astronomy

Johannes Franz Hartmann

Johannes Franz Hartmann 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 Johannes Franz Hartmann rather than just read about it. In short: Johannes Franz Hartmann (11 January 1865 – 13 September 1936) was a German physicist and astronomer. In 1904, while studying the spectroscopy of Delta Orionis he noticed that most of the spectrum had a shift, except the calcium lines, which he interpreted as indicating the presence of interstellar medium.

Key takeaways

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

Reference excerpt

Johannes Franz Hartmann (11 January 1865 – 13 September 1936) was a German physicist and astronomer. In 1904, while studying the spectroscopy of Delta Orionis he noticed that most of the spectrum had a shift, except the calcium lines, which he interpreted as indicating the presence of interstellar medium. He was the director of the La Plata Astronomical Observatory, Argentina, from November 1922 to May 1934, and was also known under the name Juan Hartmann. He oriented the work of the observatory towards astrophysics and discovered the three asteroids of the main-belt, 965 Angelica, 1029 La Plata and 1254 Erfordia at La Plata between 1921 and 1932. His doctorate was from the University of Leipzig in 1891 on lunar eclipses. The lunar crater Hartmann on the far side of the Moon was named in his honor. Note, however, that the asteroid 3341 Hartmann was named after William K. Hartmann and is unrelated to him.

See also Hartmann mask, a tool to help focusing telescope

References

External links (in Spanish) Lista de cientificos Archived 2016-10-14 at the Wayback Machine Hartmann, Johannes Franz Archived 2016-03-03 at the Wayback Machine

Illustrations

Worked examples

Example 1 — a first encounter with Johannes Franz Hartmann

Start with the simplest possible case. Write down what Johannes Franz Hartmann 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 Johannes Franz Hartmann 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 Johannes Franz Hartmann 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 Johannes Franz Hartmann

In research: Johannes Franz Hartmann 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 Johannes Franz Hartmann 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: Johannes Franz Hartmann is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1865 births, 1936 deaths, 19th-century German astronomers, so understanding it makes those chapters shorter.
In everyday life: Look for Johannes Franz Hartmann 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “Johannes Franz Hartmann” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Johannes Franz Hartmann in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Johannes Franz Hartmann 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 Johannes Franz Hartmann out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Johannes Franz Hartmann in simple terms?

Why does Johannes Franz Hartmann 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 Johannes Franz Hartmann?

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 Johannes Franz Hartmann.