astronomy

John H. Day

John H. Day 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 John H. Day rather than just read about it. In short: John Hemsworth Osborne-Day (25 August 1909 – 24 April 1989 ) was a South African marine biologist and invertebrate zoologist who was born in Sussex and who died in Knysna. He is best known for his work on the taxonomy of Polychaeta and for his studies on the ecology of South African estuaries.

Key takeaways

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

Reference excerpt

John Hemsworth Osborne-Day (25 August 1909 – 24 April 1989 ) was a South African marine biologist and invertebrate zoologist who was born in Sussex and who died in Knysna. He is best known for his work on the taxonomy of Polychaeta and for his studies on the ecology of South African estuaries.

Career John Day received his BSc from Rhodes University in 1931, his PhD from the University of Liverpool and subsequently lectured at Durham University. In 1938 he was appointed as research assistant to Professor T. A. Stephenson in the Zoology Department of the University of Cape Town. During World War 2 he joined the Royal Air Force and become squadron leader in Bomber Command. He lost a leg after a bombing raid and received the Distinguished Flying Cross (United Kingdom) and bar. Following the War, John Day returned to the University of Cape Town and in 1947 was appointed head of the Zoology Department, a position he held until his retirement in 1974. He was a Fellow of the Linnean Society of London and Fellow of the Royal Society of South Africa. In 1967 John Day published his two volume Monograph on the Polychaeta of Southern Africa, and this publication is still a widely used identification tool to the major groups of these common and diverse marine worms. He also authored books on South African marine life and on estuarine ecology in South Africa as well as numerous journal articles. John Day described 190 species of polychaetes .

References

External links Simon, Carol A.; van Niekerk, H. Helene (2012). "A brief history of John Day". A guide to the shell-infesting spionids of South Africa. Retrieved 28 August 2019. Wilson, Robin S. (26 September 2019). "A Day for Worms on BHL". Biodiversity Heritage Library. Retrieved 29 July 2019.

Illustrations

Worked examples

Example 1 — a first encounter with John H. Day

Start with the simplest possible case. Write down what John H. Day 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 John H. Day 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 John H. Day 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 John H. Day

In research: John H. Day 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 John H. Day 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: John H. Day is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1909 births, 1989 deaths, 20th-century South African zoologists, so understanding it makes those chapters shorter.
In everyday life: Look for John H. Day 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 John H. Day in 20 minutes

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

Frequently asked questions

What is John H. Day in simple terms?

Why does John H. Day 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 John H. Day?

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 John H. Day.