Host star — TOI-2257
- Spectral type
- M3
- Temperature
- 3,430 K
- Radius
- 0.31 R☉
- Mass
- 0.33 M☉
- Luminosity
- 0.014 L☉
- Distance
- 57.8 pc (188 ly)
Red dwarf — the most common type of star. Cool and small.
Very cool — a faint red dwarf.
TOI-2257 b
Orbits TOI-2257 · 188 light-years from Earth
Super-EarthTransit2021ESI 87 · Very Earth-like
Radius
2.19×
Earth
Mass
5.5×
Earth
Year
35d
Temp
256 K
-17°C
Gravity
1.1×
Earth
Distance
188
ly
What it would be like
TOI-2257 b is a super-Earth — larger than our planet but likely still rocky or ice-rich. Whether it has a thin atmosphere like Mars or a crushing one like Venus remains unknown.
Surface gravity is about 1.1g — 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.
An orbital period of 35 days makes the year 10.4× 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.
Radius2.19R⊕
1/25×Earth = 125×
Mass5.45M⊕
1/10000×Earth = 110000×
Surface gravity1.13g
1/100×Earth = 1100×
Equilibrium temp256 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
- Transit
- Year
- 2021
- Facility
- Transiting Exoplanet Survey Satellite (TESS)
- Semi-major axis
- 0.1450 AU
- Period
- 35.19 days
- Eccentricity
- 0.4960
- Density
- 2.84 g/cm³
Detected by measuring the tiny dip in starlight as the planet crosses in front of its star.
Highly eccentric — temperatures would swing wildly between closest and farthest approach.
Low density — probably icy or gas-rich.
Discovered via · Transit
Tiny dip in starlight as the planet crosses in front of its star
A transit photometer watches a star nonstop and measures its brightness to ~0.01%. When a planet passes between us and the star, the star dims briefly — the deeper the dip, the bigger the planet. This is how Kepler and TESS found most known exoplanets.
- Overall share
- ~75% of all confirmed worlds
- Best for
- Earth-to-Neptune-sized planets on short orbits
Orbital Animation
TOI-2257TOI-2257 bOrbitHabitable zone
Drag to rotate · scroll to zoomSemi-major axis: 0.145 AUEccentricity: 0.4960Period: 35.2 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 188 light-years?
- A light beam leaving Earth right now would arrive in 188 years.
- At Voyager 1's speed (17 km/s), the trip would take approximately 3.3 million years.
- A radio signal sent today would arrive in 188.5 years — and the reply wouldn't come back for twice that.
Earth Similarity Index
87/1000 — 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.