astronomy

Stephano (moon)

Stephano (moon) 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 Stephano (moon) rather than just read about it. In short: Stephano, also known as Uranus XX and previously as S/1999 U 2, is an irregular moon of Uranus. It was discovered on 18 July 1999 by Brett J.

Key takeaways

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

Reference excerpt

Stephano, also known as Uranus XX and previously as S/1999 U 2, is an irregular moon of Uranus. It was discovered on 18 July 1999 by Brett J. Gladman et al. and it was named after the drunken butler in William Shakespeare's play The Tempest. Stephano orbits Uranus at an average distance of about 8 million km (5.0 million mi) and takes about 677 Earth days (1.8 Earth years) to complete one orbit. It is a member of the Caliban group, the first identified group of irregular Uranian moons that share similar orbital characteristics. Stephano is estimated to have a diameter of 32 km (20 mi), though most of its physical properties are unknown.

Discovery and naming Stephano was discovered on 18 July 1999, together with Prospero and Setebos, by Brett J. Gladman et al.

When the discovery of Stephano was announced, it was given the temporary provisional designation S/1999 U 2 by the Minor Planet Center. It was later named and given the Roman numeral designation Uranus XX by the International Astronomical Union's Working Group for Planetary System Nomenclature on 21 August 2000. The moon was named after the drunken butler in William Shakespeare's play The Tempest.

Orbit

Stephano orbits Uranus at a mean distance of approximately 8 million km and completes one revolution in about 677 days. Its orbit is retrograde, moderately inclined with an inclination of approximately 144° and eccentricity of 0.200. Its orbital elements are subject to continuous variations caused by solar and planetary perturbations. It is a member of the Caliban group, which orbits Uranus at orbital distances between 7–8 million km (4,3–4.9 million mi) and inclinations between 141–144°.

Physical characteristics Very little is known about its physical properties. Assuming Stephano has a low albedo of 0.04 like other Uranian irregular moons, its brightness suggests a diameter of about 32 km (20 mi). Stephano appears reddish in visible light (colour indices B–V = 0.97 ± 0.07, V–R = 0.66 ± 0.05 and is nearly as red as many trans-Neptunian objects. It may even be redder than Caliban and Sycorax; however, additional observations are required to confirm this.

Origin Stephano probably did not form near Uranus but was captured by Uranus later. It is a member of the Caliban group, whose members—including Stephano—are thought to be fragments of an earlier parent body that was shattered in a collision, making them a collisional family.

Exploration Stephano has not been imaged up close by a space probe. All Uranian irregular moons including Stephano are planned to be distant observation targets for the proposed Uranus Orbiter and Probe (UOP), which will measure the Uranian irregular moons' rotation periods and shapes by watching their brightness change over time. The UOP may not be able to do a close flyby of Stephano because the moon does not orbit near the ecliptic plane.

See also Moons of Uranus Other Uranian irregular moons discovered in 1999: Prospero Setebos Irregular satellites

References

Sheppard, S. S.; Jewitt, D.; Kleyna, J. (2005). "An Ultradeep Survey for Irregular Satellites of Uranus: Limits to Completeness". The Astronomical Journal. 129 (1): 518–525. arXiv:astro-ph/0410059. Bibcode:2005AJ....129..518S. doi:10.1086/426329. S2CID 18688556.

External links Stephano Profile by NASA's Solar System Exploration David Jewitt pages Uranus' Known Satellites (by Scott S. Sheppard) MPC: Natural Satellites Ephemeris Service

Illustrations

Stephano (moon): Animation of discovery images taken by the CFHT in July 1999 — Animation of discovery images taken by the CFHT in July 1999

Worked examples

Example 1 — a first encounter with Stephano (moon)

Start with the simplest possible case. Write down what Stephano (moon) 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 Stephano (moon) 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 Stephano (moon) 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 Stephano (moon)

In research: Stephano (moon) 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 Stephano (moon) 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: Stephano (moon) is common in secondary-school and first-year university syllabi. It links to neighbouring topics Astronomical objects discovered in 1999, Caliban group, Discoveries by Brett J. Gladman, so understanding it makes those chapters shorter.
In everyday life: Look for Stephano (moon) 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 Stephano (moon) in 20 minutes

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

Frequently asked questions

What is Stephano (moon) in simple terms?

Stephano, also known as Uranus XX and previously as S/1999 U 2, is an irregular moon of Uranus. It was discovered on 18 July 1999 by Brett J.

Why does Stephano (moon) 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 Stephano (moon)?

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 Stephano (moon).