Key parameters at a glance
- A radius of 2.20 Earth radii
- A mass of 5.48 Earth masses
- Surface gravity around 1.13 g
- An orbital period of 21.587 days
- Semi-major axis 0.1550 AU
- Equilibrium temperature 747 K (474 °C)
- Distance from Earth 3,351.09 light-years
- Earth Similarity Index 0.356
- Travel time at Voyager 1 speed 59,096,466 years
4 siblings around Kepler-122
Kepler-122 d 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 this | Sub-Neptune | 2.20 | 5.48 | 21.587 | 747 | 2014 |
| Kepler-122 e | 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 d Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1673of 1978
top 84.5%
This planet
2.20R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | Kepler-122 d | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.20 | 11.21 |
| Mass (M⊕) | 1.00 | 5.48 | 317.83 |
| Density (g/cm³) | 5.51 | 2.83 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.13 | 2.53 |
| Insolation (S⊕) | 1.00 | 77.14 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 122714267
Gaia DR2
Gaia DR2 2053070616052194304
Gaia DR3
Gaia DR3 2053070616052194304
System
Kepler-122
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 21.59 Earth days (5.9% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.1550 AU.
Transit Fingerprint
Depth
0.034 %
Duration
4.683 h
Impact parameter b
0.010
Rp / R★
0.016798
Transit midpoint (BJD)
2,454,975.9729
Photometric dip
Transit produces a flux drop of 337 ppm lasting ≈ 4.68 h.
Extended Orbital Architecture
Planet / star radius ratio
0.016798
Semi-major axis / stellar radius
37.800
Impact parameter (b)
0.010
Transit mid-time (BJD)
2,454,975.9729
Angular separation (arcsec)
0.15100
Eq. Temperature
747K
(474 °C)
Insolation (S⊕)
77.14
Earth = 1.00
Earth Similarity (ESI)
0.356
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.
Discovery Paper
Primary reference
Rowe et al. 2014Instrument
Kepler CCD Array
Publication
2014-03
Observation locale
Space
Discovery cohort
Planets confirmed in 2014 at Kepler (12 shown).
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]
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
Similar Worlds
Kepler-84 f
Sub-Neptune · F-type yellow-white
Radius 2.20 R⊕ · 3,339.5 ly
Kepler-1137 b
Sub-Neptune · F-type yellow-white
Radius 2.20 R⊕ · 3,006.4 ly
K2-335 b
Sub-Neptune · F-type yellow-white
Radius 2.21 R⊕ · 1,819.9 ly
TOI-128.01
Sub-Neptune · F-type yellow-white
Radius 2.22 R⊕ · 223.3 ly
Kepler-1949 b
Sub-Neptune · F-type yellow-white
Radius 2.22 R⊕ · 8,536.6 ly
TOI-1408 c
Sub-Neptune · F-type yellow-white
Radius 2.22 R⊕ · 454.9 ly