astronomy

NGC 18

NGC 18 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 NGC 18 rather than just read about it. In short: NGC 18 is a double star system located in the constellation of Pegasus. It was first recorded by Herman Schultz on 15 October 1866.

Key takeaways

NGC 18 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect NGC 18 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 18 from memory before moving on to harder problems.

Reference excerpt

NGC 18 is a double star system located in the constellation of Pegasus. It was first recorded by Herman Schultz on 15 October 1866. It was looked for but not found by Édouard Stephan on 2 October 1882. It was independently observed by Guillaume Bigourdan in November 1886. Both stars are 2528±20 light-years away, and based on this distance have a minimum separation of approximately 2,700 astronomical units, an unusually wide separation for a binary system.

See also Double star Binary star List of NGC objects List of NGC objects (1–1000)

References

External links Media related to NGC 18 at Wikimedia Commons

Illustrations

Worked examples

Example 1 — a first encounter with NGC 18

Start with the simplest possible case. Write down what NGC 18 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 NGC 18 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 NGC 18 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 NGC 18

In research: NGC 18 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 NGC 18 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: NGC 18 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1866, Double stars, Multiple star stubs, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 18 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 NGC 18 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 18 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 NGC 18 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 18 in simple terms?

NGC 18 is a double star system located in the constellation of Pegasus. It was first recorded by Herman Schultz on 15 October 1866.

Why does NGC 18 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 NGC 18?

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 NGC 18.