- weight
- ≥ 1.11 g
- sun
- 2.6× wider
- sky
- deep orange
Illustration computed from this world’s measured and derived values, not a photograph.
GJ 3998 d
GJ 3998 d is a confirmed sub-Neptune exoplanet 59.2 ly from Earth in the constellation Ophiuchus, discovered in 2025 by Multiple Observatories.
Radial Velocity: spotted by the gravitational wobble the planet tugs in its star.
Standing on GJ 3998 d, you would weigh roughly about 11% more than you do on Earth. Its orange dwarf looks 2.6× wider than ours, bathing the surface in deep 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 42 days, and at an estimated 19°C (66°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 · habitable zone
If your children grew up herea playful thought experiment
Gravity close to Earth's, at about 1.1 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 much as it does on Earth.
Assuming Earth-like air at this world's temperature of about 19°C (66°F), sound would travel close to its Earth speed, so your voice would sound much as it does on Earth. The real atmosphere is unknown.
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.
- Surface temperatures near 19°C (66°F) fall in the range where liquid water is at least possible.
- Surface gravity is close to Earth's, at least 1.11 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 3998 d’s measured and computed values, not a real advisory.
How long to get there · 59.2 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 GJ 3998 d?
GJ 3998 d's surface gravity is at least 1.1 times Earth's, and possibly more: its mass is only a lower bound.
How much would you weigh on GJ 3998 d?
Someone who weighs 150 pounds on Earth would weigh at least 166 pounds on GJ 3998 d.
How far is GJ 3998 d from Earth?
GJ 3998 d lies about 59.2 light-years from Earth.
How long would it take to get to GJ 3998 d?
At the speed of NASA's Parker Solar Probe, the fastest craft ever built, the journey would take about 92,304 years.
How hot is GJ 3998 d?
GJ 3998 d's equilibrium temperature, the balance it reaches from its star's light alone before any greenhouse warming, is about 19°C (66°F).
Is GJ 3998 d habitable?
GJ 3998 d orbits near its star's habitable zone, the range of distances where liquid water could be stable, and its Earth-similarity index is 0.71. That makes it worth studying, but it is not evidence of life: we have no measurement of its atmosphere, water, or surface.
How long is a year on GJ 3998 d?
GJ 3998 d completes one orbit of its star in 42 days.
Illustration generated from GJ 3998 d's confirmed parameters, not a photograph.