science

Passage de Vénus

Passage de Vénus 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 Passage de Vénus rather than just read about it. In short: Passage de Vénus is a series of photographs of the transit of the planet Venus across the Sun on 9 December 1874. They were purportedly taken in Japan by the French astronomer Jules Janssen and Brazilian engineer Francisco Antônio de Almeida using Janssen's 'photographic revolver'.

Key takeaways

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

Reference excerpt

Passage de Vénus is a series of photographs of the transit of the planet Venus across the Sun on 9 December 1874. They were purportedly taken in Japan by the French astronomer Jules Janssen and Brazilian engineer Francisco Antônio de Almeida using Janssen's 'photographic revolver'. It is the oldest "film" listed on both IMDb and Letterboxd. A 2005 study of the surviving material concluded that all the extant plates made with the photographic revolver are practice plates shot with a model, and if any of the many plates successfully exposed during the eclipse have survived, their whereabouts are unknown.

Subject of the photos – 1874 transit of Venus

The 1874 transit of Venus, which took place on 9 December 1874 (01:49 to 06:26 UTC), was the first of the pair of transits of Venus that took place in the 19th century, with the second transit occurring eight years later in 1882. The previous pair of transits had taken place in 1761 and 1769, and the next pair would not take place until 2004 and 2012. As with previous transits, the 1874 transit would provide an opportunity for improved measurements and observations. Numerous expeditions were planned and sent out to observe the transit from locations around the globe, with several countries setting up official committees to organise the planning.

Filming the transit Due to the popularity of the event, numerous expeditions to over 80 locations were ventured, and many expeditions considered the best way by which to record the event. Frenchman inventor Janssen came up with the idea for a "revolver photographic". This was a large camera based on the Maltese cross mechanism, which is an important milestone in the development of cameras used to film movies. The revolver could take several dozens of exposures at regulated intervals on a daguerreotype disc.

See also The Horse in Motion, 1878 series of photographs History of film technology

References

External links Passage de Venus at IMDb Passage de Venus on YouTube Passage de Vénus is available for free viewing and download at the Internet Archive

Illustrations

Worked examples

Example 1 — a first encounter with Passage de Vénus

Start with the simplest possible case. Write down what Passage de Vénus 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 Passage de Vénus 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 Passage de Vénus 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 Passage de Vénus

In research: Passage de Vénus 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 Passage de Vénus 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: Passage de Vénus is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1870s photographs, 1870s short films, 1874 films, so understanding it makes those chapters shorter.
In everyday life: Look for Passage de Vénus 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 Passage de Vénus in 20 minutes

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

Frequently asked questions

What is Passage de Vénus in simple terms?

Why does Passage de Vénus 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 Passage de Vénus?

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 Passage de Vénus.