- weight
- 0.48 g
- sun
- 9.4× wider
- sky
- warm white
Illustration computed from this world’s measured and derived values, not a photograph.
Kepler-221 d
Kepler-221 d is a confirmed sub-Neptune exoplanet 1,256 ly from Earth in the constellation Cygnus, discovered in 2014 by Kepler.
Transit: spotted by the tiny, repeating dip in its star’s light each time the planet crosses in front of it.
Standing on Kepler-221 d, you would weigh about 52% less than you do on Earth. Its yellow, Sun-like star looks 9.4× 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 10 days, and at an estimated 439°C (822°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
Lighter than home, at 0.48 times Earth's gravity. A child raised here would likely grow taller and more slender than their Earth-raised parents, about 1.2x taller than on Earth: a 5 ft 10 in adult could stand nearer 6 ft 9 in.
- Bones
- Light and slender
- With little weight to carry, the growing skeleton lays down far less bone, the way astronauts' bones thin in months of low gravity.
- Movement
- Bounding and springy
- So little weight means each step would carry the body up and forward in long, floating strides.
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 439°C (822°F), sound would travel roughly 57% 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 439°C (822°F), with no liquid water and no shade anywhere.
- !Low gravity, 0.48 times Earth's, would hold only a thin, unbreathable atmosphere at best.
- !Its star delivers about 56 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 Kepler-221 d’s measured and computed values, not a real advisory.
How long to get there · 1,256 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 Kepler-221 d?
Kepler-221 d's surface gravity is about 0.48 times Earth's.
How much would you weigh on Kepler-221 d?
Someone who weighs 150 pounds on Earth would weigh about 73 pounds on Kepler-221 d.
How far is Kepler-221 d from Earth?
Kepler-221 d lies about 1,256 light-years from Earth.
How long would it take to get to Kepler-221 d?
At the speed of NASA's Parker Solar Probe, the fastest craft ever built, the journey would take about 2.0 million years.
How hot is Kepler-221 d?
Kepler-221 d's equilibrium temperature, the balance it reaches from its star's light alone before any greenhouse warming, is about 439°C (822°F).
How long is a year on Kepler-221 d?
Kepler-221 d completes one orbit of its star in 10 days.
Illustration generated from Kepler-221 d's confirmed parameters, not a photograph.