The search for alien life has always been based on looking for planets that can harbor life; at least, life as we understand it. And life, as we understand it, is based on the presence of water. Thus, all searching for extra-terrestrial life has been based on identifying planets outside our solar system that have water.
Well, a new study states that at least thirty percent—roughly one-in-three—of all exoplanets (planets outside our solar system) that are bigger than Earth are also home to ecosystems that contain water. In fact, scientists show that water is actually a big part of the composition of these planets, all of which are between two and four times the size of our home planet.
Exoplanets orbiting other stars were first discovered in 1992 and since then scientific interest in these planets has been very high. Of course, a major part of the investigation and analysis of these planets has been over their composition, mostly to determine whether they could be suitable for the development of life.
New evaluations of these planets—with information from the Kepler Space Telescope and the Gaia mission—suggest that many of these known planets could actually contain as much as 50 percent water. This is significantly more than Earth’s 0.02 percent water content (by weight).
Harvard University’s Dr. Li Zeng commented, “It was a huge surprise to realize that there must be so many water-worlds.”
Since we started hunting for exoplanets, scientists have managed to confirm around 4000 of them. And most of these exoplanets fall into one of two categories: those averaging about 2.5 times the radial size of Earth and those averaging around 1.5 times the radial size of Earth.
With this all in mind, then, a group of international scientists has developed a new model to estimate these planet’s internal structures.
Zeng goes on to say, “We have looked at how mass relates to radius and developed a model which might explain the relationship.” The model also explains that exoplanets that are 1.5 times the size of Earth (radius) tend to not only be rocky planets, but also 5 times the mass of Earth; and planets at 2.5 times the radius of Earth tend to be watery worlds (and have a mass at 10 times that of Earth).