Key parameters at a glance

A radius of 1.20 Earth radii
A mass of 1.68 Earth masses
Surface gravity around 1.16 g
An orbital period of 0.355 days
Semi-major axis 0.0090 AU
Equilibrium temperature 2,223 K (1950 °C)
Distance from Earth 405.66 light-years
Earth Similarity Index 0.124
Travel time at Voyager 1 speed 7,153,810 years

Kepler-78 b Planet Profile

Physical Specs

Radius

1.20 R⊕

Radius (Jupiter)

0.107 R♃

Mass

1.68 M⊕

Mass (Jupiter)

0.005 M♃

Density

5.33 g/cm³

Surface Gravity

1.16 g (Earth)

Classification

Planet Type

Rocky Terrestrial

ESI Score 0.124

HZ Position Inner

Controversial No

Discovery

Year 2013

Method Transit

Facility Kepler

Telescope 0.95 m Kepler Telescope

Size rank in cohort

Rank by radius

#74of 570

top 12.8%

This planet

1.20R⊕

Rocky Terrestrial median

1.01R⊕

Nearest-size peers

Kepler-1894 b 1.20 R⊕ Kepler-225 b 1.20 R⊕ Kepler-367 c 1.20 R⊕

Metric	Earth	Kepler-78 b	Jupiter
Radius (R⊕)	1.00	1.20	11.21
Mass (M⊕)	1.00	1.68	317.83
Density (g/cm³)	5.51	5.33	1.33
Surface Gravity (g)	1.00	1.16	2.53
Insolation (S⊕)	1.00	4,070.00	0.037

Alternative Mass Estimates

Method	Value	Interpretation
Best measured mass	1.680 M⊕	Direct mass measurement (not derived).

Star Catalogue Identifiers

TIC

TIC 270701667

Gaia DR2

Gaia DR2 2078373642776670080

Gaia DR3

Gaia DR3 2078373642776670080

System

Kepler-78

Percentile among Rocky Terrestrial cohort

Radius 1.201 R⊕ · percentile 87 / cohort 570

Mass 1.680 M⊕ · percentile 68 / cohort 570

Orbital period 0.36 d · percentile 1 / cohort 567

Distance 124.38 pc · percentile 25 / cohort 566

ESI 0.124 · percentile 2 / cohort 570

Orbit & Habitability

Orbital Dynamics

Period

0.355 days

Semi-major axis

0.0090 AU

Eccentricity

0.000

Inclination

75.20 °

Year Length

A year here lasts roughly 8.5 hours long on a nearly circular orbit at a mean orbital distance of 0.0090 AU.

Transit Fingerprint

Depth

0.022 %

Duration

0.814 h

Rp / R★

0.015050

Transit midpoint (BJD)

2,454,953.9598

Photometric dip

Transit produces a flux drop of 217 ppm lasting ≈ 0.81 h.

Extended Orbital Architecture

Planet / star radius ratio

0.015050

Semi-major axis / stellar radius

2.700

RV semi-amplitude (K)

1.750 m/s

Occultation depth

0.001 ppm

Transit mid-time (BJD)

2,454,953.9598

Long. of periastron (ω)

90.00°

Angular separation (arcsec)

0.07240

Eq. Temperature

2,223K

(1950 °C)

Insolation (S⊕)

4,070.00

Earth = 1.00

Earth Similarity (ESI)

0.124

0 = alien, 1 = Earth-identical

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

Detection Signatures

Transit photometry

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

Radial velocity

Stellar wobble has been measured spectroscopically.

Orbital-brightness modulation

Host star brightness varies with the planet's orbit.

Discovery Paper

Primary reference

Sanchis Ojeda et al. 2013

Instrument

Kepler CCD Array

Publication

2013-09

Observation locale

Space

Discovery cohort

Planets confirmed in 2013 at Kepler (12 shown).

Kepler-69 c · Super-Earth Kepler-61 b · Sub-Neptune Kepler-62 e · Super-Earth KOI-351 f · Sub-Neptune Kepler-62 f · Super-Earth KOI-351 e · Sub-Neptune Kepler-1704 b · Gas Giant Kepler-37 d · Sub-Neptune Kepler-282 e · Sub-Neptune KOI-351 h · Gas Giant KOI-351 d · Sub-Neptune Kepler-114 c · Super-Earth

Host System: Kepler-78

Spectral Class

G-type yellow (Sun-like)

Effective Temperature

5,058 K — cooler than the Sun (5,778 K)

Estimated Age

0.62 Gyr — younger than the Sun (4.6 Gyr)

Stellar Radius

0.748 R☉

Stellar Mass

0.779 M☉

Metallicity [Fe/H]

-0.18

Extended Stellar Properties

Surface gravity (log g)

4.610 dex

Stellar density

2.630 g/cm³

Systemic radial velocity

-3.51 km/s

Rotational v·sin i

2.60 km/s

Rotation period

12.92 days

Metallicity ratio

[Fe/H]

Distance

124.38 parsec

Light-years 405.66 ly

V-band magnitude

11.72 mag

Voyager-speed travel 7,153,810 yr

Multi-band Host Photometry — 16 bands

Astrometric Data

Parallax

8.011 mas

Total Proper Motion

41.329 mas/yr

PM Right Ascension

38.06 mas/yr

PM Declination

-16.11 mas/yr

Galactic Cartesian (pc)

x = 0.287 · y = -0.653 · z = 0.700

Equatorial (J2000)

RA 293.74195° · Dec 44.44825°

Galactic ℓ, b

77.255° · 11.499°

Ecliptic λ, β

311.838° · 64.477°

HTM-20 index

-1639122126