Ross 508 b
Water WorldMarginal37 light years awayFound 2022
Ross 508 b, from the NASA Exoplanet Archive (found 2022). Measured: 4 Earth masses, 0.0537 AU, a 3071 K M-type star. Composition inferred from a measured bulk density of 0.65x Earth's — too light for bare rock, so a large fraction of water and ice, with a day locked to its 10.8-day year, as anything orbiting this close would be.
Ross 508
- Type
- M-type (Red Dwarf)
- Spectral type
- M4.5 V
- Temperature
- 3,071 K
- Radius
- 0.211 ☉
- Mass
- 0.177 ☉
- Known planets
- 1 (this one)
- Luminosity
- 3.59e-3 ☉
Published by the NASA Exoplanet Archive. This world’s temperature and habitability score are computed from this star’s measured luminosity, not from a stand-in for its class.
Water World
Life DetectedHigh Activity
Why is this a Water World?Your planet has abundant oxygen (41.2%) and hydrogen (17.6%), creating extensive water coverage while in the habitable temperature zone.
Water worlds have deep global oceans covering most or all of their surface. They form when planets have high water content and orbit in the habitable zone.
Classification Criteria:
✓ Oxygen: 41.2% + Hydrogen: 17.6% (water-forming elements)✓ Temperature: 316K (habitable range)✓ Distance: 0.05 AU (habitable zone)
Habitability ScoreMarginal
Contributing Factors
temperature70
Challenging but potentially habitable temperature
atmosphere60
Nitrogen-oxygen atmosphere - breathable and protective (partially stripped by slow rotation)
water100
Abundant water
magnetic Field30
No magnetic field - vulnerable to solar radiation
geology90
Active geology recycles nutrients and drives carbon cycle
Organic Chemistry80
Core organic elements (CHNO) present
rotation30
Very slow rotation - extreme temperature swings between eternal day and night sides
Physical Properties
Mass
4.00x Earth (2.39e+25 kg)Radius
1.59x Earth (10,113 km)Surface Gravity
1.59x Earth (15.6 m/s²)Surface Temperature
316 K (43 °C / 109 °F)Rotation Period
259.2 hours/day (slower than Earth)Orbital Environment
Star Type
M-type (Red Dwarf)Distance from Star
0.05 AU (8.03 million km)Orbital Period
8 daysAtmosphere
Nitrogen and oxygen with water vapor, mild greenhouse effect
Elemental Composition
O - Oxygen
41.2%
H - Hydrogen
17.6%
Si - Silicon
11.8%



