astronomy

Small Dark Spot

Small Dark Spot 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 Small Dark Spot rather than just read about it. In short: The Small Dark Spot, sometimes also called Dark Spot 2 or The Wizard's Eye, was an extraterrestrial vortex on the planet Neptune. It was the second largest southern cyclonic storm on the planet in 1989, when Voyager 2 flew by the planet.

Key takeaways

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

Reference excerpt

The Small Dark Spot, sometimes also called Dark Spot 2 or The Wizard's Eye, was an extraterrestrial vortex on the planet Neptune. It was the second largest southern cyclonic storm on the planet in 1989, when Voyager 2 flew by the planet. When the Hubble Space Telescope observed Neptune in 1994, the storm had disappeared.

Observation history The Small Dark Spot was discovered in 1989 by the Voyager 2 spacecraft along with the Great Dark Spot and Scooter (a bright fast moving cloud located between the two giant storms). The Small Dark Spot was found at a latitude of 54° South while rotating East around Neptune with a period of 16.1 hours. Unlike the Great Dark Spot (which has some of the highest measured wind speeds in the Solar System), wind speed data was not taken for the Small Dark Spot. The spot was also observed without any white "companion clouds" present around its edges, again in contrast to the Great Dark Spot. When NASA pointed the Hubble Space Telescope toward Neptune in 1994, both giant spots were no longer present.

Physical characteristics The nickname "Wizard's Eye" given to this storm comes from its distinct features which create a striking eye-like appearance. Overall the Small Dark Spot is significantly smaller but on the same order of magnitude as the Great Dark Spot and rotates about 30° further south and with a period about 2 hours shorter than the larger storm. The dark oval of this storm which created the overall outline for the eye-like shape was formed by a clockwise rotating vortex which sucked atmosphere inward toward the planet center. This action of pulling atmosphere downward created a hole in the upper methane cloud deck of Neptune and gave the storm its darker blue tone. Also present within the dark region of the storm were sharp band-lines potentially indicating unseen high winds, despite exact measurements having never been taken. The bright central region representing the pupil of the eye-like shape was formed by white methane-ice clouds upwelling from the center of the storm. Within the chaos of these central clouds are some larger structures, including a distinct V-shape on the East side of the storm indicating the storm's believed clockwise rotation. These clouds are composed of the same methane-ice that forms similar clouds called "companion clouds" present near the edges of other large storms on the planet; however, the Small Dark Spot did not have any of these companion clouds apparent in its 1989 observation. Additionally, no companion clouds were observed in the region of the spot in the 1994 observation of the planet.

Disappearance After being observed by Voyager 2 in 1989, the planet would not be observed in high resolution again until the Hubble Space Telescope turned its view to it in 1994. In 1994 and subsequent observations, both major storms had apparently vanished. The storm causing the Great Dark Spot, however, may have continued at a lower altitude as evidenced by the persistence of the storm's companion clouds. The Small Dark Spot did not have any companion clouds by which to judge survival of the storm causing the spot. While a conjectured mechanism for decay and death of large vortexes on Neptune is their approach to the equator where the planet has 400 meter per second jet streams, this storm (as well as others) could have also decayed from unexplained mechanisms of Neptune's atmosphere.

See also Dragon Storm (astronomy) Extraterrestrial cyclone Great Dark Spot Oval BA Great Red Spot Great White Spot

References

Illustrations

Worked examples

Example 1 — a first encounter with Small Dark Spot

Start with the simplest possible case. Write down what Small Dark Spot 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 Small Dark Spot 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 Small Dark Spot 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 Small Dark Spot

In research: Small Dark Spot 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 Small Dark Spot 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: Small Dark Spot is common in secondary-school and first-year university syllabi. It links to neighbouring topics 1989 in science, Neptune, Planetary spots, so understanding it makes those chapters shorter.
In everyday life: Look for Small Dark Spot 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 Small Dark Spot in 20 minutes

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

Frequently asked questions

What is Small Dark Spot in simple terms?

Why does Small Dark Spot 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 Small Dark Spot?

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 Small Dark Spot.