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Entering orbit…
Habitability
82/ 100
Highly Habitable
Kepler-438 b rendered in TerraForge from its measured mass, orbit and star

Kepler-438 b

Also written Kepler-438b, Kepler 438b, Kepler 438 b

Earth Like639 light years awayFound 2015
Mass
1.46 × Earth
Radius
1.12 × Earth
Gravity
1.16 g
Surface (est.)
318 K
Year
35.2 days
From Earth
639 ly
Mass
1.46 × Earth
Radius
1.12 × Earth
Gravity
1.16 g
Surface (est.)
318 K
Year
35.2 days
From Earth
639 ly

Kepler-438 system

Type
K-type (Orange)
Temperature
3,748 K
Radius
0.52 ☉
Mass
0.544 ☉
Planets
1
Luminosity
0.0440 ☉

Published by the NASA Exoplanet Archive. This world’s temperature and habitability score are computed from this star’s measured luminosity, not from a stand-in for its class.

Kepler-438 b0.17 AUYou are here1.5 M⊕
Habitable zone

Star and planets drawn to scale: the star is 51 times as wide as Kepler-438 b, so only its edge is in view. Orbits spaced as in the star system view.

Kepler-438 b was announced in 2015 as one of the two planets most similar to Earth found to that date, judging by its size and the light it receives. It is about 1.1 times Earth's width and orbits a red dwarf about 640 light-years away every 35.2 days, receiving about 1.4 times the light Earth gets from the Sun.

Surface. Rocky surface with continents, oceans, and active plate tectonics. Diverse biomes if life present.

✓ Conditions could support life. This planet’s modelled conditions could support biological processes: stable temperatures, liquid water and the chemistry life as we know it needs. That makes life possible, not present.

Earth Like
Life possibleMagnetic FieldModerate Activity
Kepler-438 b has a balanced composition with all CHNOPS elements, proper mass (1.5x Earth), and sits in the habitable zone at 0.17 AU.
Earth-like planets have the perfect combination of composition, temperature, mass, and magnetic field to potentially support complex life as we know it.
Classification Criteria:
✓ All CHNOPS elements present (C, H, N, O, P, S)✓ Mass: 1.5x Earth (0.5-2.0x range)✓ Temperature: 318K (250-320K range)✓ Magnetic field present✓ Distance: 0.17 AU (habitable zone)

Reading Kepler-438 b’s atmosphere

Dominant elements: O, Si, Fe, N, H, CThis is what a telescope would measure while Kepler-438 b crosses in front of its star: starlight passes through the atmosphere and spreads into a rainbow band. Each dark line marks a wavelength the atmosphere absorbed.Every element absorbs its own signature wavelengths — hydrogen always darkens the same two spots, calcium another pair, and so on. Astronomers match the lines in a real spectrum against a library of these signatures to say what an atmosphere is made of, light-years away, without ever visiting. A deeper line generally means more of that element is present.Kepler-438 b sits about 639 light-years away, found by the transit method. Most catalogued distances trace back to parallax: as Earth orbits the Sun, a nearby star appears to shift very slightly against the distant background stars, and the size of that shift gives its distance directly.
Further reading
ExoplanetsSara Seager (editor)The field's standard reference: how planets are found, how they form, and what their atmospheres are made of.The Planet FactoryElizabeth TaskerHow planets are made, and why so few of them come out like Earth.The Little Book of ExoplanetsJoshua WinnHow these worlds are found, and what a measurement can honestly tell us.Envisioning ExoplanetsMichael CarrollWhat these worlds might look like from the ground, painted from the same measurements this page renders.
As an Amazon Associate I earn from qualifying purchases — if you buy through these links, TerraForge may receive a small commission at no extra cost to you.
Habitability ScoreHighly Habitable
82
Contributing Factors
temperature84
Warm - livable, but heat stress grows with every degree
atmosphere100

Nitrogen-oxygen atmosphere with trace CO₂, water vapor, and argon

Nitrogen-oxygen atmosphere - breathable and protective
water50
Limited water content
magnetic Field100
Magnetic field provides radiation protection
geology90
Active geology recycles nutrients and drives carbon cycle
Organic Chemistry80
Core organic elements (CHNO) present
rotation100
Optimal rotation period - balanced day/night cycle, moderate weather, and good heat distribution

Physical Properties

Mass
1.46x Earth (8.72e+24 kg)
Radius
1.13x Earth (7,228 km)
This planet: 1.13× Earth radiusEarth: 1× (baseline)
Surface Gravity
1.13x Earth (11.1 m/s²)
Surface Temperature
318 K (45 °C / 112 °F)
Rotation Period
24.0 hours/day
This planet: 24 h/dayEarth: 24 h/day

Elemental Composition

How TerraForge built this world

Kepler-438 b, from the NASA Exoplanet Archive (found 2015). Measured: 1.46 Earth masses, 0.166 AU, a 3748 K K-type star. Composition inferred from a measured bulk density of 1.04x Earth's, which is rock and iron, with an assumed 24-hour day — rotation cannot be measured for exoplanets.

A dark ringed planet hanging over the horizon of a rocky moon, its rings lit by a distant sun

New: Stand on Your Moons 🌒

A planet's surface view isn't the only ground any more. Press the surface button on a planet with moons and it asks where to stand: the planet itself, or any moon still in orbit, each tagged with what it became — ocean, ice, carbon, volcanic. Every moon gets its own ground and sky from its own physics: airless rock under a black sky, ice cracked by geysers over a hidden sea, sulfur plains shaking with eruptions, or orange haze you can't see the sun through. And hanging over the horizon, there's the planet you built.

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