May 22, 2017 0516 GMT
Fergus Simpson, a researcher at the University of Barcelona's Institute of Cosmos Sciences, used Bayesian probability to build a statistical model to predict the most likely composition of a habitable exoplanet, according to UPI.
The model suggested Earth's unique balance of land and water is especially unique. Scientists still aren't sure why or how planet Earth managed to strike such a perfect balance.
According to the model, such balance is unlikely to be found elsewhere. Instead, habitable worlds are most likely to feature mostly oceans.
Simpson's model considers the role of the deep water cycle, as well as erosion and deposition systems, in creating the unique land-water balance found on Earth.
His research suggested planets with smaller oceans are at risk of becoming dominated by deserts.
Simpson believes scientists' understanding of habitable world is skewed by what's called the ‘anthropic principle’, which is the idea that the very existence of sentient life biases human understanding of the Universe.
Our very existence, in other words, seems inevitable, even if statistics suggested otherwise.
Put another way: Human observations of the Universe can only manifest on planets where humans can live.
Simpson said, "Our understanding of the development of life may be far from complete, but it is not so dire that we must adhere to the conventional approximation that all habitable planets have an equal chance of hosting intelligent life.”
Simpson detailed his model and its implications in the latest issue of the Monthly Notices of the Royal Astronomical Society.
In previous work, Simpson has suggested most habitable worlds are smaller than Earth and that sentient aliens are likely to be significantly larger than humans.