How many planets exist that have water? According to the conclusions of a new investigation, many more than we all thought.
Water is the most valuable element for supporting life on Earth, and the water cycle is what makes our planet’s climate stable and hospitable. When scientists search for possible signs of life on other planets, water is an indisputable part of this search. Although other life forms could exist without this requirement, we looked at what we know and planets with water are at the top of this list.
We can find water on moons as well, with several moons in the solar system, such as Jupiter’s moons of Ganymede and Europa , suspected of containing large amounts of water.
More common than imagined
Now, a new study suggests that the number of aquatic planets that may be in the galaxy would be much higher than expected and could even have water and rock in equal parts. The water would likely be embedded in the rock, rather than flowing like oceans or rivers on the surface, as it does here on our planet.
“It was a surprise to see evidence of so many aquatic worlds orbiting the most common type of star in the galaxy,” says Rafael Luque, a postdoctoral researcher at the University of Chicago and co-author of the paper published in the journal Science. “It has huge consequences for the search for habitable planets.”
The researchers used the Transiting Exoplanet Survey Satellite (TESS) to study the radius and mass of 34 newly detected planets around an M dwarf, the most common star shape we see around us in the galaxy. The densities of a large percentage of the planets suggested that they were too light for their size to be made of pure rock. While a vision of a world completely covered in water may come to mind, their analysis revealed that many more planets than expected were half water and half rock. The researchers suggest that the water could exist mixed with the rock or in pockets below the surface.
Those conditions would be similar to Europa, Jupiter’s fourth largest moon, which is thought to have liquid water underground. “I was surprised when I saw this analysis : Many people in the field, myself included, assumed these were all dry, rocky planets,” said University of Chicago exoplanet scientist Jacob Bean.
Although the evidence is compelling, Bean said he and other scientists would like to see “irrefutable proof” that one of these planets is a water world. That’s something scientists hope to do with JWST, NASA’s recently launched space telescope that never stops giving us joy by showing us never-before-seen intricate details of the cosmos.
Referencia: Rafael Luque and Enric Pall�. Density, not radius, separates rocky and water-rich small planets orbiting M dwarf stars. Science, 2022 DOI: DOI: 10.1126/science.abl7164