- weight
- 0.86 g
- sun
- 10.5× wider
- sky
- bright white
Illustration computed from this world’s measured and derived values, not a photograph.
HD 28109 b
HD 28109 b is a confirmed sub-Neptune exoplanet 455 ly from Earth in the constellation Hydrus, discovered in 2022 by Transiting Exoplanet Survey Satellite (TESS).
Transit: spotted by the tiny, repeating dip in its star’s light each time the planet crosses in front of it.
Standing on HD 28109 b, you would weigh about 14% less than you do on Earth. Its yellow-white star looks 10.5× wider than ours, bathing the surface in bright 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 23 days, and at an estimated 594°C (1101°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 0.86 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 594°C (1101°F), sound would travel roughly 74% 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 594°C (1101°F), with no liquid water and no shade anywhere.
- Surface gravity is close to Earth's, 0.86 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 HD 28109 b’s measured and computed values, not a real advisory.
How long to get there · 455 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 HD 28109 b?
HD 28109 b's surface gravity is about 0.86 times Earth's.
How much would you weigh on HD 28109 b?
Someone who weighs 150 pounds on Earth would weigh about 129 pounds on HD 28109 b.
How far is HD 28109 b from Earth?
HD 28109 b lies about 455 light-years from Earth.
How long would it take to get to HD 28109 b?
At the speed of NASA's Parker Solar Probe, the fastest craft ever built, the journey would take about 710,167 years.
How hot is HD 28109 b?
HD 28109 b's equilibrium temperature, the balance it reaches from its star's light alone before any greenhouse warming, is about 594°C (1101°F).
How long is a year on HD 28109 b?
HD 28109 b completes one orbit of its star in 23 days.
Illustration generated from HD 28109 b's confirmed parameters, not a photograph.