astronomy

Gliese 581e

Gliese 581e 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 Gliese 581e rather than just read about it. In short: Gliese 581e or Gl 581e is an exoplanet orbiting within the Gliese 581 system, located 20.5 light-years (6.3 parsecs) away from Earth in the Libra constellation. It is the third planet discovered in the system (fourth if the disputed planet candidate Gliese 581d is included) and the first in order from the star.

Key takeaways

Gliese 581e belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Gliese 581e to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Gliese 581e from memory before moving on to harder problems.

Reference excerpt

Gliese 581e or Gl 581e is an exoplanet orbiting within the Gliese 581 system, located 20.5 light-years (6.3 parsecs) away from Earth in the Libra constellation. It is the third planet discovered in the system (fourth if the disputed planet candidate Gliese 581d is included) and the first in order from the star.

Discovery The planet was discovered by an Observatory of Geneva team led by Michel Mayor, using the HARPS instrument on the European Southern Observatory 3.6 m (140 in) telescope in La Silla, Chile. The discovery was announced on 21 April 2009. Mayor's team employed the radial velocity technique, in which the orbit size and mass of a planet are determined based on the small perturbations it induces in its parent star's orbit via gravity.

Characteristics With a minimum mass of about 1.9 Earth masses, Gliese 581e was the least massive exoplanet known around a normal star at the time of discovery in 2009, with only PSR B1257+12 A being less massive. A 2024 study determined the orbital inclination of the planet, allowing its true mass to be determined, which is about 30% greater than the minimum mass at about 2.5 Earth masses. Gliese 581e completes an orbit around its parent star in 3.15 days. At an orbital distance of just 0.028 AU (4,200,000 km) from its parent star, it orbits further in than the habitable zone. Although scientists think it probably has a rocky surface similar to Earth, it is also likely to experience intense tidal heating similar to (and likely more intense than) that affecting Jupiter's moon Io.

See also Habitability of red dwarf systems

Notes

References

External links Media related to Gliese 581 e at Wikimedia Commons Discovery of smallest exoplanet yields 'extraordinary' find at Wikinews

Lightest exoplanet yet discovered European Southern Observatory press release Scientists discover a nearly Earth-sized planet Archived 2009-04-29 at the Wayback Machine Publications at Exoplanet.eu Archived 2011-06-02 at the Wayback Machine

Illustrations

Worked examples

Example 1 — a first encounter with Gliese 581e

Start with the simplest possible case. Write down what Gliese 581e 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 Gliese 581e 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 Gliese 581e 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 Gliese 581e

In research: Gliese 581e 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 Gliese 581e 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: Gliese 581e is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanets detected by radial velocity, Exoplanets discovered in 2009, Exoplanets in the Gliese Catalog, so understanding it makes those chapters shorter.
In everyday life: Look for Gliese 581e 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 Gliese 581e in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Gliese 581e 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 Gliese 581e out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Gliese 581e in simple terms?

Why does Gliese 581e 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 Gliese 581e?

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 Gliese 581e.