Key parameters at a glance

A radius of 3.05 Earth radii
A mass of 2.07 Earth masses
Surface gravity around 0.22 g
An orbital period of 49.464 days
Semi-major axis 0.2877 AU
Distance from Earth 3,343.16 light-years
Earth Similarity Index 0.419
Travel time at Voyager 1 speed 58,956,698 years

Context from the literature

Kepler-47b is an exoplanet orbiting the binary star system Kepler-47, the innermost of three such planets discovered by NASA's Kepler spacecraft. The system, also involving two other exoplanets, is located about 3,400 light-years away.

Excerpted from Wikipedia · full article

2 siblings around Kepler-47

Kepler-47 b shares its host star with 2 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
Kepler-47 b this	Sub-Neptune	3.05	2.07	49.464	—	2012
Kepler-47 d	Neptune-like	7.04	19.02	187.366	—	2019
Kepler-47 c	Neptune-like	4.65	3.17	303.227	—	2012

brightness_6

Circumbinary planet

Kepler-47 b orbits a binary-star pair rather than a single host — a minority architecture in the confirmed catalogue.

Kepler-47 b Planet Profile

Physical Specs

Radius

3.05 R⊕

Radius (Jupiter)

0.272 R♃

Mass

2.07 M⊕

Mass (Jupiter)

0.007 M♃

Density

0.40 g/cm³

Surface Gravity

0.22 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.419

HZ Position Unknown

Controversial No

Discovery

Year 2012

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#472of 1978

top 23.8%

This planet

3.05R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-791 b 3.05 R⊕ Kepler-1204 b 3.05 R⊕ HD 168009 b 3.05 R⊕

Metric	Earth	Kepler-47 b	Jupiter
Radius (R⊕)	1.00	3.05	11.21
Mass (M⊕)	1.00	2.07	317.83
Density (g/cm³)	5.51	0.40	1.33
Surface Gravity (g)	1.00	0.22	2.53
Insolation (S⊕)	1.00	—	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	2.070 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 271548206

Gaia DR2

Gaia DR2 2080506523540902912

Gaia DR3

Gaia DR3 2080506523540902912

System

Kepler-47

Percentile among Sub-Neptune cohort

Radius 3.050 R⊕ · percentile 76 / cohort 1978

Mass 2.070 M⊕ · percentile 0 / cohort 1978

Orbital period 49.46 d · percentile 85 / cohort 1946

Distance 1,025.02 pc · percentile 80 / cohort 1975

ESI 0.419 · percentile 56 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

49.464 days

Semi-major axis

0.2877 AU

Eccentricity

0.021

Inclination

89.75 °

Year Length

A year here lasts approximately 49.46 Earth days (13.5% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.2877 AU.

Transit Fingerprint

Rp / R★

0.029840

Transit midpoint (BJD)

2,454,968.6427

Extended Orbital Architecture

Planet / star radius ratio

0.029840

Transit mid-time (BJD)

2,454,968.6427

Long. of periastron (ω)

48.60°

Angular separation (arcsec)

0.28100

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.419

0 = alien, 1 = Earth-identical

Detection Signatures

Transit photometry

A transit dip has been observed from at least one telescope.

Radial velocity

Stellar wobble has been measured spectroscopically.

Transit timing variations

Gravitational interactions from neighbours have been detected.

Discovery Paper

Primary reference

Orosz et al. 2012

Instrument

Kepler CCD Array

Publication

2012-09

Observation locale

Space

Discovery cohort

Planets confirmed in 2012 at Kepler (12 shown).

Kepler-54 c · Rocky Terrestrial Kepler-49 c · Sub-Neptune Kepler-55 b · Sub-Neptune Kepler-49 b · Sub-Neptune Kepler-81 c · Sub-Neptune Kepler-55 c · Sub-Neptune Kepler-52 c · Super-Earth Kepler-83 c · Sub-Neptune Kepler-32 d · Sub-Neptune Kepler-83 b · Sub-Neptune Kepler-54 b · Sub-Neptune Kepler-80 c · Sub-Neptune

Host System: Kepler-47

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,636 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.936 R☉

Stellar Mass

0.957 M☉

Metallicity [Fe/H]

-0.25

Extended Stellar Properties

Surface gravity (log g)

4.492 dex

Stellar density

1.650 g/cm³

Rotational v·sin i

4.10 km/s

Metallicity ratio

[M/H]

Distance

1,025.02 parsec

Light-years 3,343.16 ly

V-band magnitude

15.31 mag

Voyager-speed travel 58,956,698 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

0.948 mas

Total Proper Motion

10.655 mas/yr

PM Right Ascension

-3.49 mas/yr

PM Declination

-10.07 mas/yr

Galactic Cartesian (pc)

x = 0.292 · y = -0.618 · z = 0.730

Equatorial (J2000)

RA 295.29789° · Dec 46.92043°

Galactic ℓ, b

80.007° · 11.661°

Ecliptic λ, β

316.595° · 66.315°

HTM-20 index

-1160210418

Wikipedia → Image: Wikimedia Commons · NASA/JPL-Caltech/T. Pyle · Public domain