Most Habitable Planets May Be Water Worlds

A majority of habitable planets may be water worlds that lack dry land and are dominated by oceans that cover 90 percent of their surface area, a new study has suggested. A team of researchers from the University of Barcelona, Spain, has created a statistical model based on Bayesian probability to predict the ratio of land and water on exoplanets that can support life.

A closer look at Earth also shows that it is not too far removed from being completely drenched in water, with 71 percent of the area covered with it. The scientists believe that a key factor behind the appearance of advanced life is the fine balance between land and sea found on Earth. For a planetary surface to support large areas of both land and ocean, the right ratio has to be struck between the water volume it retains over time and the amount of storage space that exists in oceanic basins.

"A scenario in which the Earth holds less water than most other habitable planets would be consistent with results from simulations,” lead researcher Dr. Fergus Simpson said, according to The Economic Times. “It could help explain why some planets have been found to be a bit less dense than we expected."

But the good balance on Earth from evolution of life’s viewpoint has been a long-standing mystery. Dr. Simpson suggests that anthropic principle could be one explanation. According to this principle, if the universe had not evolved the way it has, people would not have been present to observe it.

The researchers also suggested that the unusual ratio of land and water on Earth could be another example of the fine tuning required for intelligent life to exist. The study can be seen in the Monthly Notices of the Royal Astronomical Society.