Free Planet Equilibrium Temperature Calculator

Compute the radiative equilibrium temperature of a planet from stellar properties and albedo: T_eq = T_star * sqrt(R_star / (2 * d)) * pow(1 - A, 0.25).

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Equilibrium Temperature

254.85 K

Equilibrium Temperature (C)-18.30 C

Equilibrium Temperature vs Star Temperature

View formula & how it works →

Planet Equilibrium Temperature

This is the temperature at which a planet radiates as much energy as it absorbs from its star.

Formula

T_eq = T_star * sqrt(R_star / 2d) * (1 - A)^(1/4)

  • *T_star* = stellar effective temperature
  • *R_star* = stellar radius
  • *d* = orbital distance
  • *A* = bond albedo

    • The factor of 2 (not 4) appears for a rapidly rotating planet that averages flux over the whole surface.

    Example Calculation

    Earth: T_star = 5778 K, R_star = 6.957e8 m, d = 1.496e11 m, A = 0.30.

    1. 01T_eq = 5778 * sqrt(6.957e8 / (2 * 1.496e11)) * (0.7)^0.25
    2. 02R / 2d = 6.957e8 / 2.992e11 = 2.325e-3
    3. 03sqrt(2.325e-3) = 0.04822
    4. 04(0.7)^0.25 = 0.9147
    5. 05T_eq = 5778 * 0.04822 * 0.9147 = 254.8 K

    Frequently Asked Questions

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