science

Tycho Brahe days

Tycho Brahe days is a science 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 Tycho Brahe days rather than just read about it. In short: In the folklore of Scandinavia, Tycho Brahe days (Danish: Tycho Brahes-dage; Norwegian: Tycho Brahedager; Swedish: Tycho Brahe-dagar) are days judged to be especially unlucky, especially for magical work, and important business transactions (and personal events). Tycho Brahe (1546–1601) was a Danish astronomer, astrologer, and alchemist and as such achieved some acclaim in popular folklore as a sage and magician.

Key takeaways

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

Reference excerpt

In the folklore of Scandinavia, Tycho Brahe days (Danish: Tycho Brahes-dage; Norwegian: Tycho Brahedager; Swedish: Tycho Brahe-dagar) are days judged to be especially unlucky, especially for magical work, and important business transactions (and personal events). Tycho Brahe (1546–1601) was a Danish astronomer, astrologer, and alchemist and as such achieved some acclaim in popular folklore as a sage and magician.

Origins The idea that certain calendar dates are lucky or unlucky is of ancient origin, going back as far as the Mesopotamian civilizations. Tables that identify lucky and unlucky days are sometimes known by their German category name Tagwählerei.

The Coligny calendar identifies certain calendar dates as lucky (mat) or unlucky (anmat). The Roman calendar marks many days and parts of others as dies nefasti, religiously unsuitable for the conduct of public business. Contemporary North America has a tradition that Friday the 13th is an unlucky day. It has been called a "pervasive form of divination" that "is found in all [current] societies which regulate their days and nights in [the conventional modern] calendric system[s]". The received idea concerning the origin of Tycho Brahe days was that

"Tycho Brahe, the celebrated Danish astronomer of the sixteenth and seventeenth centuries, was very superstitious, considering certain days in the year pregnant with misfortune, wherefore in Denmark, up to this very day, the laboring class call such days on which they happen to meet with some unfortunate accident, Tycho Brahe's days." In his travelogue A Poet's Bazaar, Hans Christian Andersen alludes to Tycho Brahe's death while living in exile, in Prague, observing that

"Denmark owns not even his dust; but the Danes mention his name in their bad times, as if a denunciation proceeded out of it: These are 'Tycho Brahe's days!' they say." Although no mention of the days now called Tycho Brahe days is actually found in any work of Tycho Brahe, They are still frequently referenced in almanacs and recur in Scandinavian folklore. In the Cyprianus tradition, Tycho Brahe days are considered unlucky for magical work; several of the spells in the Black Books of Elverum note that they should not be carried out on a Tycho Brahe day.

Days Based on the Julian calendar January 1, 2, 4, 6, 11, 12, 29 February 11, 17, 18 March 1, 4, 14, 15 April 9, 16, 17, 18, 19, 22, 29 May 10, 17, 18 June 6 July 17, 21 August 20, 21 September 16, 18 October 6 November 6, 18 December 6, 11, 18 These days were supposed to be unlucky to perform tasks such as getting married, starting a journey, or to fall ill on. Some versions claim that Tycho Brahe also identified several days as particularly lucky:

January 26 February 9 and 10 June 15 Some lists omit certain days, or add others; there is no standard list. Denmark was on the Julian calendar until 1700, when it switched to the Gregorian calendar.

Illustrations

Tycho Brahe days: This printed Cyprianus (Copenhagen, 1916) promises the list of Tycho Brahe Days. — This printed Cyprianus (Copenhagen, 1916) promises the list of Tycho Brahe Days.

Worked examples

Example 1 — a first encounter with Tycho Brahe days

Start with the simplest possible case. Write down what Tycho Brahe days claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, 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 Tycho Brahe days 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 Tycho Brahe days 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 Tycho Brahe days

In research: Tycho Brahe days appears in science 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 Tycho Brahe days 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: Tycho Brahe days is common in secondary-school and first-year university syllabi. It links to neighbouring topics Danish folklore, Luck, Norwegian folklore, so understanding it makes those chapters shorter.
In everyday life: Look for Tycho Brahe days 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 Tycho Brahe days in 20 minutes

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

Frequently asked questions

What is Tycho Brahe days in simple terms?

Why does Tycho Brahe days matter?

Because it connects several science 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 Tycho Brahe days?

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 Tycho Brahe days.