astronomy

Johann Georg Hagen

Johann Georg Hagen 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 Johann Georg Hagen rather than just read about it. In short: Johann (John) Georg Hagen (March 6, 1847 – September 6, 1930) was an Austrian Jesuit priest and astronomer. After serving as Director of the Georgetown University Observatory he was called to Rome by Pope Pius X in 1906 to be the first Jesuit director of the new Vatican Observatory.

Key takeaways

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Reference excerpt

Johann (John) Georg Hagen (March 6, 1847 – September 6, 1930) was an Austrian Jesuit priest and astronomer. After serving as Director of the Georgetown University Observatory he was called to Rome by Pope Pius X in 1906 to be the first Jesuit director of the new Vatican Observatory. Father Hagen was also the spiritual director of Maria Elizabeth Hesselblad (1870-1957), who was baptized by him on August 15, 1902 and eventually was canonized on June 5, 2016 by Pope Francis.

Biography

Early life Johann Georg Hagen was born in Bregenz, Austria on 6 March 1847, the son of a school teacher.

Entering the Jesuit Order Johann entered the Society of Jesus, commonly known as the Jesuits, in Gorheim, Germany in 1863. He attended the Jesuit College Stella Matutina in Feldkirch, Austria and also studied mathematics and astronomy at the University of Bonn and the University of Münster. He volunteered for the ambulance service in the Franco-Prussian War, but was struck with typhoid fever.

Expulsion On July 4, 1872, Otto von Bismarck, chancellor of Germany, expelled the Jesuits from the German Empire. Johann left for England where he was eventually ordained into the priesthood.

Emigration to US In June 1880, he left England for the United States. There he began teaching at Sacred Heart College in Prairie du Chien, Wisconsin. There he cultivated his interest in astronomy and built a small observatory for making astronomical observations. In Wisconsin, he became a naturalized citizen. He was called to serve as the Director of the Georgetown University Observatory in 1888. There he continued his research and published numerous articles and texts. He contributed several articles on astronomical topics to the Catholic Encyclopedia.

Vatican Observatory In 1906, John was called by Pope Pius X to take charge of the Vatican Observatory in Rome. He died in Rome on September 6, 1930.

Research Hagen is also noted for his study of variable stars. His survey was published in his Atlas Stellarum Variabilium (1890–1902). In mathematics, the Rothe–Hagen identity is named after him; it appears in his three-volume 1891 publication, Synopsis of Higher Mathematics. At the Vatican observatory, he reported a dark nebula that he could not photograph in 1931. This object is known as the Hagen cloud. Modern astronomy has discarded the existence of that nebula and has attributed it to inconsistencies in visual perception.

Honors and awards The crater Hagen, 55 km in diameter, on the far side of the Moon is named after him. The asteroid 562971 Johannhagen is named after him.

Publications Atlas Stellarum Variabilium [Atlas of Variable Stars] (in Latin). Berlin: Felix L. Dames. 1890–1908. with G. A. Fargis: The photochronograph, and its applications to star transits. Georgetown, D. C.: Georgetown College Observatory. 1891. Synopsis der höheren Mathematik. Vol. 4 vols. Berlin: F. L. Dames.Vol. 1: Arithmetische und algebraische Analyse. 1891.Vol. 2: Geometrie der algebraischen Gebilde. 1894.Vol. 3: Differential- und Integralrechnung. 1905.Vol. 4: Differentialgeometrie der Ebene und des Raumes. 1930. Index operum Leonardi Euleri. Berlin: F. L. Dames. 1896. Hagen, J. G. (1900). "On the history of the extensions of the calculus". Bull. Amer. Math. Soc. 6 (9): 381–390. doi:10.1090/s0002-9904-1900-00733-6. MR 1557730. La rotation de la terre, ses preuves mécaniques anciennes et nouvelles. Rome: Tipografia Vaticana. 1911.

Illustrations

Worked examples

Example 1 — a first encounter with Johann Georg Hagen

Start with the simplest possible case. Write down what Johann Georg Hagen 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 Johann Georg Hagen 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 Johann Georg Hagen 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 Johann Georg Hagen

In research: Johann Georg Hagen 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 Johann Georg Hagen 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: Johann Georg Hagen is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1847 births, 1930 deaths, 19th-century American Jesuits, so understanding it makes those chapters shorter.
In everyday life: Look for Johann Georg Hagen 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 Johann Georg Hagen in 20 minutes

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Frequently asked questions

What is Johann Georg Hagen in simple terms?

Why does Johann Georg Hagen 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 Johann Georg Hagen?

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 Johann Georg Hagen.