Earth Similarity Index

ESI (Earth similarity index) is a scale for a planet if it is similar to Earth, it ranges from 0 to 1. 1.00 is earth and 0.00 is a planet that is the opposite of earth. Having a high ESI means it is probably habitable, but sometimes a planet is even better for life than Earth so it isn't similar to Earth, so this is not accurate to measure how habitable the planet is. For example, mars has 0.7 ESI.