The search for life beyond our planet continues, and one of the most underappreciated tools in an astrobiologists' toolkit is statistics. While it might not be as glamorous as directly imaging a planet’s atmosphere or finding a system with seven planets in it, statistics is absolutely critical if we want to be sure that what we’re seeing is real and not just an artifact of the data, or of our observational techniques themselves. A new paper by Caleb Traxler and their co-authors at the Department of Information and Computer Science at UC Irvine takes on that challenge head-on by statistically analyzing a set of about 10% of the total number of exoplanets found and judging their habitability.

Kepler 538-b is larger than Earth, and has a much higher temperature, but it still falls within the realm of potentially habitable. But that rarity points to another important finding from the paper - Earth is a statistical rarity in terms of planets, but not one that requires some miraculous confluence of planetary and stellar characteristics. Using a statistical technique called the Mahalanobis distance analysis, the authors found that Earth is around 69.4% different in terms of “statistical unusualness”, making it rare, but not too rare.

As the science of astrobiology and exoplanets moves forward, continuing this type of statistical analysis will provide valuable context that could otherwise mislead or obfuscate the areas that have the most potential to answer one of the most important questions to humanity - are we alone? With increasingly powerful observational equipment pointed in the right direction, we might soon have a definitive answer to that question.