Host star — Teegarden's Star
- Spectral type
- M7.0 V
- Temperature
- 3,034 K
- Radius
- 0.12 R☉
- Mass
- 0.10 M☉
- Luminosity
- 0.001 L☉
- Distance
- 3.8 pc (12.5 ly)
Red dwarf — the most common type of star. Cool and small.
Very cool — a faint red dwarf.
Teegarden's Star b
Orbits Teegarden's Star · 12.5 light-years from Earth
RockyRadial Velocity2019ESI 88 · Very Earth-like
Radius
1.05×
Earth
Mass
1.2×
Earth
Year
5d
Temp
277 K
4°C
Gravity
1.1×
Earth
Distance
12.5
ly
Could life exist here?
AI analysisTeegarden's Star b is a rocky world barely larger than Earth—just 1.05 Earth radii with a similar density—orbiting an ultracool red dwarf only 12.5 light-years away. Its equilibrium temperature of 277 Kelvin (4 degrees Celsius) places it near Earth's average, a genuinely promising sign for habitability. However, the planet circles its tiny host star every 4.91 days at just 0.0259 astronomical units, extremely close and likely causing tidal locking, where one hemisphere perpetually faces the star while the other freezes in darkness. The star itself is remarkably faint and dim, with a surface temperature of only 3,030 Kelvin. Whether liquid water could exist in a stable habitable zone on such a tidally locked world remains uncertain; models disagree on whether atmospheric circulation could redistribute heat from the day side to survival-enabling twilight zones or night side refugia. Despite these unknowns, Teegarden's Star b earned a habitability score of 88 out of 100, making it one of the most Earth-like exoplanets known. Its proximity and discovery via radial velocity—a method that reveals planetary mass directly—make it an exceptional target for future atmospheric studies that might constrain whether habitability is truly possible.
What it would be like
Teegarden's Star 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 1.1g — noticeably heavier what you're used to on Earth.
With an equilibrium temperature around 4°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 4.9 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.
Radius1.05R⊕
1/25×Earth = 125×
Mass1.16M⊕
1/10000×Earth = 110000×
Surface gravity1.05g
1/100×Earth = 1100×
Equilibrium temp277 K(4°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
- 2019
- Facility
- Calar Alto Observatory
- Semi-major axis
- 0.0259 AU
- Period
- 4.91 days
- Eccentricity
- 0.0300
- Density
- 5.51 g/cm³
Detected by the star's wobble — gravitational tug from the orbiting planet shifts spectral lines.
Mildly elliptical — similar to most Solar System planets.
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
Teegarden's StarTeegarden's Star bOrbitHabitable zone
Drag to rotate · scroll to zoomSemi-major axis: 0.026 AUEccentricity: 0.0300Period: 4.9 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 12.5 light-years?
- A light beam leaving Earth right now would arrive in 12.5 years.
- At Voyager 1's speed (17 km/s), the trip would take approximately 220,342 years.
- A radio signal sent today would arrive in 12.5 years — and the reply wouldn't come back for twice that.
Earth Similarity Index
88/1000 — 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.