astronomy

John E. Bortle

John E. Bortle 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 John E. Bortle rather than just read about it. In short: John E. Bortle is an American amateur astronomer.

Key takeaways

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

Reference excerpt

John E. Bortle is an American amateur astronomer. He is best known for creating the Bortle scale to quantify the darkness of the night sky. Bortle has made a special study of comets. He has recorded thousands of observations relating to more than 300 comets. From 1977 until 1994 he authored the monthly '"Comet Digest" in Sky and Telescope magazine. He also had a special interest in variable stars. After joining the AAVSO in 1963, Bortle contributed more than 215,000 visual observations to the AAVSO's database before retiring from the organization in 2020.. From 1970 until 2000 he edited the monthly AAVSO circular for the American Association of Variable Star Observers. He published his darkness scale in Sky and Telescope magazine in 2001. The scale ranges from 1 (extremely dark rural area or national park, usually at high elevation, low humidity, and low wind) to 9 (urban inner city). Today that scale is widely used throughout the world by the amateur astronomy community for ascertaining and relating their sky conditions to colleagues. John Bortle created a predictive model to calculate if a comet would survive perihelion or not, known as the Bortle survival limit. According to it, if the comet is brighter than H10 = 7.0 + 6q, where H10 is the absolute magnitude of the comet and q the perihelion distance in astronomical units, it was likely to survive.

Recognition Astronomical Society of the Pacific's Comet Medal (1974) for significant contributions to the research of comets. American Association of Variable Star Observers 23rd Merit Award (1983), for his editorship of the AAVSO Circular and observing record. E.E.Barnard Observers Award of the Western Amateur Astronomers (1990), for his observational work on comets. The asteroid 4673 Bortle was named in his honor by the International Astronomical Union. Walter Scott Houston Award of the Northeast Region of the Astronomical League (2010). Leslie Peltier Award from the Astronomical League (2013).

References

Worked examples

Example 1 — a first encounter with John E. Bortle

Start with the simplest possible case. Write down what John E. Bortle 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 John E. Bortle 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 John E. Bortle 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 John E. Bortle

In research: John E. Bortle 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 John E. Bortle 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: John E. Bortle is common in secondary-school and first-year university syllabi. It links to neighbouring topics Amateur astronomers, American astronomers, Living people, so understanding it makes those chapters shorter.
In everyday life: Look for John E. Bortle 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 John E. Bortle in 20 minutes

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

Frequently asked questions

What is John E. Bortle in simple terms?

John E. Bortle is an American amateur astronomer.

Why does John E. Bortle 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 John E. Bortle?

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 John E. Bortle.