Key parameters at a glance
- A radius of 2.15 Earth radii
- A mass of 8.50 Earth masses
- Surface gravity around 1.84 g
- An orbital period of 6.313 days
- Semi-major axis 0.0550 AU
- Equilibrium temperature 575 K (302 °C)
- Distance from Earth 1,267.54 light-years
- Earth Similarity Index 0.486
- Travel time at Voyager 1 speed 22,353,068 years
- Almost certainly tidally locked to its host star given the close orbit
1 sibling around Kepler-120
Kepler-120 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-120 b this | Sub-Neptune | 2.15 | 8.50 | 6.313 | 575 | 2014 |
| Kepler-120 c | Super-Earth | 1.53 | 2.96 | 12.795 | 455 | 2014 |
Kepler-120 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#1741of 1978
top 88.0%
This planet
2.15R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | Kepler-120 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.15 | 11.21 |
| Mass (M⊕) | 1.00 | 8.50 | 317.83 |
| Density (g/cm³) | 5.51 | 4.70 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.84 | 2.53 |
| Insolation (S⊕) | 1.00 | 42.69 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 8.500 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 121458707
Gaia DR2
Gaia DR2 2099740761478810624
Gaia DR3
Gaia DR3 2099740761478810624
System
Kepler-120
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 6.31 Earth days (1.7% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0550 AU.
Transit Fingerprint
Depth
0.129 %
Duration
2.908 h
Impact parameter b
0.790
Rp / R★
0.033000
Transit midpoint (BJD)
2,454,965.6542
Photometric dip
Transit produces a flux drop of 1,286 ppm lasting ≈ 2.91 h.
Extended Orbital Architecture
Planet / star radius ratio
0.033000
Semi-major axis / stellar radius
18.129
Impact parameter (b)
0.790
Transit mid-time (BJD)
2,454,965.6542
Angular separation (arcsec)
0.14200
Eq. Temperature
575K
(302 °C)
Insolation (S⊕)
42.69
Earth = 1.00
Earth Similarity (ESI)
0.486
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.
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-120
Spectral Class
M-type red dwarf
Effective Temperature
4,096 K — cooler than the Sun (5,778 K)
Estimated Age
3.63 Gyr — younger than the Sun (4.6 Gyr)
Stellar Radius
0.534 R☉
Stellar Mass
0.654 M☉
Metallicity [Fe/H]
-0.12
Extended Stellar Properties
Surface gravity (log g)
4.732 dex
Stellar density
2.776 g/cm³
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 17 bands
Astrometric Data
Parallax
2.544 mas
Total Proper Motion
11.812 mas/yr
PM Right Ascension
-10.18 mas/yr
PM Declination
-5.99 mas/yr
Galactic Cartesian (pc)
x = 0.238 · y = -0.736 · z = 0.634
Equatorial (J2000)
RA 287.89157° · Dec 39.33910°
Galactic ℓ, b
70.616° · 13.219°
Ecliptic λ, β
299.313° · 60.970°
HTM-20 index
-623648866
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