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Planetary Equilibrium Temperature Equation:
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The planetary equilibrium temperature is the theoretical temperature of a planet's surface if it were a black body being heated only by its parent star. This calculation assumes the planet has no atmosphere and no internal heat source.
The calculator uses the equilibrium temperature equation:
Where:
Explanation: The equation balances the incoming stellar radiation (adjusted for albedo) with the outgoing thermal radiation from the planet.
Details: This calculation provides a baseline for understanding a planet's thermal environment and is fundamental in planetary science and astrobiology. It helps estimate surface temperatures and potential habitability.
Tips: Enter incident flux in W/m², albedo as a decimal between 0 and 1, and the Stefan-Boltzmann constant (default value provided). All values must be valid (flux > 0, 0 ≤ albedo ≤ 1, σ > 0).
Q1: How does this differ from actual planetary temperatures?
A: Real planets often have different surface temperatures due to atmospheric effects, internal heating, and other factors. This is a simplified model.
Q2: What is typical incident flux for planets?
A: Earth receives about 1361 W/m² (solar constant). Flux decreases with distance from star (inverse square law).
Q3: What are typical albedo values?
A: Earth ~0.3, Venus ~0.76, Moon ~0.12. Ice and clouds increase albedo; dark surfaces decrease it.
Q4: Why use the 1/4 power in the equation?
A: This comes from the Stefan-Boltzmann law where radiant energy is proportional to T⁴, so we take the fourth root to solve for T.
Q5: Can this be used for exoplanets?
A: Yes, this is commonly used to estimate temperatures of exoplanets when their stellar flux and albedo are known or estimated.