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 

at https://www.congress.gov/bill/116th-congress/house-bill/1923/text.

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 (https://womenshistory.si.edu and WomensHistory@si.edu).



[1] The Maria Mitchell Foundation biography here: https://www.mariamitchell.org/about-maria-mitchell

[2] https://en.wikipedia.org/wiki/Maria_Mitchell (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: https://undark.org/2017/08/17/wilo-maria-mitchell-astronomer-eclipse/
“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: http://austinastro.wildapricot.org/resources/Documents/ST%20Archive/ST202004.pdf

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. 

The URL http://www.stsci.edu/institute/smo/visitor-programs/caroline-herschel/poem

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 https://ui.adsabs.harvard.edu. 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. 

  • https://en.wikipedia.org/wiki/Emily_Levesque
  • https://www.emlevesque.com
  • https://thelaststargazers.com/about-the-author/

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