astronomy

NGC 157

NGC 157 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 157 rather than just read about it. In short: NGC 157 is an intermediate spiral galaxy in the constellation of Cetus, positioned about 4° east of the star Iota Ceti. This galaxy can be viewed from suburban skies using a moderate-sized telescope.

Key takeaways

NGC 157 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 157 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 157 from memory before moving on to harder problems.

Reference excerpt

NGC 157 is an intermediate spiral galaxy in the constellation of Cetus, positioned about 4° east of the star Iota Ceti. This galaxy can be viewed from suburban skies using a moderate-sized telescope. It was discovered on December 13, 1783 by William Herschel. The compiler of the New General Catalogue, John Louis Emil Dreyer noted that NGC 157 was "pretty bright, large, extended, between 2 considerably bright stars". It is a relatively isolated galaxy; the nearest other galaxy of comparable luminosity lies at a separation of 4.2 Mly (1.3 Mpc).

The morphological classification of NGC 157 is SAB(rs)bc, indicating this is a weakly-barred spiral galaxy (SAB) with a transitional ring structure (rs) and moderate to loosely-wound arms (bc). The plane of the galaxy is inclined at an angle of 61.8° to the line of sight from the Earth. It has symmetric arms that become flocculent in the outer parts, breaking into multiple arms. The rotation curve for this galaxy undergoes a sharp decline, suggesting a low mass or a small dark matter halo. It is considered a quiescent galaxy, showing little star formation activity. However, there is a starburst region in the nucleus forming new stars at the rate of about one solar mass per year.

Supernovae This galaxy has been host to two observed supernova events.

SN 2009em (Type Ic, mag. 16.6) was discovered by Berto Monard on 5 May 2009, about 34″ west and 10″ south of the galaxy core. SN 2022jli (Type Ic, mag. 14.4) was discovered by Berto Monard on 5 May 2022.

References

External links Media related to NGC 157 at Wikimedia Commons

Illustrations

Worked examples

Example 1 — a first encounter with NGC 157

Start with the simplest possible case. Write down what NGC 157 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 157 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 157 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 157

In research: NGC 157 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 157 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 157 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1783, Cetus (constellation), Intermediate spiral galaxies, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 157 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 157 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 157 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 157 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 157 in simple terms?

Why does NGC 157 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 157?

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 157.