astronomy

NGC 809

NGC 809 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 809 rather than just read about it. In short: NGC 809 is a lenticular galaxy located in the constellation Cetus about 245 million light-years (75 Mpc) away from the Milky Way. It was discovered by the American astronomer Lewis Swift in November 1886.

Key takeaways

NGC 809 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 809 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 809 from memory before moving on to harder problems.

Reference excerpt

NGC 809 is a lenticular galaxy located in the constellation Cetus about 245 million light-years (75 Mpc) away from the Milky Way. It was discovered by the American astronomer Lewis Swift in November 1886. The galaxy is receding from the Milky Way with a line of sight velocity component of 5,292 km/s. The morphological classification of NGC 809 is (R)S0+:, indicating an outer ring structure (R) around a lenticular galaxy (S0). The galaxy has a miniature central bar structure with weakly-developed spiral arms. There is a very red ring structure that is likely dust rich. This symmetrical ring was probably formed by the impact of a satellite on the central part of the galaxy.

Supernovae Two supernovae have been observed in NGC 809:

SN 2006ef (Type Ia, mag. 15.6) was discovered by the Lick Observatory Supernova Search (LOSS) on 18 August 2006. SN 2025yn (Type II, mag. 18.978) was discovered by ATLAS on 21 January 2025.

References

Illustrations

Worked examples

Example 1 — a first encounter with NGC 809

Start with the simplest possible case. Write down what NGC 809 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 809 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 809 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 809

In research: NGC 809 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 809 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 809 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Lenticular galaxies, Lenticular galaxy stubs, NGC objects, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 809 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 809 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 809 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 809 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 809 in simple terms?

Why does NGC 809 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 809?

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 809.