Proxima Cen b
ILLUSTRATION FROM EQUILIBRIUM TEMPERATURE 218 K · RADIUS 1.02 EARTH RADII · HOST STAR 2900 K
OVERVIEW
] EXOPLANETProxima 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 habitable zone — 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
- ONE ORBIT TAKES
- 11.2
The light arriving now left it that long ago.
Its radius: half the width across.
One trip round Proxima Cen.
THE MODEL
] CATALOGUED RADIUSCALCULATED · 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.
OBSERVING
] FROM WHERE YOU AREWhat 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.
Say where you are, and this line says when Proxima Cen b is worth going out for.
APPARENT PLACE
] EQUINOX J2026.7Where 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
- 15.9
- PROPER MOTION SINCE
- none published
Computed for 2026-08-27 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. Aberration and refraction are not included, and neither is parallax; each is under an arcminute, which is also about as well as the catalogued position is known. The same figure for any date.
CATALOG DATA
] 16 FIELDSThe 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 IT IS MADE OF
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
- Transit 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
- Radial Velocity
- Discovered at
- European Southern Observatory
ALSO KNOWN AS
] 1 DESIGNATIONS- Exoplanet Proxima Cen b
LOOK IT UP ELSEWHERE
] 4 SERVICESEach 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.
CITE THIS PAGE
] DR1This 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.
SpaceCatalog. Proxima Cen b [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/proxima-cen-b
@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) — Public domain (NASA). Citing this page does not replace citing that catalogue.
RECENT ACTIVITY
] 3 ITEMS- RedDots: Multiplanet system around M dwarf GJ 887 in the solar neighborhood2026-02-09 · arXiv · PAPER · C. Hartogh, S. V. Jeffers, S. Dreizler, J. R. Barnes, C. A. Haswell, F. Liebing
- The Phase Induced Amplitude Apodizer and Nuller -- High transmission, high dispersion coronagraphy at 2λ/D2025-03-24 · arXiv · PAPER · N. Blind, N. Restori, B . Chazelas, C. Lovis, J. Kühn, C. Mordasini
- Magnetized winds of M-type stars and star-planet magnetic interactions: uncertainties and modeling strategy2024-10-02 · arXiv · PAPER · Victor Réville, Jamie M. Jasinski, Marco Velli, Antoine Strugarek, Allan Sacha Brun, Neil Murphy
arXiv · UPDATED DAILY