astronomy

Gliese 486 b

Gliese 486 b 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 486 b rather than just read about it. In short: Gliese 486 b, also named Su, is a rocky super-Earth exoplanet orbiting the red dwarf star Gliese 486 (Gar), 26.4 light-years away in the constellation Virgo. It is the only known planet in its system.

Key takeaways

Gliese 486 b 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 486 b to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Gliese 486 b from memory before moving on to harder problems.

Reference excerpt

Gliese 486 b, also named Su, is a rocky super-Earth exoplanet orbiting the red dwarf star Gliese 486 (Gar), 26.4 light-years away in the constellation Virgo. It is the only known planet in its system. It is very close to its star, completing an orbit in just 1.5 Earth days. Observations with the James Webb Space Telescope suggest that the planet likely has little to no atmosphere.

Discovery and naming Gliese 486 b was first detected in radial velocity observations by the CARMENES spectrograph, which observed its host star between 2016 and 2020. Observations by the TESS space telescope showed that the planet transits the star, allowing its size to be determined; combined with the mass measured by radial velocity, this indicated that it is a rocky planet. The MAROON-X spectrograph also contributed to the discovery, which was its first science result. The discovery was announced in March 2021 by a team of astronomers led by T. Trifonov and J. A. Caballero. The designation Gliese 486 b indicates the first planet discovered orbiting Gliese 486, as per exoplanet naming convention. This planet and its host star were included among the 20 systems selected to be named in the third NameExoWorlds campaign, beginning in August 2022. The approved names, announced in June 2023, were proposed by a team based in Spain that included Trifonov and Caballero. The planet is named Su and its host star is named Gar, after the Basque words for "fire" and "flame", in reference to the Basque saying "su eta gar" (fire and flame) which signifies passion and enthusiasm. As with other named exoplanets, astronomers have continued to use the original designation.

Characteristics

Gliese 486 b orbits very close to its star, at a distance of 0.017 AU (2.5 million km; 1.6 million mi) and an orbital period of 1.47 Earth days; for comparison, Mercury orbits at a distance of 0.387 AU (57.9 million km; 36.0 million mi) from the Sun with a period of 88 days. The orbit is nearly circular, with a very low eccentricity. The orbital inclination of 89.4° to the plane of the sky means the orbit is edge-on, allowing a transit to be observed. Gliese 486 b is classified as a super-Earth, with 2.77 times Earth's mass and 1.29 times its radius. This indicates a density of 6.66 g/cm3, consistent with a rocky, terrestrial planet. Due to its close orbit, the planet is very hot, with a measured temperature on the day side of around 865 K (592 °C; 1,097 °F).

Atmosphere Gliese 486 b is of interest as a rocky exoplanet suitable for atmospheric characterization with telescopes such as the James Webb Space Telescope (JWST). It can be used to constrain the position of the "cosmic shoreline", the theoretical boundary between planets with and without atmospheres. A ground-based 2022 study ruled out the presence of a cloudless hydrogen/helium-dominated atmosphere or a 100% water vapor atmosphere; a secondary planetary atmosphere with a higher molecular weight remained a possibility. Observations with JWST announced in 2023 detected signs of water vapor, but it was unclear if this was from the planet's atmosphere or from starspots on its host star. JWST observations of the planet's secondary eclipse published in 2024 found a planetary dayside temperature of 865±14 K (592 °C; 1,097 °F). This is consistent with a lack of heat redistribution, indicating that the planet likely has little to no atmosphere and the previous water vapor detection was likely a result of contamination from the host star. Gliese 486 b thus appears similar to other hot rocky planets around red dwarfs, such as LHS 3844 b (Kua'kua), GJ 1252 b, TRAPPIST-1b, Gliese 367 b (Tahay) and GJ 1132 b.

References

Further reading Sahu, Chandan K.; Majumdar, Liton; et al. (March 2025). "Unveiling the Interior Structure and Thermal Evolution of Super-Earth GJ 486b". The Astrophysical Journal. 981 (1): 80. arXiv:2501.09963. Bibcode:2025ApJ...981...80S. doi:10.3847/1538-4357/adabbe. Zhou, Junda; Huang, Zhenyang; et al. (May 2026). "Inversion of Hydrogen-rich Atmosphere and Water Content for GJ 486b". The Astrophysical Journal. 1002 (2): 541. arXiv:2604.11079. Bibcode:2026ApJ..1002..151Z. doi:10.3847/1538-4357/ae5e6c.

Illustrations

Worked examples

Example 1 — a first encounter with Gliese 486 b

Start with the simplest possible case. Write down what Gliese 486 b 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 486 b 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 486 b 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 486 b

In research: Gliese 486 b 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 486 b 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 486 b is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanets detected by radial velocity, Exoplanets discovered in 2021, Exoplanets in the Gliese Catalog, so understanding it makes those chapters shorter.
In everyday life: Look for Gliese 486 b 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 486 b in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Gliese 486 b 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 486 b out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Gliese 486 b in simple terms?

Why does Gliese 486 b 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 486 b?

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 486 b.