Key parameters at a glance

A radius of 1.03 Earth radii
A mass of 1.08 Earth masses
Surface gravity around 1.02 g
An orbital period of 3.851 days
Equilibrium temperature 783 K (510 °C)
Distance from Earth 511.91 light-years
Earth Similarity Index 0.418
Travel time at Voyager 1 speed 9,027,446 years
Almost certainly tidally locked to its host star given the close orbit

K2-338 b Planet Profile

Physical Specs

Radius

1.03 R⊕

Radius (Jupiter)

0.092 R♃

Mass

1.08 M⊕

Mass (Jupiter)

0.003 M♃

Density

5.43 g/cm³

Surface Gravity

1.02 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.418

HZ Position Unknown

Controversial No

Discovery

Year 2021

Method Transit

Facility K2

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#297of 570

top 51.9%

This planet

1.03R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-395 b 1.03 R⊕ Kepler-387 b 1.03 R⊕ Kepler-1398 c 1.03 R⊕

Metric	Earth	K2-338 b	Jupiter
Radius (R⊕)	1.00	1.03	11.21
Mass (M⊕)	1.00	1.08	317.83
Density (g/cm³)	5.51	5.43	1.33
Surface Gravity (g)	1.00	1.02	2.53
Insolation (S⊕)	1.00	—	0.037

Star Catalogue Identifiers

TIC

TIC 186814470

Gaia DR2

Gaia DR2 656201703533465088

Gaia DR3

Gaia DR3 656201703533465088

System

K2-338

Percentile among Rocky Terrestrial cohort

Radius 1.030 R⊕ · percentile 46 / cohort 570

Mass 1.080 M⊕ · percentile 41 / cohort 570

Orbital period 3.85 d · percentile 41 / cohort 567

Distance 156.95 pc · percentile 28 / cohort 566

ESI 0.418 · percentile 62 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

3.851 days

Semi-major axis

— AU

Eccentricity

—

Inclination

— °

Year Length

A year here lasts approximately 3.85 Earth days (1.1% of a terrestrial year).

Transit Fingerprint

Depth

0.039 %

Duration

1.780 h

Impact parameter b

0.420

Rp / R★

0.014800

Transit midpoint (BJD)

2,457,141.5263

Photometric dip

Transit produces a flux drop of 391 ppm lasting ≈ 1.78 h.

Extended Orbital Architecture

Planet / star radius ratio

0.014800

Semi-major axis / stellar radius

15.130

Impact parameter (b)

0.420

Transit mid-time (BJD)

2,457,141.5263

Eq. Temperature

783K

(510 °C)

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.418

0 = alien, 1 = Earth-identical

Insufficient insolation data — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

Discovery Paper

Primary reference

De Leon et al. 2021

Instrument

Kepler CCD Array

Publication

2021-08

Observation locale

Space

Discovery cohort

Planets confirmed in 2021 at K2 (12 shown).

EPIC 220492298 b · Rocky Terrestrial EPIC 206042996 c · Rocky Terrestrial EPIC 212624936 b · Rocky Terrestrial EPIC 206024342 c · Super-Earth EPIC 201427007 b · Super-Earth K2-332 b · Sub-Neptune EPIC 212624936 c · Sub-Neptune EPIC 206024342 d · Sub-Neptune K2-345 b · Sub-Neptune K2-349 b · Super-Earth K2-343 c · Sub-Neptune K2-346 b · Sub-Neptune

Host System: K2-338

Spectral Class

K-type orange

Effective Temperature

4,558 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

0.630 R☉

Stellar Mass

0.660 M☉

Metallicity [Fe/H]

-0.23

Extended Stellar Properties

Surface gravity (log g)

4.650 dex

Stellar density

4.050 g/cm³

Metallicity ratio

[Fe/H]

Distance

156.95 parsec

Light-years 511.91 ly

V-band magnitude

13.32 mag

Voyager-speed travel 9,027,446 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

6.343 mas

Total Proper Motion

59.082 mas/yr

PM Right Ascension

-33.74 mas/yr

PM Declination

-48.50 mas/yr

Galactic Cartesian (pc)

x = -0.540 · y = 0.789 · z = 0.293

Equatorial (J2000)

RA 124.36093° · Dec 17.02416°

Galactic ℓ, b

206.470° · 26.450°

Ecliptic λ, β

122.695° · -2.600°

HTM-20 index

-1284986209