Key parameters at a glance

A radius of 2.60 Earth radii
A mass of 27.70 Earth masses
Surface gravity around 4.10 g
An orbital period of 37.993 days
Semi-major axis 0.2270 AU
Equilibrium temperature 618 K (345 °C)
Distance from Earth 3,351.09 light-years
Earth Similarity Index 0.400
Travel time at Voyager 1 speed 59,096,466 years

4 siblings around Kepler-122

Kepler-122 e shares its host star with 4 other confirmed planets. Side-by-side measurements below.

Planet	Type	Radius (R⊕)	Mass (M⊕)	Period (d)	Eq. T (K)	Year
Kepler-122 b	Sub-Neptune	2.34	6.08	5.766	1,159	2014
Kepler-122 c	Neptune-like	5.87	29.00	12.466	897	2014
Kepler-122 d	Sub-Neptune	2.20	5.48	21.587	747	2014
Kepler-122 e this	Sub-Neptune	2.60	27.70	37.993	618	2014
Kepler-122 f	Super-Earth	1.75	36.00	56.268	543	2014

Kepler-122 e Planet Profile

Physical Specs

Radius

2.60 R⊕

Radius (Jupiter)

0.232 R♃

Mass

27.70 M⊕

Mass (Jupiter)

0.087 M♃

Density

8.66 g/cm³

Surface Gravity

4.10 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.400

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

#1017of 1978

top 51.4%

This planet

2.60R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

K2-155 c 2.60 R⊕ Kepler-84 e 2.60 R⊕ Kepler-115 c 2.60 R⊕

Metric	Earth	Kepler-122 e	Jupiter
Radius (R⊕)	1.00	2.60	11.21
Mass (M⊕)	1.00	27.70	317.83
Density (g/cm³)	5.51	8.66	1.33
Surface Gravity (g)	1.00	4.10	2.53
Insolation (S⊕)	1.00	36.30	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	27.700 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 122714267

Gaia DR2

Gaia DR2 2053070616052194304

Gaia DR3

Gaia DR3 2053070616052194304

System

Kepler-122

Percentile among Sub-Neptune cohort

Radius 2.600 R⊕ · percentile 48 / cohort 1978

Mass 27.700 M⊕ · percentile 97 / cohort 1978

Orbital period 37.99 d · percentile 79 / cohort 1946

Distance 1,027.45 pc · percentile 80 / cohort 1975

ESI 0.400 · percentile 52 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

37.993 days

Semi-major axis

0.2270 AU

Eccentricity

0.000

Inclination

89.97 °

Year Length

A year here lasts approximately 37.99 Earth days (10.4% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.2270 AU.

Transit Fingerprint

Depth

0.040 %

Duration

7.155 h

Impact parameter b

0.840

Rp / R★

0.018389

Transit midpoint (BJD)

2,454,996.0155

Photometric dip

Transit produces a flux drop of 404 ppm lasting ≈ 7.16 h.

Extended Orbital Architecture

Planet / star radius ratio

0.018389

Semi-major axis / stellar radius

43.624

Impact parameter (b)

0.840

Transit mid-time (BJD)

2,454,996.0155

Angular separation (arcsec)

0.22100

Eq. Temperature

618K

(345 °C)

Insolation (S⊕)

36.30

Earth = 1.00

Earth Similarity (ESI)

0.400

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-122

Spectral Class

F-type yellow-white

Effective Temperature

6,050 K — hotter than the Sun (5,778 K)

Estimated Age

7.94 Gyr — older than the Sun (4.6 Gyr)

Stellar Radius

1.216 R☉

Stellar Mass

0.982 M☉

Metallicity [Fe/H]

-0.08

Extended Stellar Properties

Surface gravity (log g)

4.299 dex

Stellar density

0.530 g/cm³

Metallicity ratio

[Fe/H]

Distance

1,027.45 parsec

Light-years 3,351.09 ly

V-band magnitude

14.40 mag

Voyager-speed travel 59,096,466 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

0.945 mas

Total Proper Motion

7.687 mas/yr

PM Right Ascension

-2.88 mas/yr

PM Declination

-7.13 mas/yr

Galactic Cartesian (pc)

x = 0.276 · y = -0.715 · z = 0.642

Equatorial (J2000)

RA 291.11186° · Dec 39.94902°

Galactic ℓ, b

72.262° · 11.237°

Ecliptic λ, β

304.565° · 60.879°

HTM-20 index

1565371838