Key parameters at a glance

A radius of 1.35 Earth radii
A mass of 2.39 Earth masses
Surface gravity around 1.31 g
An orbital period of 1.742 days
Semi-major axis 0.0289 AU
Equilibrium temperature 1,692 K (1419 °C)
Distance from Earth 1,457.33 light-years
Earth Similarity Index 0.169
Travel time at Voyager 1 speed 25,700,075 years

1 sibling around K2-188

K2-188 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
K2-188 b this	Super-Earth	1.35	2.39	1.742	1,692	2018
K2-188 c	Sub-Neptune	2.83	8.40	7.810	1,026	2018

K2-188 b Planet Profile

Physical Specs

Radius

1.35 R⊕

Radius (Jupiter)

0.120 R♃

Mass

2.39 M⊕

Mass (Jupiter)

0.008 M♃

Density

5.34 g/cm³

Surface Gravity

1.31 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.169

HZ Position Unknown

Controversial No

Discovery

Year 2018

Method Transit

Facility K2

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#996of 1176

top 84.6%

This planet

1.35R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Kepler-446 d 1.35 R⊕ Kepler-1532 b 1.35 R⊕ Kepler-301 c 1.35 R⊕

Metric	Earth	K2-188 b	Jupiter
Radius (R⊕)	1.00	1.35	11.21
Mass (M⊕)	1.00	2.39	317.83
Density (g/cm³)	5.51	5.34	1.33
Surface Gravity (g)	1.00	1.31	2.53
Insolation (S⊕)	1.00	—	0.037

Star Catalogue Identifiers

TIC

TIC 175236511

Gaia DR2

Gaia DR2 666195851913506816

Gaia DR3

Gaia DR3 666195851913506816

System

K2-188

Percentile among Super-Earth cohort

Radius 1.350 R⊕ · percentile 14 / cohort 1176

Mass 2.390 M⊕ · percentile 14 / cohort 1176

Orbital period 1.74 d · percentile 10 / cohort 1164

Distance 446.82 pc · percentile 43 / cohort 1171

ESI 0.169 · percentile 7 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period

1.742 days

Semi-major axis

0.0289 AU

Eccentricity

—

Inclination

83.93 °

Year Length

A year here lasts approximately 1.74 Earth days (0.5% of a terrestrial year) at a mean orbital distance of 0.0289 AU.

Transit Fingerprint

Impact parameter b

0.400

Rp / R★

0.010400

Transit midpoint (BJD)

2,457,140.4762

Extended Orbital Architecture

Planet / star radius ratio

0.010400

Semi-major axis / stellar radius

4.670

Impact parameter (b)

0.400

Transit mid-time (BJD)

2,457,140.4762

Angular separation (arcsec)

0.06470

Eq. Temperature

1,692K

(1419 °C)

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.169

0 = alien, 1 = Earth-identical

Insufficient insolation data — the dayside is scorched.

Discovery Paper

Primary reference

Mayo et al. 2018

Instrument

Kepler CCD Array

Publication

2018-03

Observation locale

Space

Discovery cohort

Planets confirmed in 2018 at K2 (12 shown).

K2-190 c · Rocky Terrestrial K2-183 b · Rocky Terrestrial K2-209 b · Rocky Terrestrial K2-210 b · Rocky Terrestrial K2-165 b · Super-Earth K2-169 b · Super-Earth K2-148 b · Super-Earth K2-219 b · Super-Earth K2-190 b · Super-Earth K2-200 b · Super-Earth K2-201 b · Super-Earth K2-170 b · Super-Earth

Host System: K2-188

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,977 K — hotter than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

1.190 R☉

Stellar Mass

1.060 M☉

Metallicity [Fe/H]

-0.01

Extended Stellar Properties

Surface gravity (log g)

4.310 dex

Stellar density

0.836 g/cm³

Systemic radial velocity

-34.21 km/s

Metallicity ratio

[Fe/H]

Distance

446.82 parsec

Light-years 1,457.33 ly

V-band magnitude

12.66 mag

Voyager-speed travel 25,700,075 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

2.210 mas

Total Proper Motion

16.765 mas/yr

PM Right Ascension

13.18 mas/yr

PM Declination

-10.37 mas/yr

Galactic Cartesian (pc)

x = -0.588 · y = 0.705 · z = 0.396

Equatorial (J2000)

RA 129.81370° · Dec 23.35744°

Galactic ℓ, b

201.660° · 33.445°

Ecliptic λ, β

126.144° · 4.775°

HTM-20 index

-143642014