science

Gullstrand (crater)

Gullstrand (crater) 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 Gullstrand (crater) rather than just read about it. In short: Gullstrand is a lunar impact crater that lies on the northern hemisphere on the Moon's far side. About one crater diameter to the southeast is the larger crater Perrine.

Key takeaways

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

Reference excerpt

Gullstrand is a lunar impact crater that lies on the northern hemisphere on the Moon's far side. About one crater diameter to the southeast is the larger crater Perrine. To the west-southwest is Quetelet. This crater has a circular rim that is relatively well-defined, and has only been moderately worn. A small, bell-shaped crater forms a break through the rim to the southwest, and a small craterlet is attached to the southeastern side along the rim of Gullstrand. An oddly shaped small crater feature is attached to the eastern edge. There are also tiny craters along the rim of Gullstrand along the northern and southern edges. The inner walls of Gullstrand are relatively simple and featureless, and the interior floor is not marked by any craters of note. There is a low central ridge at the midpoint. The crater was formally named by the IAU in 1970 after Swedish ophthalmologist Allvar Gullstrand. Gullstrand lies at the approximate margin of the Coulomb-Sarton Basin, a 530 km wide impact crater of Pre-Nectarian age.

Satellite craters By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Gullstrand.

References

Sources

Illustrations

Worked examples

Example 1 — a first encounter with Gullstrand (crater)

Start with the simplest possible case. Write down what Gullstrand (crater) 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 Gullstrand (crater) 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 Gullstrand (crater) 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 Gullstrand (crater)

In research: Gullstrand (crater) 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 Gullstrand (crater) 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: Gullstrand (crater) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Impact craters on the Moon, LQ02 quadrangle, so understanding it makes those chapters shorter.
In everyday life: Look for Gullstrand (crater) 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 Gullstrand (crater) in 20 minutes

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

Frequently asked questions

What is Gullstrand (crater) in simple terms?

Gullstrand is a lunar impact crater that lies on the northern hemisphere on the Moon's far side. About one crater diameter to the southeast is the larger crater Perrine.

Why does Gullstrand (crater) 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 Gullstrand (crater)?

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 Gullstrand (crater).