Host star — GJ 1002
- Spectral type
- M5.5 V
- Temperature
- 3,024 K
- Radius
- 0.14 R☉
- Mass
- 0.12 M☉
- Luminosity
- 0.001 L☉
- Distance
- 4.8 pc (15.8 ly)
Red dwarf — the most common type of star. Cool and small.
Very cool — a faint red dwarf.
GJ 1002 b
Orbits GJ 1002 · 15.8 light-years from Earth
RockyRadial Velocity2022ESI 86 · Very Earth-like
Radius
1.03×
Earth
Mass
1.1×
Earth
Year
10d
Temp
231 K
-42°C
Gravity
1.0×
Earth
Distance
15.8
ly
Could life exist here?
AI analysisGJ 1002 b is an Earth-sized rocky world just 15.8 light-years away, orbiting a dim red dwarf star every 10.3 days at a distance of 0.0457 AU. With a radius of 1.03 Earth radii and a mass of 1.08 Earth masses, it is genuinely Earth-like in bulk properties and likely has a solid surface. However, its equilibrium temperature of 231 Kelvin—roughly minus 42 degrees Celsius—makes it far colder than Earth, sitting in the frozen outer edge of the habitable zone where liquid water could exist only in unusual circumstances or if the planet retains substantial internal heat. The planet's proximity to its faint host star means it is almost certainly tidally locked, with one face perpetually baked and the other in eternal darkness, complicating habitability further. Despite these challenges, GJ 1002 b's high habitability score of 86 reflects its genuine Earth-like composition and the possibility that atmospheric circulation or subsurface heat could create pockets of habitability. What makes this world especially compelling is that it was discovered by radial velocity—a technique that reveals mass directly—meaning we know it is genuinely rocky, not a misleading gas dwarf.
What it would be like
GJ 1002 b is a rocky world, potentially similar in composition to Earth or Mars — a solid surface you could, in theory, stand on.
Surface gravity is about 1.0g — almost identical to what you're used to on Earth.
At -42°C, this world is cold — similar to Earth's polar regions or the surface of Mars. Water would likely be frozen, but subsurface liquid isn't ruled out.
An orbital period of 10 days makes the year 35.3× shorter than Earth's. You'd celebrate your birthday more often here.
Earth comparison
Logarithmic bars so Jupiter-class planets fit the same scale as Earth-size worlds.
Radius1.03R⊕
1/25×Earth = 125×
Mass1.08M⊕
1/10000×Earth = 110000×
Surface gravity1.02g
1/100×Earth = 1100×
Equilibrium temp231 K(-42°C)
0 KEarth 255 K2500 K
Side-by-side with Earth
Temperature in context
Liquid N₂Mars avgEarth eq.Earth sfc.Boiling H₂OVenus
Discovery & orbit
- Method
- Radial Velocity
- Year
- 2022
- Facility
- Multiple Observatories
- Semi-major axis
- 0.0457 AU
- Period
- 10.35 days
- Eccentricity
- —
- Density
- 5.43 g/cm³
Detected by the star's wobble — gravitational tug from the orbiting planet shifts spectral lines.
Rocky composition likely. Earth is 5.51 g/cm³.
Discovered via · Radial velocity
The star's wobble — gravitational tug from the planet shifts its spectrum
A planet orbiting a star pulls it slightly back and forth. That motion compresses the star's light when moving toward us (blueshift) and stretches it away (redshift). Precision spectrographs detect the wobble at metres-per-second — enough to infer a planet's mass and orbit.
- Overall share
- ~19% of discoveries
- Best for
- Massive, close-in planets around nearby bright stars
Hertzsprung–Russell Diagram
Where this host star sits among … exoplanet host stars. The main sequence band runs diagonally — giants and supergiants sit above, white dwarfs below.
OBAFGKMCurrent star
How far is 15.8 light-years?
- A light beam leaving Earth right now would arrive in 15.8 years.
- At Voyager 1's speed (17 km/s), the trip would take approximately 278,889 years.
- A radio signal sent today would arrive in 15.8 years — and the reply wouldn't come back for twice that.
Earth Similarity Index
86/1000 — Nothing like Earth100 — Identical to Earth
ESI combines radius similarity and equilibrium temperature similarity. Earth = 100. Mars ≈ 73. Venus ≈ 44. This score reflects two physical parameters only — not atmosphere, water, or magnetic field.