- weight
- 0.18 g
- sun
- 0.19× as wide
- sky
- warm white
Illustration computed from this world’s measured and derived values, not a photograph.
Io
Io is a rocky world in our own solar system.
Standing on Io, you would weigh about 82% less than you do on Earth. From here the Sun looks 0.19× as wide as it does from Earth, bathing the surface in warm white light. A year here lasts 11.9 Earth years, and at an estimated -163°C (-262°F) it is colder than almost anywhere in the solar system.
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
Low gravity, 0.18 times Earth's. A child who grew up here could become strikingly tall and lightly built, about 1.4x taller than on Earth: a 5 ft 10 in adult could stand nearer 8 ft 2 in, with long limbs and slender bones.
- 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.
- Heart
- Unhurried
- With less weight pulling blood down toward the feet, the heart has far less work to do.
- 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
You would hear nothing at all.
With essentially no atmosphere, there is no medium to carry sound. You could shout into someone's helmet from an inch away and they would hear nothing: space is silent.
- !The most volcanically active world in the solar system, its surface repaved by constant eruptions.
- !It sits deep inside Jupiter's radiation belts, which would be lethal within hours.
- !Only a wisp of sulfur-dioxide gas, nothing you could breathe.
A playful read of Io’s measured and computed values, not a real advisory.
Io is in our own solar system. It orbits about 5.20 AU from the Sun, so sunlight reaches it in roughly 43 minutes. From Earth it is about 4.20 AU away at closest, and a spacecraft is far slower:
How long to get there with today’s craft
At the speed of the Parker Solar Probe, the fastest craft ever built, the trip to Io would take about 38 days; a real mission took the Juno probe just under 5 years to reach Jupiter's neighborhood.
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 Io?
Io's surface gravity is about 0.18 times Earth's.
How much would you weigh on Io?
Someone who weighs 150 pounds on Earth would weigh about 27 pounds on Io.
How hot is Io?
Io's equilibrium temperature, the balance it reaches from its star's light alone before any greenhouse warming, is about -163°C (-262°F).
How long is a year on Io?
Io completes one orbit of the Sun in 11.9 years.
The portrait of Io is a real photograph (NASA/JPL/University of Arizona, Public domain). The "stand here" scene and the size comparison are computed illustrations, not photographs.