astronomy

NGC 1218

NGC 1218 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 1218 rather than just read about it. In short: NGC 1218 is a lenticular galaxy in Cetus that hosts the radio source 3C 78. It was discovered in 1886 by American astronomer Lewis A.

Key takeaways

NGC 1218 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 1218 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of NGC 1218 from memory before moving on to harder problems.

Reference excerpt

NGC 1218 is a lenticular galaxy in Cetus that hosts the radio source 3C 78. It was discovered in 1886 by American astronomer Lewis A. Swift. It is located at l = 174.86, b = -44.51 in the galactic coordinate system.

History Discovered by Lewis Swift on September 6, 1886, NGC 1218 was one of the original objects included in the New General Catalogue. 3C 78 was discovered c. 1957, and subsequently included in the Third Cambridge Catalogue of Radio Sources (3C). In 1982, it was found that the nucleus of NGC 1218 emits a radio jet. A follow-up study in 1986 corroborated the presence of the jet, as well as finding evidence of a possible weak counter-jet. The Hubble Space Telescope observed NGC 1218 on August 17, 1994. An optical jet of synchrotron radiation similar to that of Messier 87 was subsequently found. On September 6, 2000, a type Ia supernova was detected in NGC 1218. A 2002 study found that the previously identified radio jet was the cause. In 2023, the proper motion of 3C 78 was determined using observations from the Very Large Array (VLA), as well as a single observation from the Atacama Large Millimeter/submillimeter Array (ALMA).

Composition and structure NGC 1218 is a lenticular (S/0a) radio galaxy, with a radio halo roughly equivalent in size to the optical halo's extent. The observable synchrotron jet has a total length of 1.37 arcseconds (0.75 kpc), and expands substantially at 0.5 arcseconds from the nucleus. NGC 1218 has an approximate hydrogen mass of <36×109 M☉.

3C 78 3C 78 is an astronomical radio source with an angular extent of approximately 80 × 55 arcseconds squared. According to Tabara and Inoue (1980), 3C 78 has a rotation measure of 8.7 ± 1.9 m−2 and an intrinsic position angle of 87° ± 4°, although Simard-Normandin, Kronberg, and Button (1981) claim that it has a rotation measure of 14 ± 2 m−2 and an intrinsic position angle of 85° ± 3°. It possesses a radio jet approximately one arcsecond (0.58 kpc) in length, with three bright, compact inhomogeneities (or "knots"), with the second and thirds ones being the most prominent. The second knot has a longitudinal motion of approximately 0.51 ± 0.14c at roughly 200 pc, and the third knot had an apparent superluminal backwards motion of −2.6 ± 2c prior to 2000, followed by a forward motion of 0.5 ± 2c, both at roughly 300 pc.

Notes

References

External links SIMBAD listing NED listing VizieR listing (VizieR also has listings for alternate identifiers)

Illustrations

Worked examples

Example 1 — a first encounter with NGC 1218

Start with the simplest possible case. Write down what NGC 1218 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 1218 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 1218 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 1218

In research: NGC 1218 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 1218 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 1218 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 3C objects, Cetus (constellation), Discoveries by Lewis Swift, so understanding it makes those chapters shorter.
In everyday life: Look for NGC 1218 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 1218 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what NGC 1218 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 1218 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is NGC 1218 in simple terms?

NGC 1218 is a lenticular galaxy in Cetus that hosts the radio source 3C 78. It was discovered in 1886 by American astronomer Lewis A.

Why does NGC 1218 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 1218?

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 1218.