astronomy

Gliese 581b

Gliese 581b 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 581b rather than just read about it. In short: Gliese 581b or Gl 581b 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 first planet discovered of three confirmed in the system so far, and the second in order from the star.

Key takeaways

Gliese 581b 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 581b to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Gliese 581b from memory before moving on to harder problems.

Reference excerpt

Gliese 581b or Gl 581b 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 first planet discovered of three confirmed in the system so far, and the second in order from the star.

Discovery The planet was discovered by a team of French and Swiss astronomers, who announced their findings on November 30, 2005, as a discovery of one of the smallest exoplanets then found, with one conclusion being that planets may be more common around the smallest stars. It was the fifth planet found around a red dwarf star (after Gliese 876's first three planets and Gliese 436 b). The planet was discovered using the HARPS instrument, with which they found the host star to have a wobble that implied the existence of the planet. The astronomers published their results in Astronomy and Astrophysics Letters.

Orbit and mass Gliese 581b has a minimum mass of approximately 15.8 times the Earth's mass, similar to Neptune's mass. It does not transit its star, implying that its orbital inclination is less than 88.1 degrees. A 2024 study determined the inclination of the planet, allowing its true mass to be determined, which is about 30% greater than the minimum mass at about 20.5 Earth masses. The planet is rather close to Gliese 581 and completes a full orbit in only 5.37 days at a mean distance of about 6 million kilometers (0.04 AU). By comparison, Mercury is at a distance of 58 million kilometers (0.387 AU) and completes an orbit in 88 days.

Characteristics Gliese 581b is about 0.04 AU from its sun. It is likely close to Gliese 436 b in mass, temperature, and (with Gliese 876 d) susceptibility to solar effects such as coronal mass ejection. Gliese 581b does not transit. At the least, given that Gliese 581b orbits alongside two other planets (Gliese 581c and e) and that Gliese 436 b (thus far) stands alone, their formation must have differed.

See also Habitability of red dwarf systems

Notes

References

External links

ESO: The Dwarf that Carries a World SolStation: Gliese 581 / HO Librae Archived 2008-10-10 at the Wayback Machine

Illustrations

Worked examples

Example 1 — a first encounter with Gliese 581b

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

In research: Gliese 581b 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 581b 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 581b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanets detected by radial velocity, Exoplanets discovered in 2005, Exoplanets in the Gliese Catalog, so understanding it makes those chapters shorter.
In everyday life: Look for Gliese 581b 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 581b in 20 minutes

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

Frequently asked questions

What is Gliese 581b in simple terms?

Why does Gliese 581b 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 581b?

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 581b.