51 Eri b
ILLUSTRATION FROM EQUILIBRIUM TEMPERATURE 807 K · HOST STAR 7420 K
OVERVIEW
] EXOPLANET51 Eri b is a in the constellation Eridanus, 97.06 from Earth. It orbits 51 Eri at a mean distance of 10.4 . Its mass is 10.90 . It was discovered in 2015.
- WHAT IT IS
- Gas giant
- HOW FAR
- 97.06
- ONE ORBIT TAKES
- 24.9
The light arriving now left it that long ago.
One trip round 51 Eri.
OBSERVING
] FROM WHERE YOU AREWhat it takes to see 51 Eri 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 51 Eri 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
- 20.5
- PROPER MOTION SINCE
- none published
Computed for 2026-08-27 00:00 UT. No proper motion is published for 51 Eri 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
- 807
- Host star spectral type
- Host star temperature
- 7422 ±58
- Host star mass
- 1.75 ±0.05
- Host star radius
- 1.45 ±0.02
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
- 51 Eri
- Orbital period
- 24.91 +1100 / −1500
- Eccentricity
- +0.08 / −0.06
- Inclination
- 141 +9 / −7
- Argument of periastron
- 82 ±23
- Periastron epoch
- 2461699.0000
- Stars in system
- 3
- Planets in system
- 1
WHEN IT WAS FOUND
Who first saw it, from where, and by what method.
- Discovery method
- Imaging
- Discovered at
- Gemini Observatory
ALSO KNOWN AS
] 2 DESIGNATIONS- Exoplanet 51 Eri b
- Host star 51 Eri
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 Archive51 Eri b
Every published parameter set for this planet side by side, with the paper each one came from.
- SIMBAD51 Eri
Cross-identifications, measured values and the reference behind each of them. Keyed on the host star.
- ADSobject:"51 Eri"
Papers indexed against this object rather than against the string, newest first. Keyed on the host star.
- VizieR5″ around 69.4007 -2.4738
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. 51 Eri b [catalogue entry]. Data release DR1 (2026-08-21). https://spacecatalog.org/object/51-eri-b
@misc{spacecatalog_51-eri-b,
author = {{SpaceCatalog}},
title = {{51 Eri b}},
howpublished = {SpaceCatalog, data release DR1 (2026-08-21)},
year = {2026},
url = {https://spacecatalog.org/object/51-eri-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.