Earth Similarity Index Calculator

Earth Similarity Index Formula:

\[ ESI = \prod \left(1 - \frac{|x_i - x_{0_i}|}{x_i + x_{0_i}}\right)^{\frac{w_i}{\sum w}} \]

Planet Radius:

Earth radii

Density:

g/cm³

Escape Velocity:

km/s

Surface Temperature:

Earth Similarity Index (ESI):

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1. What is the Earth Similarity Index?

The Earth Similarity Index (ESI) is a measure of how similar a planet or moon is to Earth. It ranges from 0 (completely dissimilar) to 1 (identical to Earth). The index considers physical and chemical properties that are important for habitability.

2. How Does the Calculator Work?

The calculator uses the ESI formula:

\[ ESI = \prod \left(1 - \frac{|x_i - x_{0_i}|}{x_i + x_{0_i}}\right)^{\frac{w_i}{\sum w}} \]

Where:

\( x_i \) — Planet parameter value
\( x_{0_i} \) — Earth reference value
\( w_i \) — Weight for each parameter
\( \sum w \) — Sum of all weights

Explanation: The formula calculates geometric mean of similarity values for each parameter, weighted by their relative importance for Earth-like conditions.

3. Importance of ESI Calculation

Details: ESI helps astronomers and planetary scientists identify potentially habitable exoplanets and prioritize targets for further study in the search for extraterrestrial life.

4. Using the Calculator

Tips: Enter planetary parameters compared to Earth values. Radius in Earth radii, density in g/cm³, escape velocity in km/s, and surface temperature in Kelvin. All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What does ESI = 1 mean?
A: ESI = 1 indicates a planet identical to Earth in all measured parameters. No known exoplanet has ESI = 1.

Q2: What is considered a "Earth-like" ESI value?
A: Generally, ESI > 0.8 is considered Earth-like, while ESI > 0.6 indicates potential habitability.

Q3: Which parameters are most important for ESI?
A: Surface temperature typically has the highest weight, followed by density, escape velocity, and radius.

Q4: Can ESI predict actual habitability?
A: ESI indicates physical similarity to Earth but doesn't guarantee habitability. Other factors like atmosphere composition and magnetic fields are also crucial.

Q5: What are some known exoplanets with high ESI?
A: Kepler-438b (ESI=0.88), TRAPPIST-1e (ESI=0.85), and Proxima Centauri b (ESI=0.87) are among the highest ESI exoplanets discovered.