astronomy

NGC 918

NGC 918 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 918 rather than just read about it. In short: NGC 918 is a barred spiral galaxy in the constellation Aries, about 67 million light years from the Milky Way. It was discovered by John Herschel on Jan 11, 1831.

Key takeaways

NGC 918 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 918 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 918 from memory before moving on to harder problems.

Reference excerpt

NGC 918 is a barred spiral galaxy in the constellation Aries, about 67 million light years from the Milky Way. It was discovered by John Herschel on Jan 11, 1831. The brightness class of NGC 918 is III and it has a broad line of neutral hydrogen. NGC 918 is also an active nucleus galaxy (AGN). Moreover, it is a field galaxy which does not belong to a cluster or group and is therefore gravitationally isolated. Many non-redshift measures give a distance of 19,115 ± 6,160 Mpc (~62,3 million ly), which is within the distances calculated using the value shift.

Supernovae Two supernovae have been observed in NGC 918:

SN 2009js (Type II, mag. 17.2) was discovered by Kōichi Itagaki and independently by the Lick Observatory Supernova Search (LOSS) on October 11, 2009. This was the first subluminous supernova to be studied in infrared wavelengths. SN 2011ek (Type Ia, mag. 16.4) was discovered by Kōichi Itagaki on Aug. 4, 2011.

Illustrations

Worked examples

Example 1 — a first encounter with NGC 918

Start with the simplest possible case. Write down what NGC 918 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 918 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 918 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 918

In research: NGC 918 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 918 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 918 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aries (constellation), Astronomical objects discovered in 1831, Barred spiral galaxies, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 918 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 918 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 918 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 918 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 918 in simple terms?

NGC 918 is a barred spiral galaxy in the constellation Aries, about 67 million light years from the Milky Way. It was discovered by John Herschel on Jan 11, 1831.

Why does NGC 918 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 918?

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 918.