Key parameters at a glance
- A radius of 2.90 Earth radii
- A mass of 8.75 Earth masses
- Surface gravity around 1.04 g
- An orbital period of 9.577 days
- Semi-major axis 0.0850 AU
- Equilibrium temperature 846 K (573 °C)
- Distance from Earth 2,335.36 light-years
- Earth Similarity Index 0.282
- Travel time at Voyager 1 speed 41,184,045 years
2 siblings around Kepler-178
Kepler-178 b shares its host star with 2 other confirmed planets. Side-by-side measurements below.
| Planet | Type | Radius (R⊕) | Mass (M⊕) | Period (d) | Eq. T (K) | Year |
|---|---|---|---|---|---|---|
| Kepler-178 b this | Sub-Neptune | 2.90 | 8.75 | 9.577 | 846 | 2014 |
| Kepler-178 c | Sub-Neptune | 2.88 | 8.65 | 20.553 | 656 | 2014 |
| Kepler-178 d | Sub-Neptune | 3.95 | 14.80 | 96.679 | 392 | 2014 |
Kepler-178 b Planet Profile
Physical Specs
Classification
Planet Type
Sub-Neptune
Discovery
Size rank in cohort
Rank by radius
#621of 1978
top 31.3%
This planet
2.90R⊕
Sub-Neptune median
2.71R⊕
Nearest-size peers
| Metric | Earth | Kepler-178 b | Jupiter |
|---|---|---|---|
| Radius (R⊕) | 1.00 | 2.90 | 11.21 |
| Mass (M⊕) | 1.00 | 8.75 | 317.83 |
| Density (g/cm³) | 5.51 | 1.97 | 1.33 |
| Surface Gravity (g) | 1.00 | 1.04 | 2.53 |
| Insolation (S⊕) | 1.00 | 84.57 | 0.037 |
Star Catalogue Identifiers
TIC
TIC 158394235
Gaia DR2
Gaia DR2 2130634667395736704
Gaia DR3
Gaia DR3 2130634667395736704
System
Kepler-178
Percentile among Sub-Neptune cohort
Orbit & Habitability
Orbital Dynamics
Year Length
A year here lasts approximately 9.58 Earth days (2.6% of a terrestrial year) on a nearly circular orbit at a mean orbital distance of 0.0850 AU.
Transit Fingerprint
Depth
0.075 %
Duration
3.377 h
Impact parameter b
0.490
Rp / R★
0.024883
Transit midpoint (BJD)
2,455,009.6813
Photometric dip
Transit produces a flux drop of 747 ppm lasting ≈ 3.38 h.
Extended Orbital Architecture
Planet / star radius ratio
0.024883
Semi-major axis / stellar radius
22.293
Impact parameter (b)
0.490
Transit mid-time (BJD)
2,455,009.6813
Angular separation (arcsec)
0.11900
Eq. Temperature
846K
(573 °C)
Insolation (S⊕)
84.57
Earth = 1.00
Earth Similarity (ESI)
0.282
0 = alien, 1 = Earth-identical
Inside the inner HZ boundary (too hot for liquid water) — the surface is too hot to retain surface water.
Discovery Paper
Primary reference
Rowe et al. 2014Instrument
Kepler CCD Array
Publication
2014-03
Observation locale
Space
Discovery cohort
Planets confirmed in 2014 at Kepler (12 shown).
Host System: Kepler-178
Spectral Class
G-type yellow (Sun-like)
Effective Temperature
5,676 K — cooler than the Sun (5,778 K)
Estimated Age
9.12 Gyr — older than the Sun (4.6 Gyr)
Stellar Radius
1.066 R☉
Stellar Mass
0.852 M☉
Metallicity [Fe/H]
-0.04
Extended Stellar Properties
Surface gravity (log g)
4.334 dex
Stellar density
1.250 g/cm³
Metallicity ratio
[Fe/H]
Multi-band Host Photometry — 16 bands
Astrometric Data
Parallax
1.368 mas
Total Proper Motion
20.958 mas/yr
PM Right Ascension
-6.63 mas/yr
PM Declination
-19.88 mas/yr
Galactic Cartesian (pc)
x = 0.201 · y = -0.653 · z = 0.730
Equatorial (J2000)
RA 287.10103° · Dec 46.89640°
Galactic ℓ, b
77.568° · 16.735°
Ecliptic λ, β
303.049° · 68.382°
HTM-20 index
-1665530804
Similar Worlds
Kepler-314 c
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.90 R⊕ · 877.0 ly
Kepler-130 c
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.90 R⊕ · 1,032.8 ly
Kepler-1554 b
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.90 R⊕ · 3,088.2 ly
Kepler-600 b
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.90 R⊕ · 2,021.3 ly
Kepler-1447 b
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.90 R⊕ · 2,903.8 ly
Kepler-276 c
Sub-Neptune · G-type yellow (Sun-like)
Radius 2.90 R⊕ · 3,734.0 ly