Key parameters at a glance

A radius of 8.06 Earth radii
A mass of 29.88 Earth masses
Surface gravity around 0.46 g
An orbital period of 18.796 days
Semi-major axis 0.1445 AU
Equilibrium temperature 984 K (711 °C)
Distance from Earth 4,747.43 light-years
Earth Similarity Index 0.136
Travel time at Voyager 1 speed 83,720,904 years

1 sibling around Kepler-117

Kepler-117 b shares its host star with 1 other confirmed planet. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
Kepler-117 b this	Neptune-like	8.06	29.88	18.796	984	2014
Kepler-117 c	Gas Giant	12.34	584.78	50.790	704	2014

Kepler-117 b Planet Profile

Physical Specs

Radius

8.06 R⊕

Radius (Jupiter)

0.719 R♃

Mass

29.88 M⊕

Mass (Jupiter)

0.094 M♃

Density

0.30 g/cm³

Surface Gravity

0.46 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.136

HZ Position Inner

Controversial No

Discovery

Year 2014

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#153of 574

top 26.5%

This planet

8.06R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

TOI-1775 b 8.05 R⊕ Kepler-9 c 8.08 R⊕ Kepler-849 b 8.08 R⊕

Metric	Earth	Kepler-117 b	Jupiter
Radius (R⊕)	1.00	8.06	11.21
Mass (M⊕)	1.00	29.88	317.83
Density (g/cm³)	5.51	0.30	1.33
Surface Gravity (g)	1.00	0.46	2.53
Insolation (S⊕)	1.00	157.54	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	29.875 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 299032847

Gaia DR2

Gaia DR2 2130959744881558272

Gaia DR3

Gaia DR3 2130959744881558272

System

Kepler-117

Percentile among Neptune-like cohort

Radius 8.059 R⊕ · percentile 73 / cohort 574

Mass 29.875 M⊕ · percentile 49 / cohort 574

Orbital period 18.80 d · percentile 51 / cohort 524

Distance 1,455.57 pc · percentile 84 / cohort 572

ESI 0.136 · percentile 9 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

18.796 days

Semi-major axis

0.1445 AU

Eccentricity

0.049

Inclination

88.74 °

Year Length

A year here lasts approximately 18.80 Earth days (5.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1445 AU.

Transit Fingerprint

Depth

0.243 %

Duration

7.258 h

Impact parameter b

0.446

Rp / R★

0.046300

Transit midpoint (BJD)

2,454,978.8220

Photometric dip

Transit produces a flux drop of 2,431 ppm lasting ≈ 7.26 h.

Extended Orbital Architecture

Planet / star radius ratio

0.046300

Semi-major axis / stellar radius

19.670

Impact parameter (b)

0.446

RV semi-amplitude (K)

6.500 m/s

Transit mid-time (BJD)

2,454,978.8220

Long. of periastron (ω)

254.30°

Angular separation (arcsec)

0.09930

Eq. Temperature

984K

(711 °C)

Insolation (S⊕)

157.54

Earth = 1.00

Earth Similarity (ESI)

0.136

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.

Detection Signatures

Transit photometry

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

Transit timing variations

Gravitational interactions from neighbours have been detected.

Discovery Paper

Primary reference

Rowe et al. 2014

Instrument

Kepler CCD Array

Publication

2014-03

Observation locale

Space

Discovery cohort

Planets confirmed in 2014 at Kepler (12 shown).

Kepler-186 e · Super-Earth Kepler-395 c · Super-Earth Kepler-220 e · Super-Earth Kepler-249 d · Super-Earth Kepler-296 f · Super-Earth Kepler-367 c · Rocky Terrestrial Kepler-296 e · Super-Earth Kepler-155 c · Sub-Neptune Kepler-138 d · Super-Earth Kepler-333 c · Rocky Terrestrial Kepler-331 d · Super-Earth Kepler-267 d · Sub-Neptune

Host System: Kepler-117

Spectral Class

F-type yellow-white

Effective Temperature

6,150 K — hotter than the Sun (5,778 K)

Estimated Age

5.30 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.606 R☉

Stellar Mass

1.129 M☉

Metallicity [Fe/H]

-0.04

Extended Stellar Properties

Surface gravity (log g)

4.102 dex

Stellar density

0.410 g/cm³

Systemic radial velocity

-12.95 km/s

Rotational v·sin i

6.00 km/s

Metallicity ratio

[Fe/H]

Distance

1,455.57 parsec

Light-years 4,747.43 ly

V-band magnitude

14.28 mag

Voyager-speed travel 83,720,904 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

0.658 mas

Total Proper Motion

10.403 mas/yr

PM Right Ascension

3.52 mas/yr

PM Declination

-9.79 mas/yr

Galactic Cartesian (pc)

x = 0.215 · y = -0.633 · z = 0.744

Equatorial (J2000)

RA 288.79307° · Dec 48.04018°

Galactic ℓ, b

79.125° · 16.115°

Ecliptic λ, β

307.083° · 69.072°

HTM-20 index

283749976