Gas giant · 55 Cnc

55 Cnc b

ExoplanetsDiscovered 1996

Scientific overview

55 Cnc b is a gas giant orbiting 55 Cnc, completing an orbit every 15 days, about 41 light-years from Earth. It was discovered in 1996 using the radial velocity method.

Host star

Copernicus

Spectral type

G8 V

Temperature

5,198 K

Mass

1.015 M☉

Planetary system — 55 Cnc system

View the 55 Cnc system (5 known planets).

Planet	Class	Radius (R⊕)	Period (d)	Distance (ly)
55 Cnc eRadial Velocity · 2004	Super-Earth	1.88	0.7365	41
55 Cnc bRadial Velocity · 1996	Gas giant	13.9	14.6516	41
55 Cnc cRadial Velocity · 2004	Gas giant	8.51	44.3936	41
55 Cnc fRadial Velocity · 2007	Gas giant	7.59	261	41
55 Cnc dRadial Velocity · 2002	Gas giant	13	4799	41

Discovery and detection

Detection method

Radial Velocity Method

Discovery year

1996

Knowledge connections

OrbitsCopernicus
Member of system55 Cnc system
Discovered by methodRadial Velocity Method
Catalogued inNASA Exoplanet Archive

Quick facts

Class: Gas giant
Host star: Copernicus
Discovery method: Radial Velocity Method
Discovery year: 1996
Orbital period: 14.6516 d
Semi-major axis: 0.118 AU
Eccentricity: 0.003
Radius: 13.9 R⊕
Mass: 263.98 M⊕
Density: 0.54 g/cm³ · derived
Equilibrium temp.: 700 K
Insolation: 45.63 S⊕
Distance: 41 ly

Density is derived from the archive mass and radius via ρ = M / (4⁄3·π·r³); all other values are catalogued measurements.

Derived values

Computed from source-backed inputs via standard formulae — not observations. Every input and constant is traced below.

Bulk density0.54 g/cm³derived
Formula & inputs
Formula: ρ = M / (4⁄3·π·r³) (v1.0.0, impl v1.0.0)
Inputs:
- massEarth = 263.98 M⊕ · NASA
- radiusEarth = 13.9 R⊕ · NASA
Assumptions: M⊕ = 5.972e+24 kg, R⊕ = 6371000 m (IAU 2015 B3 nominal); Assumes a uniform sphere.
Limitations: Withheld above 30 g/cm³ (inconsistent mass/radius inputs).; Archive mass/radius carry no propagated uncertainty here.
Uncertainty: not propagated (inputs carry no catalogued uncertainty)
Computed as of 2026-06-29.

Quality & authority

Partial

Unreviewed

Description: Complete
Source coverage: Partial
Relationship coverage: Complete
Review coverage: None
Citation coverage: None
Image coverage: Not applicable

Data from the NASA Exoplanet Archive. See source quality.