astronomy

Solar cycle 15

Solar cycle 15 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 Solar cycle 15 rather than just read about it. In short: Solar cycle 15 was the fifteenth solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 10.1 years, beginning in July 1913 and ending in August 1923.

Key takeaways

Solar cycle 15 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Solar cycle 15 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Solar cycle 15 from memory before moving on to harder problems.

Reference excerpt

Solar cycle 15 was the fifteenth solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 10.1 years, beginning in July 1913 and ending in August 1923. The maximum smoothed sunspot number observed during the solar cycle was 175.7 (August 1917), and the starting minimum was 2.5. During the minimum transit from solar cycle 15 to 16, there were a total of 534 days with no sunspots.

History Geomagnetic storms in March 1918, August 1919, October 1919, and March 1920 affected telegraph lines, while a solar flare on 13 May 1921 also affected rail signal and switching equipment, in what was known as the "New York Railroad Storm."

1921 A major geomagnetic storm during 13–15 May 1921 caused damage in communication systems and aurora displays in much of the eastern United States. In Sweden, the event caused major disruptions to the telephone exchange in Karlstad and in the early morning of May 15, the building burned down. Witnesses described the telephone cables going into the building as glowing.

Illustrations

Worked examples

Example 1 — a first encounter with Solar cycle 15

Start with the simplest possible case. Write down what Solar cycle 15 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 Solar cycle 15 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 Solar cycle 15 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 Solar cycle 15

In research: Solar cycle 15 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 Solar cycle 15 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: Solar cycle 15 is common in secondary-school and first-year university syllabi. It links to neighbouring topics Solar cycles, Sun stubs, so understanding it makes those chapters shorter.
In everyday life: Look for Solar cycle 15 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.

Affiliate

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

How to study Solar cycle 15 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Solar cycle 15 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 Solar cycle 15 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Solar cycle 15 in simple terms?

Solar cycle 15 was the fifteenth solar cycle since 1755, when extensive recording of solar sunspot activity began. The solar cycle lasted 10.1 years, beginning in July 1913 and ending in August 1923.

Why does Solar cycle 15 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 Solar cycle 15?

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 Solar cycle 15.