astronomy

Marie-Jeanne de Lalande

Marie-Jeanne de Lalande 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 Marie-Jeanne de Lalande rather than just read about it. In short: Marie-Jeanne Amélie Lefrançois de Lalande (née Harlay; 1768 – 8 November 1832) was a French astronomer. She was a key collaborator to the works of Jérôme Lalande.

Key takeaways

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

Reference excerpt

Marie-Jeanne Amélie Lefrançois de Lalande (née Harlay; 1768 – 8 November 1832) was a French astronomer. She was a key collaborator to the works of Jérôme Lalande. Her reputation as a scientific woman was attested by an anecdote related to Carl Friedrich Gauss: In 1806, during a military campaign in Prussia, he declared he knew but one French woman that worked in science, Madame Lefrançois de Lalande.

Biography Marie-Jeanne Harlay was born in Paris in 1768, daughter of school teachers Jean François Harlay (born 1730) and Anne Elisabeth Cany (born 1744). Some early authors considered her the illegitimate daughter of Jérôme Lalande. Jérome Lalande taught Marie-Jeanne Harlay astronomy. Jérôme Lalande was said to have valued Harlay for her mathematical disposition. Michel Lefrançois de Lalande, nephew of Jérôme Lalande, also learned astronomy with his uncle and married Marie-Jeanne in 1788. Jérome Lalande referred to Michel Lefrançois and Marie-Jeanne de Lalande as his nephew and niece. Michel Lefrançois succeeded Lalande at the École militaire and carried out a large star survey with the help of his wife, but she was not listed among the authors. Marie-Jeanne and Michel Lefrançois de Lalande had four children. Their son Isaac Lefrançais de Lalande was named after Isaac Newton. Their second child, Caroline was named after Caroline Herschel, her birth date, 20 January 1790 being the first day a Comet discovered by Herschel was visible from Paris. Caroline died as an infant. Their third child Charlotte Uranie Lefrançais de Lalande was the goddaughter the astronomer Jean Baptiste Joseph Delambre and Charlotte of Saxe-Meiningen. Their fourth child was named Charles Auguste Frédéric Jérôme Lefrançais de Lalande. De Lalande lectured in astronomy in Paris. During the French Revolution, the chief of the Paris Observatory, Dominique, comte de Cassini, asked Marie-Jeanne for help. She taught Cassini's son and helped him make his first observations at the Collège de France. De Lalande and the Duchess Charlotte of Saxe-Meiningen were the only female astronomers that participated at the First European congress of astronomers in 1798. During the trip, the Duchess added the name Amélie to de Lalande's name. She died in Paris in 1832.

Works She calculated the Tables horaires de marine, which was published in Jerome Lalande's Abrégé de navigation historique théorique et pratique avec tables horaires (1793). These calculations earned Jérôme Lalande one of the medals of the Lycée des Arts for distinguished scholars and artists. Jérôme Lalande dedicated the award to Marie-Jeanne de Lalande. Her work was also published in Jérôme Lalande's annual almanac Connaissance des temps from 1794 to 1806. In 1785, in the preface to Astronomie des dames by Jérôme Lalande, he cites Marie-Jeanne de Lalande as one of the greatest female astronomers along Hypatia, Maria Cunitz, Elisabeth Hevelius, Émilie du Châtelet, Nicole-Reine Lepaute, Louise du Pierry, Caroline Herschel and Charlotte of Saxe-Gotha. In 1799, she established a catalog of 10,000 stars. She also collaborated on the writing of L'Histoire céleste française written by Lalande and published in 1801. The work indicated the position of nearly 50,000 stars.

Honors The multi-ring impact crater de Lalande on Venus was named after her.

References

Illustrations

Worked examples

Example 1 — a first encounter with Marie-Jeanne de Lalande

Start with the simplest possible case. Write down what Marie-Jeanne de Lalande 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 Marie-Jeanne de Lalande 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 Marie-Jeanne de Lalande 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 Marie-Jeanne de Lalande

In research: Marie-Jeanne de Lalande 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 Marie-Jeanne de Lalande 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: Marie-Jeanne de Lalande is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1768 births, 1832 deaths, 18th-century French astronomers, so understanding it makes those chapters shorter.
In everyday life: Look for Marie-Jeanne de Lalande 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 Marie-Jeanne de Lalande in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Marie-Jeanne de Lalande 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 Marie-Jeanne de Lalande out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Marie-Jeanne de Lalande in simple terms?

Marie-Jeanne Amélie Lefrançois de Lalande (née Harlay; 1768 – 8 November 1832) was a French astronomer. She was a key collaborator to the works of Jérôme Lalande.

Why does Marie-Jeanne de Lalande 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 Marie-Jeanne de Lalande?

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 Marie-Jeanne de Lalande.