- weight
- ≥ 1.00 g
- sun
- 4.1× wider
- sky
- amber-orange
Illustration computed from this world’s measured and derived values, not a photograph.
GJ 338 B b
GJ 338 B b is a confirmed sub-Neptune exoplanet 20.7 ly from Earth in the constellation Ursa Major, discovered in 2020 by Calar Alto Observatory.
Radial Velocity: spotted by the gravitational wobble the planet tugs in its star.
Standing on GJ 338 B b, you would weigh roughly almost exactly what you weigh on Earth. Its orange dwarf looks 4.1× wider than ours, bathing the surface in amber-orange 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 24 days, and at an estimated 118°C (244°F) it is warm.
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 about 1.0 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 noticeably higher and reedier.
Assuming Earth-like air at this world's temperature of about 118°C (244°F), sound would travel roughly 17% faster than on Earth, so your voice would sound noticeably higher and reedier. 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.
- !Persistently hot at around 118°C (244°F), well above anything you would call comfortable.
- Surface gravity is close to Earth's, at least 1.00 times, so you would move much as you do here.
- !Likely tidally locked: one hemisphere in endless day, the other in permanent night.
A playful read of GJ 338 B b’s measured and computed values, not a real advisory.
How long to get there · 20.7 ly away
No other confirmed planets here yet. New ones auto-appear as telescopes report.
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 GJ 338 B b?
GJ 338 B b's surface gravity is at least 1.0 times Earth's, and possibly more: its mass is only a lower bound.
How much would you weigh on GJ 338 B b?
Someone who weighs 150 pounds on Earth would weigh at least 151 pounds on GJ 338 B b.
How far is GJ 338 B b from Earth?
GJ 338 B b lies about 20.7 light-years from Earth.
How long would it take to get to GJ 338 B b?
At the speed of NASA's Parker Solar Probe, the fastest craft ever built, the journey would take about 32,212 years.
How hot is GJ 338 B b?
GJ 338 B b's equilibrium temperature, the balance it reaches from its star's light alone before any greenhouse warming, is about 118°C (244°F).
How long is a year on GJ 338 B b?
GJ 338 B b completes one orbit of its star in 24 days.
Illustration generated from GJ 338 B b's confirmed parameters, not a photograph.