Interactive lab
Habitable Zone Explorer
Could another world support liquid water? Find promising real planets, experiment with the factors that shape their conditions, then investigate what observations reveal and what remains unknown.
What makes a planet potentially habitable?
Life as we know it needs liquid water. A star’s habitable zone is where a suitable atmosphere could sustain surface water, farther from brighter stars and closer to dimmer ones. Atmosphere, pressure, composition, stellar activity, and water retention also matter. Small size and Earth-like starlight suggest promising targets, but do not confirm rocky surfaces, water, or life. NASA: Understanding the habitable zone ↗
Explore real planets worth a closer look
This site’s simplified starting screen looks for small worlds receiving broadly Earth-like starlight: radius 0.5–1.8 times Earth’s and starlight 0.35–1.7 times Earth’s. These classroom defaults help identify worlds worth studying; passing the screen does not establish habitability. Adjust the ranges or search for a particular planet or star.
Radius and starlight are relative to Earth = 1.
Displaying 42 planets
42 of 42 matching planets have catalog values for both axes. Missing measurements are omitted; starlight inferred from temperature is used for filtering only. Logarithmic axes use equal spacing for multiplication (1 → 10 → 100). Star types are approximate temperature groups, using the same categories as Planet Playground.
All matches appear below; scroll sideways for more columns. Earth = 1 for radius, mass, and starlight. AU is Earth’s orbital distance; pc measures distance from us. “Estimated” starlight is inferred from catalog equilibrium temperature under Earth-like reflectivity assumptions. Missing values are unknown. Catalog filters are independent of the simulator.
| Planet / host star | Radius (Earth = 1) | Mass (Earth = 1) | Starlight (Earth = 1) | Equilibrium temperature | Year length (days) | Orbit (AU) | Distance from us (pc) | Host temperature (K) | Discovery | Investigate |
|---|---|---|---|---|---|---|---|---|---|---|
| Teegarden's Star b Teegarden's Star | 1.05 | Unknown | 1.08 | 4 °C (277 K) | 4.91 | 0.026 | 3.83 | 3,034 | Radial Velocity2019 | View habitability →NASA Archive ↗ |
| TOI-700 d TOI-700 | 1.15 | Unknown | 0.85 | -4 °C (269 K) | 37.42 | 0.164 | 31.13 | 3,459 | Transit2020 | View habitability →NASA Archive ↗ |
| Kepler-1649 c Kepler-1649 | 1.06 | Unknown | 0.75 | -39 °C (234 K) | 19.54 | 0.065 | 92.19 | 3,240 | Transit2020 | View habitability →NASA Archive ↗ |
| TRAPPIST-1 d TRAPPIST-1 | 0.79 | 0.39 | 1.12 | 13 °C (286 K) | 4.05 | 0.022 | 12.43 | 2,566 | Transit2016 | View habitability →NASA Archive ↗ |
| TOI-700 e TOI-700 | 0.92 | Unknown | 1.27 | 0 °C (273 K) | 27.81 | 0.134 | 31.13 | 3,459 | Transit2023 | View habitability →NASA Archive ↗ |
| GJ 1002 b GJ 1002 | 1.03 | Unknown | 0.67 | -42 °C (231 K) | 10.35 | 0.046 | 4.85 | 3,024 | Radial Velocity2022 | View habitability →NASA Archive ↗ |
| Proxima Cen b Proxima Cen | 1.02 | Unknown | 0.64 | -55 °C (218 K) | 11.18 | 0.048 | 1.3 | 2,900 | Radial Velocity2016 | View habitability →NASA Archive ↗ |
| GJ 3378 b GJ 3378 | 1.32 | Unknown | 0.91 | -1 °C (272 K) | 21.45 | 0.097 | 7.72 | 3,340 | Radial Velocity2026 | View habitability →NASA Archive ↗ |
| Wolf 1069 b Wolf 1069 | 1.08 | Unknown | 0.65 | -23 °C (250 K) | 15.56 | 0.067 | 9.58 | 3,158 | Radial Velocity2023 | View habitability →NASA Archive ↗ |
| TRAPPIST-1 e TRAPPIST-1 | 0.92 | 0.69 | 0.65 | -23 °C (250 K) | 6.1 | 0.029 | 12.43 | 2,566 | Transit2017 | View habitability →NASA Archive ↗ |
| LP 890-9 c LP 890-9 | 1.37 | 25.3 | 0.91 | -1 °C (272 K) | 8.46 | 0.04 | 32.43 | 2,850 | Transit2022 | View habitability →NASA Archive ↗ |
| K2-72 e K2-72 | 1.29 | Unknown | 1.2 | 13 °C (286 K) | 24.16 | 0.106 | 66.43 | 3,360 | Transit2016 | View habitability →NASA Archive ↗ |
| Ross 128 b Ross 128 | 1.11 | Unknown | 1.38 | 28 °C (301 K) | 9.87 | 0.05 | 3.37 | 3,192 | Radial Velocity2017 | View habitability →NASA Archive ↗ |
| Kepler-438 b Kepler-438 | 1.12 | Unknown | 1.4 | 15 °C (288 K) | 35.23 | 0.166 | 195.94 | 3,748 | Transit2015 | View habitability →NASA Archive ↗ |
| GJ 1061 d GJ 1061 | 1.16 | 1.67 | 0.6 | -31 °C (242 K) | 13.07 | 0.054 | 3.67 | 2,953 | Radial Velocity2020 | View habitability →NASA Archive ↗ |
| GJ 273 b GJ 273 | 1.51 | Unknown | 1.06 | 19 °C (292 K) | 18.65 | 0.091 | 5.92 | 3,382 | Radial Velocity2017 | View habitability →NASA Archive ↗ |
| L 98-59 f L 98-59 | 1.48 | Unknown | 1.1 | 12 °C (285 K) | 23.06 | 0.105 | 10.62 | 3,415 | Radial Velocity2025 | View habitability →NASA Archive ↗ |
| GJ 1061 c GJ 1061 | 1.19 | 1.81 | 1.4 | 31 °C (304 K) | 6.68 | 0.034 | 3.67 | 2,953 | Radial Velocity2020 | View habitability →NASA Archive ↗ |
| Teegarden's Star c Teegarden's Star | 1.02 | Unknown | 0.35 | -64 °C (209 K) | 11.42 | 0.046 | 3.83 | 3,034 | Radial Velocity2019 | View habitability →NASA Archive ↗ |
| TRAPPIST-1 f TRAPPIST-1 | 1.05 | 1.04 | 0.37 | -55 °C (218 K) | 9.21 | 0.038 | 12.43 | 2,566 | Transit2017 | View habitability →NASA Archive ↗ |
| Kepler-442 b Kepler-442 | 1.34 | Unknown | 0.66 | -32 °C (241 K) | 112.31 | 0.409 | 365.97 | 4,402 | Transit2015 | View habitability →NASA Archive ↗ |
| Gliese 12 b Gliese 12 | 0.93 | 0.95 | 1.62 | 41 °C (315 K) | 12.76 | 0.067 | 12.21 | 3,328 | Transit2024 | View habitability →NASA Archive ↗ |
| Kepler-452 b Kepler-452 | 1.63 | Unknown | 1.1 | -8 °C (265 K) | 384.84 | 1.046 | 551.73 | 5,757 | Transit2015 | View habitability →NASA Archive ↗ |
| Kepler-1512 b Kepler-1512 | 1.18 | Unknown | 1.6 | 49 °C (322 K) | 20.36 | 0.137 | 162 | 4,372 | Transit2016 | View habitability →NASA Archive ↗ |
| Kepler-1652 b Kepler-1652 | 1.6 | Unknown | 0.81 | -5 °C (268 K) | 38.1 | 0.165 | 252 | 3,638 | Transit2017 | View habitability →NASA Archive ↗ |
| Kepler-1410 b Kepler-1410 | 1.78 | Unknown | 1.06 | 17 °C (290 K) | 60.87 | 0.254 | 367 | 4,092 | Transit2016 | View habitability →NASA Archive ↗ |
| Kepler-1229 b Kepler-1229 | 1.4 | Unknown | 0.52 | -61 °C (212 K) | 86.83 | 0.301 | 265.48 | 3,784 | Transit2016 | View habitability →NASA Archive ↗ |
| TOI-715 b TOI-715 | 1.55 | Unknown | 0.67 | -39 °C (234 K) | 19.29 | 0.083 | 42.4 | 3,075 | Transit2023 | View habitability →NASA Archive ↗ |
| GJ 667 C f GJ 667 C | 1.45 | Unknown | 0.56 | Unknown | 39.03 | 0.156 | 7.24 | 3,350 | Radial Velocity2013 | View habitability →NASA Archive ↗ |
| GJ 667 C c GJ 667 C | 1.77 | Unknown | 0.88 | Unknown | 28.14 | 0.125 | 7.24 | 3,350 | Radial Velocity2013 | View habitability →NASA Archive ↗ |
| K2-3 d K2-3 | 1.46 | 2.2 | 1.44 | 32 °C (305 K) | 44.56 | 0.201 | 44.07 | 3,844 | Transit2015 | View habitability →NASA Archive ↗ |
| Kepler-62 f Kepler-62 | 1.41 | 35 | 0.5 | -65 °C (208 K) | 267.29 | 0.718 | 300.87 | 4,925 | Transit2013 | View habitability →NASA Archive ↗ |
| Kepler-296 e Kepler-296 | 1.53 | Unknown | 1.41 | 64 °C (337 K) | 34.14 | 0.169 | 167 | 3,740 | Transit2014 | View habitability →NASA Archive ↗ |
| Kepler-1544 b Kepler-1544 | 1.78 | Unknown | 0.83 | -4 °C (269 K) | 168.81 | 0.545 | 335.09 | 4,886 | Transit2016 | View habitability →NASA Archive ↗ |
| Wolf 1061 c Wolf 1061 | 1.66 | Unknown | 1.3 | 26 °C (299 K) | 17.87 | 0.089 | 4.31 | 3,342 | Radial Velocity2015 | View habitability →NASA Archive ↗ |
| Kepler-62 e Kepler-62 | 1.61 | 36 | 1.35 | -3 °C (270 K) | 122.39 | 0.427 | 300.87 | 4,925 | Transit2013 | View habitability →NASA Archive ↗ |
| TOI-1266 d TOI-1266 | 1.74 | 3.68 | 1.3 | 15 °C (288 K) | 32.51 | 0.151 | 36.01 | 3,563 | Transit Timing Variations2025 | View habitability →NASA Archive ↗ |
| Kepler-296 f Kepler-296 | 1.8 | Unknown | 0.62 | 1 °C (274 K) | 63.34 | 0.255 | 167 | 3,740 | Transit2014 | View habitability →NASA Archive ↗ |
| Gl 725 B c Gl 725 B | 1.66 | Unknown | 0.47 | -58 °C (215 K) | 37.9 | 0.139 | 6.84 | 3,379 | Radial Velocity2026 | View habitability →NASA Archive ↗ |
| LHS 1140 b LHS 1140 | 1.73 | 5.6 | 0.43 | -47 °C (226 K) | 24.74 | 0.095 | 14.99 | 3,096 | Transit2017 | View habitability →NASA Archive ↗ |
| TOI-6002 b TOI-6002 | 1.65 | Unknown | 1.68 | 48 °C (321 K) | 10.9 | 0.057 | 32.03 | 3,229 | Transit2024 | View habitability →NASA Archive ↗ |
| GJ 251 c GJ 251 | 1.8 | Unknown | 0.4 | -57 °C (216 K) | 53.65 | 0.196 | 5.58 | 3,342 | Radial Velocity2025 | View habitability →NASA Archive ↗ |
Click a planet’s name for its habitability assessment. Sorting by Earth similarity compares radius and starlight only; it is not a habitability ranking.
Search the full catalog, independently of the ranges. A star search finds its known planets. The starting screen is a size-and-starlight check, not a habitability rating.
Enter a planet or star name to begin.
Simulation of starlight received and planetary temperature
In this section, choose a hypothetical planet’s star type and orbital distance to explore the starlight it receives and its estimated temperature, accounting for reflectivity and atmospheric warming. Start with Earth-like settings and change one variable at a time. We use a simplified average-temperature estimation model.
Adjust your model
Sun-like. Earth receives about 1 S⊕ at 1 AU around this kind of star.
1 AU is Earth’s distance from the Sun; 1 S⊕ is Earth’s starlight.
Your test planet
Sun-like (G): 1 L☉, habitable zone from 0.77 to 1.69 AU.
Zone boundaries: 0.767–1.69 AU. Planet orbit: 1 AU. The distance scale adapts to keep the zone and planet visible.
Incoming energy relative to Earth = 1.
Energy balance without atmospheric warming.
Equilibrium temperature + your warming setting.
Habitable-zone boundary assumptions · 0.35–1.7 S⊕
Choose the minimum and maximum starlight for the green band. Each edge is placed at d = √(L / Sₑdge), using star luminosity L. These approximate classroom assumptions change the band and location badge, but not incoming starlight, temperature, or the physical orbit. A green-band position is a starlight check, not proof of liquid water or life.
Planet reflectivity · 0.3
Reflectivity (albedo) is the fraction of incoming light reflected away. A higher value reduces absorbed energy, lowering both temperature estimates; incoming starlight and orbital position stay the same. The calculation assumes evenly redistributed heat and idealized thermal radiation.
Greenhouse effect · +33 K
Adds the chosen warming in kelvin to equilibrium temperature. Only the estimated surface temperature changes; the orbit and zone boundaries stay the same. This adjustable offset is a teaching simplification, not a calculation from atmospheric composition. The model does not calculate weather, clouds, climate feedbacks, or atmospheric pressure. NASA: Earth’s energy budget ↗
How the simulator calculates these results
- Star brightness → incoming starlight. Each star preset has a radius R (in Sun radii) and temperature T. Its relative luminosity is L = R² × (T / 5,772 K)⁴. At orbital distance d (in AU), S = L / d². Moving twice as far away gives one-quarter as much starlight.
- Absorbed starlight → equilibrium temperature. The model balances absorbed energy against emitted heat, averaged across the whole planet. With reflectivity A, Tₑq = 255 K × [S × (1 − A) / 0.7]¼. The fourth root comes from heat radiation increasing with temperature to the fourth power. Earth’s reference reflectivity is 0.30, so 70% of incoming energy is absorbed.
- Add atmospheric warming. Estimated surface temperature = Tₑq + warming. The default adds 33 K: at Earth’s starlight and reflectivity, 255 K becomes 288 K (about 15 °C). Calculations use kelvin; displayed Celsius values subtract 273.15.