1. What is Planetary Equilibrium Temperature?

The planetary equilibrium temperature is the theoretical temperature of a planet assuming it is a black body being heated only by its parent star. This calculation provides an estimate of a planet's surface temperature based on stellar properties and orbital characteristics.

2. How Does the Calculator Work?

The calculator uses the planetary equilibrium temperature equation:

Where:

• \( T_{star} \) — Stellar temperature (K)
• \( R_{star} \) — Stellar radius (m)
• \( a \) — Semi-major axis (orbital distance in meters)
• \( A \) — Planetary albedo (0-1)

Explanation: The equation calculates the temperature a planet would reach when the energy received from its star is balanced by the energy radiated back into space.

3. Importance of Equilibrium Temperature Calculation

Details: Calculating planetary equilibrium temperature is crucial for exoplanet studies, habitability assessments, and understanding planetary climate systems. It provides a baseline for comparing actual observed temperatures and assessing atmospheric effects.

4. Using the Calculator

Tips: Enter stellar temperature in Kelvin, stellar radius in meters, semi-major axis in meters, and albedo as a value between 0 and 1. All values must be positive, with albedo between 0 and 1 inclusive.

5. Frequently Asked Questions (FAQ)

Q1: Why is this considered an "equilibrium" temperature?
A: It represents the temperature at which the energy received from the star equals the energy radiated back into space, creating a thermal equilibrium.

Q2: How does albedo affect the equilibrium temperature?
A: Higher albedo (more reflective surface) results in lower equilibrium temperature as more stellar radiation is reflected rather than absorbed.

Q3: What are typical equilibrium temperature ranges?
A: Temperatures range from near absolute zero for distant planets to thousands of Kelvin for close-orbiting planets around hot stars.

Q4: What are the limitations of this calculation?
A: This is a simplified model that doesn't account for atmospheric greenhouse effects, internal heat sources, or tidal heating, which can significantly alter actual surface temperatures.

Q5: How does this relate to habitable zone calculations?
A: Equilibrium temperature is a key factor in determining the habitable zone around a star, where liquid water could potentially exist on a planet's surface.