astronomy

Kepler-20e

Kepler-20e 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 Kepler-20e rather than just read about it. In short: Kepler-20e is an exoplanet orbiting Kepler-20. The planet is notable as it is the first planet with a smaller radius than Earth found orbiting a Sun-like star.

Key takeaways

Kepler-20e belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Kepler-20e to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Kepler-20e from memory before moving on to harder problems.

Reference excerpt

Kepler-20e is an exoplanet orbiting Kepler-20. The planet is notable as it is the first planet with a smaller radius than Earth found orbiting a Sun-like star. The planet is second-closest to the star after Kepler-20b, and at 1,040 K (770 °C; 1,410 °F), it is far too hot to have liquid water on its surface. Along with the other four planets in the system, Kepler-20e was announced on 20 December 2011. Kepler-20e is the first planet smaller than the Earth discovered to orbit a star other than the Sun. A year on Kepler-20e only lasts 6 days, as it is much closer to its host star than the Earth is to the Sun. The temperature at the surface of the planet, around 1400 degrees Fahrenheit, is much too hot to support life, as we know it. Kepler-20e is likely to be entirely rocky and without an atmosphere. The planet is tidally locked, always showing the same side to its host star, as the Moon to the Earth, and could have large temperature differences between its permanent night and day sides. Astronomers think that the planet is likely to be geologically active, due to its own formation process and the strong gravitational interactions with its host star. In this artistic depiction, the planet is represented with active volcanoes on both the night and day sides.

Orbit

With a semimajor axis of 0.0507 AUs, Kepler-20e's orbit has a period of 6.098 days (with an extremely small margin of error). The orbit has an inclination of 87.50°, making its transits observable from the Solar System. Like the other planets of the system, the planet has a high maximum eccentricity of 0.28, but the lowest in that system.

References

Illustrations

Worked examples

Example 1 — a first encounter with Kepler-20e

Start with the simplest possible case. Write down what Kepler-20e 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 Kepler-20e 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 Kepler-20e 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 Kepler-20e

In research: Kepler-20e 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 Kepler-20e 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: Kepler-20e is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanets discovered by the Kepler space telescope, Exoplanets discovered in 2011, Kepler-20, so understanding it makes those chapters shorter.
In everyday life: Look for Kepler-20e 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 Kepler-20e in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Kepler-20e 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 Kepler-20e out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Kepler-20e in simple terms?

Kepler-20e is an exoplanet orbiting Kepler-20. The planet is notable as it is the first planet with a smaller radius than Earth found orbiting a Sun-like star.

Why does Kepler-20e 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 Kepler-20e?

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 Kepler-20e.