Proxima Cen b

EXOPLANETTerrestrial planet

ILLUSTRATION FROM EQUILIBRIUM TEMPERATURE 218 K · RADIUS 1.02 EARTH RADII · HOST STAR 2900 K

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OVERVIEW

] EXOPLANET

Proxima Cen b is a terrestrial planet in the constellation Centaurus, 4.244 from Earth. It orbits Proxima Cen at a mean distance of 0.04848 . It has a mass of 1.06 and a radius of 1.02 · 6506 . It was discovered in 2016.

The closest exoplanet to Earth, orbiting the nearest star in its — though its sun's frequent flares may have long since stripped any atmosphere.

WHAT IT IS: Terrestrial planet
HOW FAR: 4.244
HOW BIG: 1.02 · 6506
WHERE TO LOOK: Centaurus
ONE ORBIT TAKES: 11.2

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THE MODEL

] CATALOGUED RADIUS

DRAG TO ORBIT

CALCULATED · NOT AN OBSERVATION · CATALOGUED RADIUS · EQUILIBRIUM TEMPERATURE 218 K · RADIUS 1.02 EARTH RADII · HOST STAR 2900 K

Drawn from the catalogued radius and from the same properties the picture at the top of this page uses, at the distance a flight to it would stop. Drag it, or use the arrow keys, to look from another direction. The stars behind are the 498,631 this catalogue holds real distances for, at their real positions and drawn from where the camera actually is — so the constellations are wrong, and that is the point. This is the sky from there, not the sky from here.

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OBSERVING

] FROM WHERE YOU ARE

What it takes to see Proxima Cen b for yourself. Everything in this part of the page is worked out for a real horizon, a real night and the equipment you say you have.

TONIGHT

Say where you are, and this line says when Proxima Cen b is worth going out for.

VIEW IN SKY MAP FLY TO PROXIMA CEN B

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APPARENT PLACE

] EQUINOX J2026.8

Where a telescope has to be pointed today, which is not quite where the catalogue records the object: the coordinate grid itself has turned since the year 2000 the catalogue is referred to.

RIGHT ASCENSION
DECLINATION
GRID TURNED SINCE: 16.0
PROPER MOTION SINCE: none published

Computed for 2026-10-11 00:00 UT. No proper motion is published for Proxima Cen b, so nothing here moves the object; what separates this from the catalogued position above is the coordinate grid turning under it — about fifty arcseconds a year of precession since 2000, and the small nodding of the Earth’s axis on top of that. The catalogue it came from publishes no error for that position, so nothing here says how far this arithmetic can be trusted — the digits above are as precise as the place they were computed from, and no more. Aberration, parallax and refraction are left out. Aberration swings every position by up to twenty arcseconds over a year; parallax stays under an arcsecond for all but the nearest stars; refraction is nothing overhead and about half a degree at the horizon, where it answers to the air, not the sky. The same figure for any date.

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CATALOG DATA

] 16 FIELDS

The raw catalogue values, as the source published them, with the error bars where one was published — sorted by what each set of figures is about rather than by the order they happened to be stored in.

WHAT KIND OF THING IT IS

What the object is in itself, rather than how it happens to look from here.

Equilibrium temperature: 218
Host star spectral type
Host star temperature: 2900 ±100
Host star mass: 0.1221 ±0.0022
Host star radius: 0.141 ±0.021

HOW BRIGHT IT IS

What the light adds up to, measured through one filter at a time. A magnitude is a brightness on a backwards scale — the smaller the number, the brighter the object.

Host star apparent magnitude ()

THE ORBIT

The shape of the path, where the object sits on it, and the instant those figures were true of. An orbit is a fit to observations and drifts away from the real one either side of its epoch.

Host star: Proxima Cen
Orbital period: 11.18465 ±0.00053
Eccentricity
Argument of periastron: 3.3 +1.8 / −2.3
Periastron epoch: 2460548.5900
midpoint: 2457897.9000
Stars in system: 3
Planets in system: 2

WHEN IT WAS FOUND

Who first saw it, from where, and by what method.

Discovery method
Discovered at: European Southern Observatory

[

ALSO KNOWN AS

] 1 DESIGNATIONS

Exoplanet Proxima Cen b

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LOOK IT UP ELSEWHERE

] 4 SERVICES

Each link carries the identifier printed beside it. Nothing on this page is a measurement of our own, so a number that disagrees with one of these is worth reporting — and a service that has never catalogued this object under this name will say so plainly.

NASA Exoplanet ArchiveProxima Cen b
Every published parameter set for this planet side by side, with the paper each one came from.
SIMBADProxima Cen
Cross-identifications, measured values and the reference behind each of them. Keyed on the host star.
ADSobject:"Proxima Cen"
Papers indexed against this object rather than against the string, newest first. Keyed on the host star.
VizieR5″ around 217.3935 -62.6762
Every published table with a row at this position, searched by coordinates rather than by name.

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CITE THIS PAGE

] DR1

This page is live and its numbers move when an upstream refreshes, so the citation names the release the rows belong to rather than the day you read them. The release itself is frozen, republished as a bundle, and is what a data-availability statement should point at.

PLAIN TEXT

SpaceCatalog. Proxima Cen b [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/proxima-cen-b

BIBTEX

@misc{spacecatalog_proxima-cen-b,
  author       = {{SpaceCatalog}},
  title        = {{Proxima Cen b}},
  howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},
  year         = {2026},
  url          = {https://spacecatalog.org/object/proxima-cen-b},
  note         = {Catalogue entry, data release DR1 (2026-08-21). Values from NASA Exoplanet Archive (Planetary Systems Composite Parameters).}
}

The values above were taken from NASA Exoplanet Archive (Planetary Systems Composite Parameters) — No licence stated; acknowledgement requested. Citing this page does not replace citing that catalogue.

That catalogue asks for this acknowledgement: This research has made use of the NASA Exoplanet Archive, which is operated by the California Institute of Technology, under contract with the National Aeronautics and Space Administration under the Exoplanet Exploration Program. Cite Christiansen et al. (2025), Planetary Science Journal (doi:10.3847/PSJ/ade3c2), and the literature reference given with each value.

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