astronomy

Samuel Alfred Mitchell

Samuel Alfred Mitchell is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Samuel Alfred Mitchell rather than just read about it. In short: Samuel Alfred Mitchell (April 29, 1874 – February 22, 1960) was a Canadian-American astronomer who studied solar eclipses and set up a program to use photographic techniques to determine the distance to stars at McCormick Observatory, where he served as the director. Early years Mitchell was born in Kingston, Ontario, the son of John Cook and Sarah Chown Mitchell, the sixth of ten children to grow up in the Mitchell…

Key takeaways

Samuel Alfred Mitchell belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Samuel Alfred Mitchell to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Samuel Alfred Mitchell from memory before moving on to harder problems.

Reference excerpt

Samuel Alfred Mitchell (April 29, 1874 – February 22, 1960) was a Canadian-American astronomer who studied solar eclipses and set up a program to use photographic techniques to determine the distance to stars at McCormick Observatory, where he served as the director.

Early years Mitchell was born in Kingston, Ontario, the son of John Cook and Sarah Chown Mitchell, the sixth of ten children to grow up in the Mitchell home. Mitchell's father (a tenth child) emigrated to Canada from St. Austell, Cornwall. His mother, born in Kingston, was the tenth child of parents who emigrated to Canada from Devonshire. At age twelve Mitchell went off to Kingston Collegiate Institute. From there, he went on to Queen's University where he received his Masters of Arts in mathematics in 1894. While at Queen's University, he acquired knowledge of the techniques of an astronomical observatory when he was asked to care for the astronomical instruments of the university. Upon encouragement from his math professor, Nathan Dupuis, he left in 1895 for Johns Hopkins University to study math under Simon Newcomb, only to find Newcomb retired. Thomas Craig was the new head of mathematics and Mitchell also began study under Charles Lane Poor, the head of astronomy. Poor was an excellent teacher and Mitchell was inclined to follow astronomy from that point on. Mitchell was awarded an astronomy assistantship for his second year at JHU and continued until he received his PhD in 1898 with his thesis published in the Astrophysical Journal, which included a discussion of the amount of astigmatism of a concave grating. While at Hopkins, his astronomy duties consisted of caring for the astronomical transit instrument and the clocks in the little observatory behind the physics laboratory, and the 9.5-inch refractor in the dome of the laboratory roof.

Yerkes Observatory Following receipt of his doctoral degree, Mitchell set out for the brand new Yerkes Observatory in Wisconsin where he began work as a research student in 1898. Though he enjoyed his work at Yerkes, he was enticed to move away and became an instructor in astronomy at Columbia University in June 1899. Over the fourteen years he was at Columbia, Mitchell taught undergraduate courses in descriptive astronomy both at Columbia and later for girls from Barnard College, a year long course in geodesy for third year students, which continued into a first semester fourth year course, and a six-week summer camp for civil engineers.

Eclipse work In 1900, he took what would be for him the first of ten eclipse expeditions. The May 28, 1900 eclipse took him to Griffin, Georgia with the United States Naval Observatory. Mitchell became a world-renowned authority on solar eclipses through his numerous expeditions, including trips to: Sawah Loento, Sumatra in the Dutch East Indies (May 18, 1901), Daroca, Spain (August 30, 1905), Baker, Oregon (June 8, 1918), San Diego, California (September 10, 1923), Van Vleck Observatory, Middleton, Connecticut (January 24, 1925), Fagernas, Norway (June 29, 1927), Niuafoou or "Tin-Can" Island, Tonga, in the South Pacific Ocean (October 22, 1930), Magog, Quebec, Canada (August 31, 1932), and Kanton Island, Kiribati (June 8, 1937), this time as the scientific leader of a National Geographic Society Expedition. An article entitled "Nature's Most Dramatic Spectacle" by Mitchell appeared in the September 1938 edition of National Geographic Magazine. These ten expeditions allowed him to write Eclipses of the Sun, summarizing his work on solar flash spectra, first published in 1923 and produced through five editions (5th edition, 1951). On the 1918 Oregon and the 1925 Connecticut eclipses, Mitchell was accompanied by the artist Howard Russell Butler (1856–1934), whose paintings of totality graced the old Hayden Planetarium of the American Museum of Natural History for many years.

Parallax work and Leander McCormick Observatory Mitchell went back to Yerkes for the summers of 1909, 1910 and 1911 and then returned for a fifteen-month sabbatical in 1912 and 1913. Frank Schlesinger first demonstrated the technique of determining stellar parallaxes photographically at Yerkes in 1905, and Mitchell (along with Frederick Slocum) carried out research applying the technique, publishing their results in 1913. At that point, he was offered the directorship at the Leander McCormick Observatory at the University of Virginia. Mitchell spent much of his time and energy as director coming up with funds for running the observatory and paying staff and graduate students. Mitchell started the use of photographic plates with the visual 26-inch refractor shortly after his arrival at the University of Virginia. He became well known for his work on stellar parallaxes and photometry. Dr. Mitchell was liked by faculty and students alike, known for helping to bring prestige to the university.

Society Memberships Mitchell was elected Director Emeritus in 1945 with a wealth of academic and scientific honors attributed to him. He was a member of the following societies: National Academy of Sciences (elected in 1933, elected to council in 1940, awarded James Craig Watson Medal in 1948), American Association for the Advancement of Science (vice-president in 1921), American Astronomical Society (Vice-president 1925–1927), Royal Astronomical Society (fellow and associate), International Astronomical Union (president of Commission on Solar Eclipses and Commission on Stellar Parallaxes and Proper Motions), American Association of University Professors (chairman of Committee A, on Academic Freedom and Tenure), American Philosophical Society, and the American Academy of Arts and Sciences.

Ice hockey career

While studying at the Johns Hopkins University Mitchell played on the university ice hockey team. In February 1896 he was a part of the Johns Hopkins team that played against the Yale University team in the first two intercollegiate ice hockey games in the United States. The Johns Hopkins team also played six games against the Baltimore Athletic Club during the 1895–96 season, and one game against an All-Washington aggregation. As an ice hockey player Mitchell played predominantly at the point position which is an archaic ice hockey position equivalent to a defensive defenseman today. Mitchell also played with the university team during the 1896–97 and 1897–98 seasons.

Family

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Samuel Alfred Mitchell

Start with the simplest possible case. Write down what Samuel Alfred Mitchell claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Samuel Alfred Mitchell before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Samuel Alfred Mitchell ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Samuel Alfred Mitchell

In research: Samuel Alfred Mitchell appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Samuel Alfred Mitchell in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Samuel Alfred Mitchell is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1874 births, 1960 deaths, American astronomers, so understanding it makes those chapters shorter.
In everyday life: Look for Samuel Alfred Mitchell outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Samuel Alfred Mitchell in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Samuel Alfred Mitchell means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Samuel Alfred Mitchell out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Samuel Alfred Mitchell in simple terms?

Why does Samuel Alfred Mitchell matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Samuel Alfred Mitchell?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Samuel Alfred Mitchell.