Host star — GJ 3323
- Spectral type
- M4
- Temperature
- 3,159 K
- Radius
- 0.12 R☉
- Mass
- 0.16 M☉
- Luminosity
- 0.003 L☉
- Distance
- 5.4 pc (17.5 ly)
Red dwarf — the most common type of star. Cool and small.
Very cool — a faint red dwarf.
GJ 3323 b
Orbits GJ 3323 · 17.5 light-years from Earth
RockyRadial Velocity2017ESI 81 · Very Earth-like
Radius
1.23×
Earth
Mass
2.0×
Earth
Year
5d
Temp
290 K
17°C
Gravity
1.3×
Earth
Distance
17.5
ly
Could life exist here?
AI analysisGJ 3323 b orbits an M4 dwarf star just 17.5 light-years away, making it one of our nearest exoplanet neighbors. The planet is only 23 percent larger than Earth and roughly twice Earth's mass, giving it a density of 5.96 g/cm³—nearly identical to Earth's, suggesting a rocky composition with a substantial core. Its equilibrium temperature of 290 Kelvin sits just below Earth's mean surface temperature, positioning it in the habitable zone by many definitions. However, the planet completes an orbit in just 5.4 days at a hair-close 0.033 AU from its host star, and its modest eccentricity of 0.23 means it experiences significant heating variations. The extreme closeness to its small star almost certainly means the planet is tidally locked, with one face perpetually facing the star and the other frozen in darkness—a configuration that would redistribute water toward the terminator and complicate habitability. Despite these challenges, GJ 3323 b's temperate equilibrium temperature and Earth-like mass have earned it a habitability score of 81 out of 100. This nearby, radial-velocity-detected world deserves continued scrutiny as a prime target for future atmospheric characterization.
What it would be like
GJ 3323 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 1.3g — noticeably heavier what you're used to on Earth.
With an equilibrium temperature around 17°C, this planet sits in the temperature range where liquid water could potentially exist on the surface — a key ingredient for life as we know it.
A year here is only 5.4 Earth days. Seasons, if they exist, change in a matter of hours.
Earth comparison
Logarithmic bars so Jupiter-class planets fit the same scale as Earth-size worlds.
Radius1.23R⊕
1/25×Earth = 125×
Mass2.02M⊕
1/10000×Earth = 110000×
Surface gravity1.34g
1/100×Earth = 1100×
Equilibrium temp290 K(17°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
- 2017
- Facility
- La Silla Observatory
- Semi-major axis
- 0.0328 AU
- Period
- 5.36 days
- Eccentricity
- 0.2300
- Density
- 5.96 g/cm³
Detected by the star's wobble — gravitational tug from the orbiting planet shifts spectral lines.
Noticeably elliptical. Seasons (if any) would vary in intensity.
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
Orbital Animation
GJ 3323GJ 3323 bOrbitHabitable zone
Drag to rotate · scroll to zoomSemi-major axis: 0.033 AUEccentricity: 0.2300Period: 5.4 days
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 17.5 light-years?
- A light beam leaving Earth right now would arrive in 17.5 years.
- At Voyager 1's speed (17 km/s), the trip would take approximately 309,154 years.
- A radio signal sent today would arrive in 17.5 years — and the reply wouldn't come back for twice that.
Earth Similarity Index
81/1000 — 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.