astronomy

S/2018 J 4

S/2018 J 4 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 S/2018 J 4 rather than just read about it. In short: S/2018 J 4 is a small outer natural satellite of Jupiter discovered by Scott S. Sheppard on 11 May 2018, using the 4.0-meter Víctor M.

Key takeaways

S/2018 J 4 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect S/2018 J 4 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of S/2018 J 4 from memory before moving on to harder problems.

Reference excerpt

S/2018 J 4 is a small outer natural satellite of Jupiter discovered by Scott S. Sheppard on 11 May 2018, using the 4.0-meter Víctor M. Blanco Telescope at Cerro Tololo Observatory, Chile. It was announced by the Minor Planet Center on 20 January 2023, after observations were collected over a long enough time span to confirm the satellite's orbit. The satellite has a diameter of about 2 km (1.2 mi) for an absolute magnitude of 16.7. S/2018 J 4 is an irregular moon of Jupiter on a highly inclined prograde orbit at an angle of 53° with respect to the ecliptic plane. It belongs to the same group as the similarly inclined moon Carpo, which was long thought to be an outlier until the discovery of S/2018 J 4. Like all irregular moons of Jupiter, S/2018 J 4's orbit is highly variable over time due to gravitational perturbations by the Sun and other planets. On average, S/2018 J 4's orbit has a semi-major axis of 16.3 million km (10.1 million mi), an eccentricity of 0.18, and a very high inclination of 50° with respect to the ecliptic. Like Carpo, S/2018 J 4's very high inclination subjects it to the Lidov–Kozai resonance, where there is a periodic exchange between its orbital eccentricity and inclination while its argument of pericenter oscillates about a constant value without apsidally precessing. For example, the Lidov–Kozai resonance causes Carpo's eccentricity and inclination to fluctuate between 0.19–0.69 and 44–59°, respectively. S/2018 J 4's argument of pericenter oscillates about 270° with respect to the ecliptic.

References

Illustrations

Worked examples

Example 1 — a first encounter with S/2018 J 4

Start with the simplest possible case. Write down what S/2018 J 4 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 S/2018 J 4 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 S/2018 J 4 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 S/2018 J 4

In research: S/2018 J 4 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 S/2018 J 4 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: S/2018 J 4 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 2018, Carpo group, Discoveries by Scott S. Sheppard, so understanding it makes those chapters shorter.
In everyday life: Look for S/2018 J 4 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.

Ask Teacher Smith questions about this articleOpens your AI tutor with a question about “S/2018 J 4” →

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study S/2018 J 4 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what S/2018 J 4 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 S/2018 J 4 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is S/2018 J 4 in simple terms?

S/2018 J 4 is a small outer natural satellite of Jupiter discovered by Scott S. Sheppard on 11 May 2018, using the 4.0-meter Víctor M.

Why does S/2018 J 4 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 S/2018 J 4?

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 S/2018 J 4.