astronomy

Proxima Centauri c

Proxima Centauri c 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 Proxima Centauri c rather than just read about it. In short: Proxima Centauri c (also called Proxima c or Alpha Centauri Cc) is a disputed exoplanet candidate, proposed to be orbiting the red dwarf star Proxima Centauri, which is the closest star to the Sun and part of a triple star system. It is located approximately 4.2 light-years (1.3 parsecs; 40 trillion kilometres; 25 trillion miles) from Earth in the constellation of Centaurus.

Key takeaways

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

Reference excerpt

Proxima Centauri c (also called Proxima c or Alpha Centauri Cc) is a disputed exoplanet candidate, proposed to be orbiting the red dwarf star Proxima Centauri, which is the closest star to the Sun and part of a triple star system. It is located approximately 4.2 light-years (1.3 parsecs; 40 trillion kilometres; 25 trillion miles) from Earth in the constellation of Centaurus. If Proxima c exists, this would make it, along with Proxima b and Proxima d, the closest known exoplanets to the Solar System.

Characteristics As originally proposed, Proxima Centauri c would be a super-Earth or mini-Neptune about 7 times as massive as Earth, orbiting at roughly 1.49 AU (223 million km; 139 million mi) every 1,928 days (5.28 years). Due to its large mass and its distance from Proxima Centauri, the exoplanet would be uninhabitable and too cold for liquid water to exist on the surface, with an equilibrium temperature of approximately 39 K (−234.2 °C; −389.5 °F). According to a 2025 study, the originally proposed planet most likely does not exist, but there may be a smaller planet with a similar orbit. The planet does not transit its parent star from the point of view of an Earth-based observer.

Discovery The planet candidate was first reported by Italian astrophysicist Mario Damasso and his colleagues in April 2019. Damasso's team had noticed minor movements of Proxima Centauri in the radial velocity data from the ESO's HARPS instrument, analyzed earlier by Ukrainian astrophysicist Yakiv Pavlenko and his colleagues at the Instituto de Astrofísica de Canarias, indicating a possible second planet orbiting Proxima Centauri. The discovery was published on 15 January 2020. Subsequent studies in 2020 also found evidence for Proxima c via astrometry, including Hubble data from c. 1995, allowing its inclination and true mass to be determined. Also in June 2020, a possible directly imaged counterpart of Proxima c was detected in the infrared with SPHERE, but the authors admit that they "did not obtain a clear detection". If their candidate source is in fact Proxima Centauri c, it is too bright for a planet of its mass and age, implying that the planet may have a ring system with a radius of around 5 RJ. At the time, the multiple lines of evidence appeared to confirm the planet. However, a 2022 study questioned the planetary nature of the observed radial velocity signal corresponding to Proxima c, whose detection could not be recreated, attributing it to systematic effects. As of 2025, evidence for Proxima c remains inconclusive; observations with the NIRPS spectrograph were unable to confirm it, but found hints of a lower-amplitude signal, different from the originally proposed planet, with a similar period. Another 2025 study, reanalyzing Hubble and Gaia astrometry, estimated a mass of 3.4+5.2−3.4 M🜨 for Proxima c, assuming a circular, face-on orbit. This is broadly consistent with previous estimates, but also consistent with a non-detection.

Notes

References

Illustrations

Worked examples

Example 1 — a first encounter with Proxima Centauri c

Start with the simplest possible case. Write down what Proxima Centauri c 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 Proxima Centauri c 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 Proxima Centauri c 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 Proxima Centauri c

In research: Proxima Centauri c 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 Proxima Centauri c 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: Proxima Centauri c is common in secondary-school and first-year university syllabi. It links to neighbouring topics Exoplanet candidates, Exoplanets detected by astrometry, Exoplanets detected by radial velocity, so understanding it makes those chapters shorter.
In everyday life: Look for Proxima Centauri c 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 Proxima Centauri c in 20 minutes

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

Frequently asked questions

What is Proxima Centauri c in simple terms?

Why does Proxima Centauri c 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 Proxima Centauri c?

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 Proxima Centauri c.