astronomy

NGC 718

NGC 718 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 718 rather than just read about it. In short: NGC 718 is an intermediate spiral galaxy in the constellation of Pisces. Its velocity with respect to the cosmic microwave background is 1,450±22 km/s, which corresponds to a Hubble distance of 69.7 ± 5.0 Mly (21.38 ± 1.54 Mpc).

Key takeaways

NGC 718 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 718 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 718 from memory before moving on to harder problems.

Reference excerpt

NGC 718 is an intermediate spiral galaxy in the constellation of Pisces. Its velocity with respect to the cosmic microwave background is 1,450±22 km/s, which corresponds to a Hubble distance of 69.7 ± 5.0 Mly (21.38 ± 1.54 Mpc). Additionally, one non-redshift measurement gives a similar distance of 69.80 Mly (21.400 Mpc). It was discovered by German-British astronomer William Herschel on 13 December 1784. NGC 718 has a possible active galactic nucleus, i.e. it has a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars. A star-forming disk has been detected around the core of NGC 718. The size of its semi-major axis is estimated at 1,100 ly (330 pc).

Supermassive black hole Based on measurements of the near-infrared K-band luminosity of the galaxy's bulge, NGC 718 has a supermassive black hole with a mass of 1×107.5M☉ (32 million solar masses).

NGC 676 group NGC 718 is a member of a small group of three galaxies known as the NGC 676 group. The other two galaxies are NGC 676 and NGC 693.

Intermediate-luminosity red transient One intermediate-luminosity red transient (ILRT) has been observed in NGC 718:

AT 2019udc (Type ILRT, mag. 18.813) was discovered by the Distance Less Than 40 Mpc Survey (DLT40) on 4 November 2019. This object had initially been classified as a luminous blue variable.

Illustrations

Worked examples

Example 1 — a first encounter with NGC 718

Start with the simplest possible case. Write down what NGC 718 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 718 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 718 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 718

In research: NGC 718 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 718 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 718 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1784, Discoveries by William Herschel, IRAS catalogue objects, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 718 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 718 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 718 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 718 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 718 in simple terms?

Why does NGC 718 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 718?

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 718.