Key parameters at a glance

A radius of 9.76 Earth radii
A mass of 68.70 Earth masses
Surface gravity around 0.72 g
An orbital period of 3.896 days
Semi-major axis 0.0460 AU
Equilibrium temperature 1,005 K (732 °C)
Distance from Earth 4,428.38 light-years
Earth Similarity Index 0.135
Travel time at Voyager 1 speed 78,094,531 years

Kepler-688 b Planet Profile

Physical Specs

Radius

9.76 R⊕

Radius (Jupiter)

0.871 R♃

Mass

68.70 M⊕

Mass (Jupiter)

0.216 M♃

Density

0.41 g/cm³

Surface Gravity

0.72 g (Earth)

Classification

Planet Type

Neptune-like

ESI Score 0.135

HZ Position Inner

Controversial No

Discovery

Year 2016

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#19of 574

top 3.1%

This planet

9.76R⊕

Neptune-like median

6.39R⊕

Nearest-size peers

Kepler-1517 b 9.76 R⊕ TOI-1859 b 9.75 R⊕ TOI-5573 b 9.75 R⊕

Metric	Earth	Kepler-688 b	Jupiter
Radius (R⊕)	1.00	9.76	11.21
Mass (M⊕)	1.00	68.70	317.83
Density (g/cm³)	5.51	0.41	1.33
Surface Gravity (g)	1.00	0.72	2.53
Insolation (S⊕)	1.00	458.91	0.037

Star Catalogue Identifiers

TIC

TIC 378085713

Gaia DR2

Gaia DR2 2052232410241029248

Gaia DR3

Gaia DR3 2052232410241029248

System

Kepler-688

Percentile among Neptune-like cohort

Radius 9.760 R⊕ · percentile 97 / cohort 574

Mass 68.700 M⊕ · percentile 85 / cohort 574

Orbital period 3.90 d · percentile 11 / cohort 524

Distance 1,357.75 pc · percentile 82 / cohort 572

ESI 0.135 · percentile 8 / cohort 574

Orbit & Habitability

Orbital Dynamics

Period

3.896 days

Semi-major axis

0.0460 AU

Eccentricity

0.000

Inclination

87.56 °

Year Length

A year here lasts approximately 3.90 Earth days (1.1% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0460 AU.

Transit Fingerprint

Depth

0.854 %

Duration

2.339 h

Impact parameter b

0.541

Rp / R★

0.092867

Transit midpoint (BJD)

2,455,003.5275

Photometric dip

Transit produces a flux drop of 8,545 ppm lasting ≈ 2.34 h.

Extended Orbital Architecture

Planet / star radius ratio

0.092867

Semi-major axis / stellar radius

12.300

Impact parameter (b)

0.541

Transit mid-time (BJD)

2,455,003.5275

Angular separation (arcsec)

0.03390

Eq. Temperature

1,005K

(732 °C)

Insolation (S⊕)

458.91

Earth = 1.00

Earth Similarity (ESI)

0.135

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the dayside is scorched.

Discovery Paper

Primary reference

Morton et al. 2016

Instrument

Kepler CCD Array

Publication

2016-05

Observation locale

Space

Discovery cohort

Planets confirmed in 2016 at Kepler (12 shown).

Kepler-1512 b · Rocky Terrestrial Kepler-1410 b · Super-Earth Kepler-560 b · Super-Earth Kepler-1389 b · Super-Earth Kepler-1450 b · Super-Earth Kepler-1544 b · Super-Earth Kepler-1459 b · Super-Earth Kepler-1638 b · Super-Earth Kepler-737 b · Super-Earth Kepler-1185 b · Super-Earth Kepler-1178 b · Rocky Terrestrial Kepler-1040 b · Sub-Neptune

Host System: Kepler-688

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,715 K — cooler than the Sun (5,778 K)

Estimated Age

4.27 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.960 R☉

Stellar Mass

0.980 M☉

Metallicity [Fe/H]

0.02

Extended Stellar Properties

Surface gravity (log g)

4.470 dex

Stellar density

2.212 g/cm³

Metallicity ratio

[Fe/H]

Distance

1,357.75 parsec

Light-years 4,428.38 ly

V-band magnitude

15.81 mag

Voyager-speed travel 78,094,531 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

0.709 mas

Total Proper Motion

1.530 mas/yr

PM Right Ascension

1.13 mas/yr

PM Declination

-1.03 mas/yr

Galactic Cartesian (pc)

x = 0.323 · y = -0.703 · z = 0.633

Equatorial (J2000)

RA 294.65523° · Dec 39.30834°

Galactic ℓ, b

72.949° · 8.516°

Ecliptic λ, β

309.379° · 59.422°

HTM-20 index

-1984213892