Key parameters at a glance

A radius of 1.96 Earth radii
A mass of 1.63 Earth masses
Surface gravity around 0.42 g
An orbital period of 5.910 days
Semi-major axis 0.0569 AU
Equilibrium temperature 585 K (312 °C)
Distance from Earth 1,429.73 light-years
Earth Similarity Index 0.398
Travel time at Voyager 1 speed 25,213,361 years
Almost certainly tidally locked to its host star given the close orbit

1 sibling around Kepler-28

Kepler-28 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
Kepler-28 b this	Super-Earth	1.96	1.63	5.910	585	2011
Kepler-28 c	Super-Earth	1.86	2.06	8.990	509	2011

Kepler-28 b Planet Profile

Physical Specs

Radius

1.96 R⊕

Radius (Jupiter)

0.175 R♃

Mass

1.63 M⊕

Mass (Jupiter)

0.005 M♃

Density

1.19 g/cm³

Surface Gravity

0.42 g (Earth)

Classification

Planet Type

Super-Earth

ESI Score 0.398

HZ Position Inner

Controversial No

Discovery

Year 2011

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#66of 1176

top 5.5%

This planet

1.96R⊕

Super-Earth median

1.60R⊕

Nearest-size peers

Kepler-1923 b 1.96 R⊕ Kepler-174 b 1.96 R⊕ Kepler-118 b 1.96 R⊕

Metric	Earth	Kepler-28 b	Jupiter
Radius (R⊕)	1.00	1.96	11.21
Mass (M⊕)	1.00	1.63	317.83
Density (g/cm³)	5.51	1.19	1.33
Surface Gravity (g)	1.00	0.42	2.53
Insolation (S⊕)	1.00	62.58	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	1.630 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 63122956

Gaia DR2

Gaia DR2 2125731464014361088

Gaia DR3

Gaia DR3 2125731464014361088

System

Kepler-28

Percentile among Super-Earth cohort

Radius 1.959 R⊕ · percentile 94 / cohort 1176

Mass 1.630 M⊕ · percentile 1 / cohort 1176

Orbital period 5.91 d · percentile 47 / cohort 1164

Distance 438.36 pc · percentile 43 / cohort 1171

ESI 0.398 · percentile 60 / cohort 1176

Orbit & Habitability

Orbital Dynamics

Period

5.910 days

Semi-major axis

0.0569 AU

Eccentricity

0.000

Inclination

89.51 °

Year Length

A year here lasts approximately 5.91 Earth days (1.6% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0569 AU.

Transit Fingerprint

Depth

0.106 %

Duration

2.325 h

Impact parameter b

0.170

Rp / R★

0.027826

Transit midpoint (BJD)

2,455,005.1843

Photometric dip

Transit produces a flux drop of 1,063 ppm lasting ≈ 2.33 h.

Extended Orbital Architecture

Planet / star radius ratio

0.027826

Semi-major axis / stellar radius

19.700

Impact parameter (b)

0.170

Transit mid-time (BJD)

2,455,005.1843

Angular separation (arcsec)

0.13000

Eq. Temperature

585K

(312 °C)

Insolation (S⊕)

62.58

Earth = 1.00

Earth Similarity (ESI)

0.398

0 = alien, 1 = Earth-identical

Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water. Close-orbiting tidally-locked around a cool host.

Detection Signatures

Transit photometry

A transit dip has been observed from at least one telescope.

Transit timing variations

Gravitational interactions from neighbours have been detected.

Discovery Paper

Primary reference

Steffen et al. 2012

Instrument

Kepler CCD Array

Publication

2012-04

Observation locale

Space

Discovery cohort

Planets confirmed in 2011 at Kepler (12 shown).

Kepler-22 b · Sub-Neptune Kepler-20 d · Sub-Neptune Kepler-26 c · Sub-Neptune Kepler-19 c · Sub-Neptune Kepler-26 b · Sub-Neptune Kepler-28 c · Super-Earth Kepler-10 c · Sub-Neptune Kepler-20 f · Rocky Terrestrial Kepler-42 d · Rocky Terrestrial Kepler-16 b · Neptune-like Kepler-34 b · Neptune-like Kepler-29 c · Sub-Neptune

Host System: Kepler-28

Spectral Class

M-type red dwarf

Effective Temperature

4,499 K — cooler than the Sun (5,778 K)

Estimated Age

1.91 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.664 R☉

Stellar Mass

0.684 M☉

Metallicity [Fe/H]

0.15

Extended Stellar Properties

Surface gravity (log g)

4.620 dex

Stellar density

3.271 g/cm³

Metallicity ratio

[M/H]

Distance

438.36 parsec

Light-years 1,429.73 ly

V-band magnitude

15.13 mag

Voyager-speed travel 25,213,361 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

2.253 mas

Total Proper Motion

11.702 mas/yr

PM Right Ascension

-0.49 mas/yr

PM Declination

11.69 mas/yr

Galactic Cartesian (pc)

x = 0.278 · y = -0.684 · z = 0.675

Equatorial (J2000)

RA 292.13704° · Dec 42.42948°

Galactic ℓ, b

74.881° · 11.639°

Ecliptic λ, β

307.770° · 62.995°

HTM-20 index

-242081587