Key parameters at a glance

A radius of 2.57 Earth radii
A mass of 7.13 Earth masses
Surface gravity around 1.08 g
An orbital period of 8.680 days
Distance from Earth 1,285.33 light-years
Earth Similarity Index 0.694
Travel time at Voyager 1 speed 22,666,711 years

K2-218 b Planet Profile

Physical Specs

Radius

2.57 R⊕

Radius (Jupiter)

0.229 R♃

Mass

7.13 M⊕

Mass (Jupiter)

0.022 M♃

Density

2.31 g/cm³

Surface Gravity

1.08 g (Earth)

Classification

Planet Type

Sub-Neptune

ESI Score 0.694

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

#1088of 1978

top 55.0%

This planet

2.57R⊕

Sub-Neptune median

2.71R⊕

Nearest-size peers

Kepler-1549 b 2.57 R⊕ Kepler-313 c 2.57 R⊕ Kepler-245 b 2.57 R⊕

Metric	Earth	K2-218 b	Jupiter
Radius (R⊕)	1.00	2.57	11.21
Mass (M⊕)	1.00	7.13	317.83
Density (g/cm³)	5.51	2.31	1.33
Surface Gravity (g)	1.00	1.08	2.53
Insolation (S⊕)	1.00	—	0.037

Star Catalogue Identifiers

TIC

TIC 266014458

Gaia DR2

Gaia DR2 2556472119215785728

Gaia DR3

Gaia DR3 2556472119215785728

System

K2-218

Percentile among Sub-Neptune cohort

Radius 2.569 R⊕ · percentile 45 / cohort 1978

Mass 7.130 M⊕ · percentile 42 / cohort 1978

Orbital period 8.68 d · percentile 29 / cohort 1946

Distance 394.08 pc · percentile 41 / cohort 1975

ESI 0.694 · percentile 92 / cohort 1978

Orbit & Habitability

Orbital Dynamics

Period

8.680 days

Semi-major axis

— AU

Eccentricity

—

Inclination

88.45 °

Year Length

A year here lasts approximately 8.68 Earth days (2.4% of a terrestrial year).

Transit Fingerprint

Depth

0.060 %

Duration

3.840 h

Rp / R★

0.023364

Transit midpoint (BJD)

2,457,396.4591

Photometric dip

Transit produces a flux drop of 598 ppm lasting ≈ 3.84 h.

Eq. Temperature

—

Insolation (S⊕)

—

Earth = 1.00

Earth Similarity (ESI)

0.694

0 = alien, 1 = Earth-identical

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: K2-218

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,757 K — cooler than the Sun (5,778 K)

Estimated Age

—

Stellar Radius

1.008 R☉

Stellar Mass

1.047 M☉

Metallicity [Fe/H]

0.25

Extended Stellar Properties

Surface gravity (log g)

4.450 dex

Stellar density

1.213 g/cm³

Systemic radial velocity

-0.34 km/s

Metallicity ratio

[Fe/H]

Distance

394.08 parsec

Light-years 1,285.33 ly

V-band magnitude

12.92 mag

Voyager-speed travel 22,666,711 yr

Multi-band Host Photometry — 17 bands

Astrometric Data

Parallax

2.510 mas

Total Proper Motion

13.995 mas/yr

PM Right Ascension

-11.45 mas/yr

PM Declination

-8.05 mas/yr

Galactic Cartesian (pc)

x = 0.968 · y = 0.220 · z = 0.119

Equatorial (J2000)

RA 12.80961° · Dec 6.84643°

Galactic ℓ, b

122.843° · -56.025°

Ecliptic λ, β

14.441° · 1.250°

HTM-20 index

1936026642