Satellites (pixabay photo)
NASA reports two distant planets likely made of water, according to research conducted using NASA’s Hubble and Spitzer telescopes.
The stars, called “water worlds,” orbit a red dwarf star, the smallest and most interesting type of star, according to a press release from NASA’s Jet Propulsion Laboratory.
The watery planets are 218 light-years away in the constellation Lyra, NASA says. They are “unlike planets found in our solar system,” the agency said.
The finding that the planets are likely composed mostly of water comes from a study published in the journal Nature Astronomy on Thursday. A research team led by Caroline Piole, a PhD student at the University of Montreal’s Institute for Planetary Studies, used NASA’s Hubble and Spitzer Space Telescopes to observe the distant planetary system.
The planetary system they studied is called Kepler-138 because it is located in the field of view of NASA’s Kepler spacecraft. Researchers knew of the existence of three exoplanets – the term for planets outside our solar system – within the Kepler-138 system, but only now discovered two which are probably made of water.They also discovered evidence of a previously undescribed fourth planet.
But the finding is not as simple as it may seem. The scientists did not detect water directly in the planets Kepler-138c and Kepler-138d. Instead, they compared the sizes and masses of the planets to models for comparison.
Comparing the planets to the models, they found “that a significant fraction of their volume—up to half of it—should be made of materials lighter than rock but heavier than hydrogen or helium.”
More in-
Water is the most likely candidate for a material lighter than rock but heavier than hydrogen or helium, NASA says.
“In the past, we thought that planets that were slightly larger than Earth were big balls of metal and rock, like enlarged versions of Earth, and that’s why we called them super-Earths,” said Björn Benneke, author of the study. Professor of Astrophysics at the University of Montreal, Ed. “However, we have now shown that these two planets, Kepler-138c and d, are completely different in nature and that a large fraction of their entire volume is likely composed of water.”
“This is the best evidence yet for water worlds, a type of planet that astronomers have determined has existed for a long time,” Banke continued.
The high temperatures on these planets mean they may be enveloped in steam atmospheres, according to NASA.
“The temperature in Kepler-138d’s atmosphere is likely above the boiling point of water, and we expect a thick, dense atmosphere made of steam on this planet,” Piol said in a statement. “Only below the steam atmosphere can there be liquid water at high pressure, or even water in another phase that occurs at high pressures, called supercritical fluid.”
The “water worlds” are outside their star’s habitable zone—the region where temperatures allow liquid water on a rocky planet’s surface, which could support life. But the new planet described by the researchers, Kepler 138-e, does fall into just the right region, according to the publication.
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