers. We also accept the USSR as our ally and still consider the French to have been in “the free world” (page 308) even though French reactionaries had spent four years helping the Germans to round up Jews. Mundy never questions it, even in the context of a war in which the British and American intelligence groups did not always trust each other. As a recent ally of Germany, the USSR was never to be trusted. She mentions the America First movement only in passing. Therefore, Mundy does not explore the motivations of the women who asserted themselves to join the civilian government defense efforts before Pearl Harbor. 


I accept as an assumption that Mundy is not comfortable with firearms and she has never flown an airplane. So, she quickly passes over the firearms qualifications that several women earned, among them Louise Pearsall, (page 273), and Fran Steen (page 191) who also earned a private pilot certification while working as a cryptanalyst (page 191). The author just does not appreciate those accomplishments.


Unlike the reviewers for the mainstream media I spent two weeks with this book. Despite the many reasons to put post-its on pages, this was not painful. Mundy writes well. I was pleasantly surprised to learn that among the cryptanalysts were philosopher William Van Orman Quine, actor Tony Randall, classicist Richmond A. Lattimore, and contract bridge mavin Oswald Jacoby (page 181). It was also interesting to get the backstory on William Friedman. I always accepted his being the master cryptanalyst who singlehandedly broke Purple. In fact, Mundy says (and my wife concurs) that Elizabeth was the brains. She introduced him to crypto. And, of course, this book is the story of the women who really broke Purple. So, there is a lot here. 


But the untold story of the Code Girls was always hidden in plain sight. In 1996, when I was working for the US DoD back home in Cleveland, Nida Glick, my mother’s Latin teacher (who had been the language department chair when I went to the same high school), passed away. Her obituary in the May 6 Plain Dealer showed her in her Coast Guard uniform from World War II when she served as a codebreaker. 


Mundy’s experience with Politico, The Atlantic, and The Washington Post, and her work on behalf of Michelle Obama reflect her engaging and compelling narrative style. However, pop culture books and magazines are different from history books. I know from personal experience that as painful as it can be, a newspaper can always print a correction or even a retraction. With books, the errors and omissions are more permanent and revealing. 

Also, even if the New York Times and Kirkus were not pre-disposed to ladle praise on this work, the fact is that professional reviewers also bang out copy on deadlines. So, fact checking is not always possible, even if it is wanted by the editors.


Historians labor under a special conflict of norms different from the other sciences. (My Marxist professors easily convinced me that history is a science.) If a historian judges the people of the past by the standards of the present, no one looks good. If you accept the cultural standards of another time and place, then you fail to be objective. In anthropology that is called the error of going native. 


Mundy acknowledges that many of these women were born in or around 1920 when American society was changing. The social revolutions in norms of behavior were more dramatic than the material progress of the 19th century. These women left their old world in 1940 and then left it behind irretrievably in 1945. Some did well. Ann Caracristi became the first woman deputy director of the NSA. After years of peak experience, and then dumped into an environment where the only pressure was to conform, others suffered the same PTSD as other combat veterans and never reintegrated completely to civilian life. Some took the hard road down. Others recovered. It is a complex story and Mundy tells it well enough.



The Second World Wars by Victor Davis Hanson 

Codes and Coins 

A Successful Imitation of Alan Turing 

2nd Lt Frances Slanger: American Nightingale 

World War II Sweetheart Dance 

The Wise Men 

Saturday, April 17, 2021

Amateur Astrophotography is Baloney

“Are visual observers a dying breed?” is a topic on The Sky Searchers discussion board. It does not refer to the book The Last Stargazers by Emely Levesque but to the trend among amateurs to invest in cameras and software for capturing and processing images. The work also requires a special telescope—now very common—generally a larger objective eight to 14 inches (200 to 350 mm) with an equatorial mount with a tracking motor to keep the instrument aligned to the target for hours. Some astrophotography (AP) enthusiasts use traditional 35 mm digital single lens reflex (DSLR) cameras though charge coupled devices (CCD) and single-chip cameras are also common. Then, there is the post-processing. After the computerized (or computer controlled) camera snaps hundreds of long exposures (one to three minutes each), the images are “stacked” in software. Then the images also are manipulated with color filters to create a pleasing depiction of the object. To me, that is art, not science.

They decide in advance what they want for the product and they manipulate the data to achieve the effects they desire.

The Journal of Irreproducible Results was a humor magazine for scientists. Launched as a mimeographed samizdat in 1955, it remained popular for over 45 years. “A Drastic Cost Saving Approach to Using Your Neighbor’s Electron Microscope” by Aalbert Heine offered a photomicrograph that was captioned “Fig. 1: A eutectic mixture of quartz and plagioclase … Fig. 2: A cross section through the skin of a peripatus … Fig. 3: The surface of a root hair of a quadruploid species of crabgrass. … Fig. 4: Fragment of a hickory ax handle. …” 

And, so too, could these pretty pictures be almost any kind of target. Without spectroscopic data—or even right ascension, declination, and local time—the reader, reviewer, or following researcher has no way to gauge the validity of the data. And, more to the point, no objective way to reproduce it. These are irreproducible results. 

Interpretations of the Rosette Nebula (Caldwell 49)

I do believe that photography is a powerful tool for the science of astronomy. On the same amateur discussion boards, some observers will post a snapshot along with their narrative. The photograph is a valid record. Early in its development spectroscopy came to depend on photography to provide the primary record. Photographic records of spectra have been replaced by digitized data, but analog images of the spectral lines remain important and valuable. 

The stars are pretty at any magnification.

On that basis, I just signed up for a class in astrophotography. As an observer without AP equipment, I paid the same price as the other client learners who will be bringing their gear to the night of classroom training (virtual), the night of observing at the Austin Astronomical Society dark sky site, and the follow-up class in post-processing. The cost was $250. By comparison, I also paid $130 for a class in astrophysics in order to learn the vocabulary and concepts of astronomy for my volunteer work as an editor with the American Astronomical Society.




Emily Levesque and The Last Stargazers 

Is Physics a Science? 

Backyard Astronomy 

Turn Left at Orion 

Redshift: Six Years with Amateur Astronomy 

The Perfect Machine 


Tuesday, March 30, 2021


Maria Mitchell deserves to be honored on the newest series of U.S. circulating commemorative quarter dollars, 2022-2025. She was the first American woman to be a professional astronomer, and one of the first American astronomers acknowledged by both European and American academic communities. An informally educated autodidact, she became the first professor of astronomy at Vassar. The spotlight of fame fell on her when she was the first person in history to discover a comet using a telescope. The year was 1847. She was 29 years old. For her work, she won the gold medal offered by the King of Denmark. 

Her name is pronounced “ma-RYE-ah” (like the wind in Paint Your Wagon). Born on August 1, 1818, she was raised on Nantucket where her father was a naturalist and banker. Her parents, William and Lydia (Coleman) Mitchell, were Quakers and her commitment to social equality was aligned to their faith. Largely self-taught, she attended classes at local schools, one of them run by her father. She studied mathematics (of course) and also learned astronomy, surveying, and navigation. One of her father’s occupations was setting the chronometers of whalers and other ships that harbored at Nantucket, and she did the work when he was away on the mainland, often at Harvard College.[1]

Annie J. Cannon
dollar coin 2019
 When she was 12, she and her father calculated an exact position of their home by measuring the Great Solar Eclipse of February 12, 1831. Two years later, she was setting chronometers for ship captains. When her father won a contract to work for the US Coast Survey, she accompanied him. 


Mitchell owned a Dollond-style achromatic ship’s telescope (3-inch aperture; 46-inch focal length).[2] In 1847, the family lived in the Pacific Bank Building on Main Street in Nantucket because her father was the head cashier there. She observed from the roof. On October 1, she saw a faint star that was new to her; and she soon verified that it was not listed in the tables and charts. Tracking it, she determined that it was a comet publishing her calculations of its orbit in Silliman’s Journal of Yale (later known as the American Journal of Science). That helped to secure her claim to primacy of discovery and the winning of the gold medal.[3] 


Email to the Board of the American Astronomical Society
recommending the Maria Mitchell Quarter.
(As with several others to astronomy leaderships, no replies have come.)

Later, she moved briefly to Boston and computed the orbit of Venus for the US Nautical Almanac [1]. She served as the librarian of the Boston Athenaeum and then toured Europe on her own, meeting with John Herschel, George Biddle Airy, and other astronomers. She returned to the States, and in 1865 she was appointed professor of astronomy at Vassar College, which, ironically enough paid her less than other professors, though not for her lack a university degree. She took her students to observations of the transit of Venus and solar eclipses (1869, 1878, and others) in Nebraska and Colorado. 

20 Prominent American Women To Be Honored On US 2022-2025 Quarters

Public Law No: 116-330 (01/13/2021 here 


The Circulating Collectible Coin Redesign Act of 2020

“(C) SINGLE PROMINENT AMERICAN WOMAN ON EACH QUARTER DOLLAR.—The design on the reverse side of each quarter dollar issued under this subsection shall be emblematic of the accomplishments and contributions of one prominent woman of the United States, and may include contributions to the United States in a wide spectrum of accomplishments ...

Nominations for women to be honored on the new series of coins are being curated in part by the Smithsonian Women’s History Initiative ( and



[1] The Maria Mitchell Foundation biography here:

[2] (of course; but follow the footnotes)

[3] “Maria Mitchell at 200: a pioneering astronomer who fought for women in science, “ Richard Holmes, Nature, 26 June 2018, here:

Other Resources
“A Woman in Eclipse: Maria Mitchell and the Great Solar Expedition of 1878,” by David Barron, here:
“This Month in Astronomical History: Maria Mitchell,” History of Astronomy Division, American Astronomical Society, here:



She’s Such a Geek! 

Females and Women 

Bringing Philosophy to Athens: Aspasia of Miletus 

Hypatia of Alexandria 

The Madame Curie Complex 


Wednesday, March 17, 2021

An Online Class in Astrophysics

I recently completed a survey in astrophysics offered by the École polytechnique fédérale de Lausanne through edX, a program created by Harvard and MIT and now involving many other institutions. I recommend this class with serious reservations. If you want a structured experience in learning astrophysics on your own, this can help. I found the content informative, challenging, and edifying. However, the presentation was often marred by careless transcription and poor translation of the lectures. 

 I do grant that as listed, Physics 209, this is about what I would expect from an American university for a sophomore class in physics, though for non-majors. Calculus is at a minimum here. Once a week or so, I did spend an hour with one math problem among three or four multiple choice. If you did well at “Conceptual Physics” and have a head for algebra, this is a solid survey of topics in astrophysics. 


Nominally, the course takes seven weeks to work through seven chapters which are presented as 27 lectures and quizzes. Each lecture is about 20 to 35 minutes. So, this is about a fourth of a semester of effort, all in all. There is a thin textbook that you can download as a PDF. I found it helpful and referred to it often. 


I took the course for certification. So, I paid the registration fee of USD 139. Personally, I need that kind of motivation. If I had not been financially invested in the outcome, I would have walked away from it—which I also considered. More than once, I almost cut my losses and left the money on the table. Instead, I toughed it out and actually earned the certificate of completion a little more than halfway through the class because at that point, it was arithmetically impossible for me to fail. I viewed all of the lectures and completed all of the quizzes. They drop your three lowest scores. With that, I averaged 90%.


The grading system is simple. Each video is followed by several quizz, either multiple choice questions or questions requesting a numerical answer. In most cases it is possible to try 2-3 answers before giving the final answer. You qualify for the certificate with at least 50% of correct answers for at least 19 out of the 22 quizz that we propose. 


When a numerical answer is required, usually, a 10% error bar is included in the calculation, more if it's an order of magnitude estimate.


Week 1: General introduction - Kepler's Laws - Virial theorem.

Week 2: Radiation processes - Line radiation - Black body - Measuring radiation.

Week 3: Doppler-Fizeau effect and astrophysical applications - Interstellar and intergalactic radiation - Strömgroen sphere - Absorption/emission - Color index - Tidal forces. 

Week 4: Roche limit - Comets - Planetary energy balance - Planetary atmospheres - 

Week 5: Stellar formation - Stellar classification - Stellar evolution. 

Week 6: The galaxies - Rotation of the Milky Way and Oort constants - Dark matter.

Week 7: Fundamentals of cosmology - Distance ladder - Gravitational lensing.


Length: 7 Weeks

Effort: 3–4 hours per week

I kept two notebooks, in fact. The first is set of Word files made from the lecture notes provided. The other is a spiral bound that I also have for working astronomy problems from books that I buy or borrow from the library. I captured the solutions to all of the answers that I missed and some that I guessed right and put those in either or both as needed.


First, and foremost, I do not have the mindset of a physicist or I would have become one a long, long time ago. So, for some problems, I had to see how it was done, what approach was needed, which contexts were relevant, where the equations of solution had to come from. So, that was learning. I missed a couple of others just because I did not understand what was being asked. 


Just below halfway on the left
find "stronger in radius"
for "Strömgren radius."

I also invested a lot of time into correcting the transcripts of the lectures. The English language speaker did not understand the material he was reading. Often, he spoke “v” for the Greek letter nu and “p” for rho, and so on. Sometimes he left symbols out entirely. Once, he spoke “proton” for “photon.” The course was replete with such problems. In one way, the careless transcription of text gave me the opportunity to read and review the lecture in detail. I formatted paragraphs and formatted equations. The fact remains that some lecture notes lacked any punctuation.


A more subtle difficulty was in the differences between sentence structure in French and English. The English speaker paused when the professor did, even though the thoughts presented as subordinate clauses, parenthetical comments, noted asides, or dependent clauses were strung differently in the two languages. 


Despite the fact that the course was supposedly monitored by a professor and three assistants, in point of fact, no one monitored the course. When I finally tried to send an email the EPFL coordinator, the message bounced as undeliverable. So, you are on your own here. 


Through a YouTube channel created by a maths boffin named Tibees. (Tibees

An MIT final exam in astrophysics”), I found MIT's open courseware. She misidentified this as a final examine in astrophysics from MIT. I followed the links and found that it was merely plain old astronomy, which, apparently, at MIT is astrophysics. (See here.  And they have a lot more if you want to work on your own through a structured course.) Anyway, most of these topics were touched on by at least one quiz question in the EPFL course though in much less depth.




Steven Weinberg on Gravity Waves 

Measuring Your Universe: Alan Hirshfeld’s Astronomy Activity Manual 

Newton and Leibniz 

The Solstice Seasons 

Seeing in the Dark: Your Front Row Seat to the Universe 


Saturday, March 6, 2021

Unforgotten Sisters: Early History of Women Astronomers

Most readers will recognize Hypatia of Alexandria and Hildegard von Bingen. However, En-Hedu-Anna of Babylon, Theano the Pythagorean, and Wang Zhenyi of 18th century China will likely be among the many newly met. Sophie Brahe and Elizabetha Hevelius will be known for their family names, though in our common histories, they have been eclipsed by the men in their lives. It remains true that their own accomplishments shine apart. That is also true of Caroline Herschel. It depends on who writes the histories and how diligently the reader follows the threads of fact. 


A previous version of this article appeared in the April 2020 issue of Sidereal Times of the Austin Astronomical Society. It is available here:

The Unforgotten Sisters: 
Female Astronomers and Scientists 
Before Caroline Herschel
by Gabriella Bernardi 
(Springer Praxis, 2016, 179 pages

Contrary to the title, Caroline Herschel herself is among the 25 astronomers whose lives are outlined. Caroline Herschel and Mary Somerville were both inducted as honorary members of the Royal Astronomical Society in 1836. Thus, Somerville (1780-1872), who also is chronicled here, was a younger contemporary rather than living “before” Herschel (1750 to 1848). Even so, here are 25 women who worked in astronomy before the modern era. Each chapter includes a summary of achievements, commentaries about the woman and her work from her own society, and some “curious facts” about them. 


The author puts forward Christine Kirch as the first woman to be a professional astronomer. Starting in 1776, she was paid 400 thalers a year by the Berlin Academy of Prussia. Christine Kirch was the daughter of Gottried Kirch and Maria-Margaretha Winkelmann-Kirch. Winkelmann-Kirch has her own entry. She worked and socialized among astronomers, including Christoph Arnold Sommerfeld, before meeting Gottfried Kirch. She was his third wife and 30 years his junior. Their children were raised in the family business. Following the death of her husband, Winkelmann-Kirch was offered a post in Saint Petersburg after showing sunspots and other phenomena to the Tsar, but she refused because her son, Christfried, accepted a post at the Berlin Observatory. She died three years later. 


According to the publisher’s website, the title of the book is a turn on a line from a poem by Siv Cedering. The poem is an imaginary letter from Caroline Herschel; and you can find it on the Space Telescope Science Institute website under the tab for “STScI Research” which will take you to their Caroline Herschel Visitor Program. The program brings scientists to “act as mentors to junior scientists at the institute, especially women and other underrepresented groups.” I found the website to have been newly rebuilt. 


is more direct. 

The poem begins: 

“William is away, and I am minding
the heavens. I have discovered
eight new comets and three nebulae
never before seen by man…”


This book is a good a resource. Knowing for whom to search, the histories can follow more easily. However, it is replete with small problems in grammar, style, and typography. In one subhead the “Curious Facts” are “Curios.” Other subheads appear as “Curiosity” without actually showing this to be an attribute of the astronomer herself. Writing about the sisters Christine Kirch and Margarethe Kirch, Bernardi calls Christine the eldest of the two. Clearly, English was not the author’s first language; and the editors at Springer let a lot go by. 


For modern history, probably the best portal is the Astrophysical Data System of the Harvard at There are archived citations and full text of journal articles and internal reports by Williamina Fleming, Annie Jump Cannon, and many less generally known.




The Scientific Method 

Astronomical Symbols on Ancient and Medieval Coins 


When Old Technologies Were New 


Friday, March 5, 2021

Emily Levesque and the Last Stargazers

This book is mislabeled. If observational astronomy is in any danger as a profession it is from overpopulation as researchers line up to use the world’s observatories. This is just a bunch of cute stories. In not one of them has a dispirited stargazer turned to another profession for lack of opportunity or (worse) from a lack of interest in a field long closed to discovery. No one is vanishing here.

The Last Stargazers: 
The Enduring Story of 
Astronomy’s Vanishing Explorers
by Emily Levesque 
Source Books, 2020
Seldom do I not finish a book. Even less often do I give a negative review. I also am fully cognizant of the limitations of “the boy brain.” Men are too easily characterized by our passions for food, sex, and combat. That said, as the father of a daughter, it was too easy for me to see the girl brain at work here: I’m cute; I’m smart; Everyone likes me. I am sure that she is and we do. Halfway through, I just turned the pages until the end.


Emily Levesque has been granted awards for her ground-breaking research into red supergiant stars. She also advocated successfully to have the Physics Graduate Record Examination dropped as a basic requirement for astronomers and physicists seeking admission to graduate school. It was a stellar victory, but from my point of view 50 years late. See, The Tyranny of Testing by Banesh Hoffmann (1962), which I learned about in 1966 from Ayn Rand’s Objectivist Newsletter. 

Levesque writes well. Her modern style is close enough to literature that her neologisms do not detract from her narrative. But the narrative just stopped being interesting halfway through the book. It was recommended on an astronomy discussion board that I participate in. So, I bought it without hesitation. 


Except for the fact that their mirrors are larger, these folks only do what any amateur astronomer does: put up with cold and heat, animals and instruments, just to get a look at a star (or planet, etc.). As for the observing, amateurs also engage as radio astronomers. Photography and spectroscopy have long been tools. And we publish our results. 

The key difference there is that for amateurs on discussion boards, peer review is after the fact, whereas for an academic researcher, peer review is a form of censorship. Moreover, it so happens that in astronomy, peer review is a form of vanity press. Researchers must pay journals to publish their works—though only after the report has been approved. Levesque is silent on that.




Focus on Simon Georg Ploessl 

Cosmos: A Spacetime Travesty 

Questions about "A Brief History of Time"

Females and Women 

U.S. Patent Law Does Not Add Up 

Monday, March 1, 2021

In Like a Lion

Sunny has adapted well to the routine. She no longer exhibits so many symptoms of PTSD. Now she likes being petted. She is still an indoor cat, though she has been outside a couple of times. She found the underside of the back porch and the hole in the fence. But she came home quickly at the sound of food. 


She discovered the other cat in the refrigerator door and the TV when it is off. I keep exercise mats back there and when I reached over the TV to pull them out her worldview shifted. But she accepts the TV for whatever it is. Much of my perception of cats as pets is based on Fantastic Planet, an animated adult presentation about humans on a planet orbiting Sirius. (Wikipedia here. ) That is from the cat’s point of view, perhaps. 


From our side, I consider Cordwainer Smith’s “Game of Rat and Dragon” and Fritz Leiber’s “Spacetime for Springers.” Larry Niven’s Ringworld Trilogy had Speaker-to-Animals, and we did have cats named Squeaker-to-Animals and Kzinti Warfish, but the cat(s) in that series are  anthropomorphized. 


Previously on Necessary Facts


Green Lantern Outshines Green Hornet 

Captain America 

When Worlds Collide 

Superman: American Alien 

Sunday, February 21, 2021

Winter Happened

On Monday, 8 February, I saw an early honeybee on an early dandelion. On the 15th, temperatures were in the single digits. The state of Texas suffered a winter storm from the Panhandle to the Rio Grande. We were in one square mile that did not lose electrical power. However, by Wednesday night, the water quit. 

Fortunately, on Monday, we had filled kitty litter pails and put them in the bathrooms for flushing. (We keep them for household moves because they store electronics, glassware, etc., very nicely.) But by Friday, when it warmed up, I refilled them all with roof runoff, again for flushing. We had enough bottled water. We keep 10 gallons in glass and refill six heavy plastic gallons for daily use. We have two Brita filters, one caraffe and one for the faucet. And we still have plenty of dry, packaged, and frozen food. Gratefully, we did lose power, though we could have put the refrigerated and frozen food outdoors for a few days, as other people did. And we have a barbeque grill and five bags of charcoal in the garage.

2004 Kingsley, Michigan, Halfway to the North Pole (45 N)
Roof rakes for when then snowfall threatens the structure.

We expect the "boil water" notices to be lifted in a couple of days. Just in case, though, I started tap water boiling on the stove.

Emergency preparedness is a state of mind and a lifestyle habit. I was fortunate to have worked a project for the Texas Department of Public Safety Division of Emergency Management in 2014 and then go from there to a project at the Texas Military Department which took me into the Texas State Guard, which included 15 or 20 online classes from FEMA, and half a dozen live exercises, culminating in three deployments. Aristotle called deep learning "second nature."

Hurricanes, tornadoes, floods, wildfires, snowstorms, my nightmare scenario is that the Permian Basin is going to sink 500 feet and become a lava field.

Previously on Necessary Facts

CERT: Community Emergency Response Team 

Hurricane Tejas 

The Next Hurrican Harvey 

Volunteering in an Emergency: What to Expect