Key parameters at a glance
- A radius of 1.00 Earth radii
- A mass of 2.55 Earth masses
- Surface gravity around 2.55 g
- An orbital period of 0.584 days
- Semi-major axis 0.0131 AU
- Equilibrium temperature 1,818 K (1545 °C)
- Distance from Earth 334.52 light-years
- Earth Similarity Index 0.149
- Travel time at Voyager 1 speed 5,899,236 years
1 sibling around K2-229
K2-229 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 |
|---|---|---|---|---|---|---|
| K2-229 b this | Rocky Terrestrial | 1.00 | 2.55 | 0.584 | 1,818 | 2018 |
| K2-229 c | Sub-Neptune | 2.03 | 7.00 | 8.327 | 750 | 2018 |
K2-229 b Planet Profile
Physical Specs
Classification
Planet Type
Rocky Terrestrial
Discovery
Size rank in cohort
Rank by radius
#335of 570
top 58.6%
This planet
1.00R⊕
Rocky Terrestrial median
1.01R⊕
Nearest-size peers
| Metric | Earth | K2-229 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 1.00 | 11.21 |
| Mass (M⊕) | 1.00 | 2.55 | 317.83 |
| Density (g/cm³) | 5.51 | 7.60 | 1.33 |
| Surface Gravity (g) | 1.00 | 2.55 | 2.53 |
| Insolation (S⊕) | 1.00 | 2,290.00 | 0.037 |
Alternative Mass Estimates
| Method | Value | Interpretation |
|---|---|---|
| Best measured mass | 2.550 M⊕ | Direct mass measurement (not derived). |
Star Catalogue Identifiers
TIC
TIC 98720809
Gaia DR2
Gaia DR2 3583630929786305280
Gaia DR3
Gaia DR3 3583630934082556416
System
K2-229
Percentile among Rocky Terrestrial cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts roughly 14 hours long on a nearly circular orbit at a mean orbital distance of 0.0131 AU.
Transit Fingerprint
Depth
0.016 %
Duration
1.500 h
Impact parameter b
0.380
Rp / R★
0.011800
Transit midpoint (BJD)
2,457,646.5666
Photometric dip
Transit produces a flux drop of 163 ppm lasting ≈ 1.50 h.
Extended Orbital Architecture
Planet / star radius ratio
0.011800
Semi-major axis / stellar radius
4.200
Impact parameter (b)
0.380
RV semi-amplitude (K)
2.200 m/s
Transit mid-time (BJD)
2,457,646.5666
Angular separation (arcsec)
0.12800
Eq. Temperature
1,818K
(1545 °C)
Insolation (S⊕)
2,290.00
Earth = 1.00
Earth Similarity (ESI)
0.149
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.
Detection Signatures
Transit photometry
A transit dip has been observed from at least one telescope.
Radial velocity
Stellar wobble has been measured spectroscopically.
Discovery Paper
Primary reference
Mayo et al. 2018Instrument
Kepler CCD Array
Publication
2018-03
Observation locale
Space
Discovery cohort
Planets confirmed in 2018 at K2 (12 shown).
Host System: K2-229
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,315 K — cooler than the Sun (5,778 K)
Estimated Age
5.40 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
0.790 R☉
Stellar Mass
0.870 M☉
Metallicity [Fe/H]
-0.09
Extended Stellar Properties
Surface gravity (log g)
4.600 dex
Stellar density
2.380 g/cm³
Rotational v·sin i
2.46 km/s
Rotation period
18.10 days
Activity index (log R'HK)
-4.603
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 12 bands
Astrometric Data
Parallax
9.723 mas
Total Proper Motion
81.227 mas/yr
PM Right Ascension
-80.89 mas/yr
PM Declination
7.43 mas/yr
Galactic Cartesian (pc)
x = -0.986 · y = -0.119 · z = -0.117
Equatorial (J2000)
RA 186.87292° · Dec -6.72185°
Galactic ℓ, b
292.352° · 55.657°
Ecliptic λ, β
188.964° · -3.447°
HTM-20 index
827102690
Similar Worlds
Kepler-392 b
Rocky Terrestrial · G-type yellow (Sun-like)
Radius 1.00 R⊕ · 2,222.5 ly
Kepler-1417 b
Rocky Terrestrial · G-type yellow (Sun-like)
Radius 1.00 R⊕ · 3,235.0 ly
Kepler-1464 c
Rocky Terrestrial · G-type yellow (Sun-like)
Radius 1.00 R⊕ · 3,756.4 ly
Kepler-1800 b
Rocky Terrestrial · G-type yellow (Sun-like)
Radius 1.00 R⊕ · 1,143.0 ly
Kepler-1081 b
Rocky Terrestrial · G-type yellow (Sun-like)
Radius 1.01 R⊕ · 1,370.6 ly
Kepler-969 c
Rocky Terrestrial · G-type yellow (Sun-like)
Radius 0.99 R⊕ · 1,273.2 ly