Host star — Kepler-438
- Spectral type
- —
- Temperature
- 3,748 K
- Radius
- 0.52 R☉
- Mass
- 0.54 M☉
- Luminosity
- 0.044 L☉
- Distance
- 195.9 pc (639 ly)
Cooler than the Sun. Orange or red dwarf.
Kepler-438 b
Orbits Kepler-438 · 639 light-years from Earth
RockyTransit2015ESI 83 · Very Earth-like
Radius
1.12×
Earth
Mass
1.5×
Earth
Year
35d
Temp
288 K
15°C
Gravity
1.2×
Earth
Distance
639
ly
What it would be like
Kepler-438 b is a rocky world, potentially similar in composition to Earth or Mars — a solid surface you could, in theory, stand on.
Surface gravity is about 1.2g — noticeably heavier what you're used to on Earth.
With an equilibrium temperature around 15°C, this planet sits in the temperature range where liquid water could potentially exist on the surface — a key ingredient for life as we know it.
An orbital period of 35 days makes the year 10.4× shorter than Earth's. You'd celebrate your birthday more often here.
Earth comparison
Logarithmic bars so Jupiter-class planets fit the same scale as Earth-size worlds.
Radius1.12R⊕
1/25×Earth = 125×
Mass1.46M⊕
1/10000×Earth = 110000×
Surface gravity1.16g
1/100×Earth = 1100×
Equilibrium temp288 K(15°C)
0 KEarth 255 K2500 K
Side-by-side with Earth
Temperature in context
Liquid N₂Mars avgEarth eq.Earth sfc.Boiling H₂OVenus
Discovery & orbit
- Method
- Transit
- Year
- 2015
- Facility
- Kepler
- Semi-major axis
- 0.1660 AU
- Period
- 35.23 days
- Eccentricity
- 0.0300
- Density
- 5.71 g/cm³
Detected by measuring the tiny dip in starlight as the planet crosses in front of its star.
Mildly elliptical — similar to most Solar System planets.
Rocky composition likely. Earth is 5.51 g/cm³.
Discovered via · Transit
Tiny dip in starlight as the planet crosses in front of its star
A transit photometer watches a star nonstop and measures its brightness to ~0.01%. When a planet passes between us and the star, the star dims briefly — the deeper the dip, the bigger the planet. This is how Kepler and TESS found most known exoplanets.
- Overall share
- ~75% of all confirmed worlds
- Best for
- Earth-to-Neptune-sized planets on short orbits
Orbital Animation
Kepler-438Kepler-438 bOrbitHabitable zone
Drag to rotate · scroll to zoomSemi-major axis: 0.166 AUEccentricity: 0.0300Period: 35.2 days
Hertzsprung–Russell Diagram
Where this host star sits among … exoplanet host stars. The main sequence band runs diagonally — giants and supergiants sit above, white dwarfs below.
OBAFGKMCurrent star
How far is 639 light-years?
- A light beam leaving Earth right now would arrive in 639 years.
- At Voyager 1's speed (17 km/s), the trip would take approximately 11.3 million years.
- A radio signal sent today would arrive in 639.1 years — and the reply wouldn't come back for twice that.
Earth Similarity Index
83/1000 — Nothing like Earth100 — Identical to Earth
ESI combines radius similarity and equilibrium temperature similarity. Earth = 100. Mars ≈ 73. Venus ≈ 44. This score reflects two physical parameters only — not atmosphere, water, or magnetic field.