- weight
- 1.19 g
- sun
- 19.3× wider
- sky
- warm white
Illustration computed from this world’s measured and derived values, not a photograph.
K2-138 c
K2-138 c is a confirmed sub-Neptune exoplanet 661 ly from Earth in the constellation Aquarius, discovered in 2017 by K2.
Transit: spotted by the tiny, repeating dip in its star’s light each time the planet crosses in front of it.
Standing on K2-138 c, you would weigh about 19% more than you do on Earth. Its yellow, Sun-like star looks 19.3× wider than ours, bathing the surface in warm white light. It is likely tidally locked, so that sun never moves in the sky: one hemisphere in endless day, the other in permanent night. A year passes in just 3.6 days, and at an estimated 739°C (1362°F) it is furnace-hot.
How closely this world matches Earth in size and warmth, from 0 to 1 (Earth = 1.0). Computed by gravityfinder. See every world ranked →
What these mean: surface gravity · tidal locking · equilibrium temperature · Earth similarity
If your children grew up herea playful thought experiment
Gravity close to Earth's, at 1.2 times. A child would grow up much as they would back home.
A playful thought experiment from this world’s gravity, not a prediction about any real person. No human has ever grown up off Earth, so no one truly knows; the direction (taller in low gravity, shorter and stockier in high) follows how growing bodies respond to weight.
Hear how a voice sounds herea computed acoustic demo
Your voice would sound high and thin, almost cartoonish.
Assuming Earth-like air at this world's temperature of about 739°C (1362°F), sound would travel roughly 87% faster than on Earth, so your voice would sound high and thin, almost cartoonish. The real atmosphere is unknown, so this is a best guess.
A real voice sample, pitch-shifted (tempo held constant) to suggest the acoustics: a playful approximation, not a precise simulation. Voice: Lingua Libre / Vealhurl, CC BY-SA 4.0.
- !Furnace-hot at around 739°C (1362°F), with no liquid water and no shade anywhere.
- Surface gravity is close to Earth's, 1.19 times, so you would move much as you do here.
- !Its star delivers about 279 times the sunlight Earth gets, a blinding, sterilizing glare.
- !Likely tidally locked: one hemisphere in endless day, the other in permanent night.
A playful read of K2-138 c’s measured and computed values, not a real advisory.
How long to get there · 661 ly away
Zoom out: star → system → (soon) galaxy arm, host black hole, and a real image of the host galaxy.
Matched telescope & eyepiece recommendations are coming. Any product links will carry a clear affiliate disclosure.
What is the gravity on K2-138 c?
K2-138 c's surface gravity is about 1.2 times Earth's.
How much would you weigh on K2-138 c?
Someone who weighs 150 pounds on Earth would weigh about 179 pounds on K2-138 c.
How far is K2-138 c from Earth?
K2-138 c lies about 661 light-years from Earth.
How long would it take to get to K2-138 c?
At the speed of NASA's Parker Solar Probe, the fastest craft ever built, the journey would take about 1.0 million years.
How hot is K2-138 c?
K2-138 c's equilibrium temperature, the balance it reaches from its star's light alone before any greenhouse warming, is about 739°C (1362°F).
How long is a year on K2-138 c?
K2-138 c completes one orbit of its star in 3.6 days.
Illustration generated from K2-138 c's confirmed parameters, not a photograph.