‘Water world with boiling ocean’ discovered in deep space

Astronomers have discovered a “water world with a boiling ocean” in deep space. A major discovery made by the James Webb Telescope is raising controversy about conditions on the surface of a distant planet.

Scientists have observed a distant planet that may have been entirely covered by a deep ocean, with findings that advance the search for habitable conditions beyond Earth, The Guardian writes.

Observations by NASA’s James Webb Space Telescope (JWST) revealed water vapor and the chemical signatures of methane and carbon dioxide in the exoplanet’s atmosphere, which is twice the radius of Earth and about 70 light-years away. According to researchers at the University of Cambridge, this chemical mixture is consistent with a watery world, where the ocean would cover the entire surface, and a hydrogen-rich atmosphere, although they do not suggest a pleasant, inviting seascape.

“Ocean temperatures can reach 100 degrees [по Цельсию] or more,” said Professor Nikku Madhusudhan, who led the analysis. At high atmospheric pressure, such a hot ocean could still be liquid, “but it is unclear whether it would be habitable,” he added.

This interpretation is supported by a paper published in the journal Astronomy and Astrophysics Letters, but is disputed by a Canadian team that made additional observations of the same exoplanet, known as TOI-270 d. They found the same chemicals in the atmosphere, but argue that the planet would be too hot for liquid water—perhaps 4,000 degrees Celsius—and would instead have a rocky surface covered with an incredibly dense atmosphere of hydrogen and water vapor.

Whichever view prevails, these latest observations demonstrate the James Webb Telescope’s stunning discoveries about the nature of planets beyond our solar system. The telescope captures starlight that has been filtered through the atmospheres of orbiting planets to provide detailed information about the chemical elements present. From this, astronomers can build a picture of conditions on the planet’s surface—and the likelihood that life could survive there.

Evidence for the existence of the TOI-270 d ocean is based on the absence of ammonia, which fundamental chemistry predicts would be present naturally in a hydrogen-rich atmosphere. But ammonia is highly soluble in water, and so would be depleted in the atmosphere if there were an ocean below. “One interpretation is that it is a so-called ‘Githian’ world – with a water ocean under a hydrogen-rich atmosphere,” says Professor Madhusudhan.

Conditions on a distant planet are very different from those on Earth. TOI-270 d is locked into a tidal cycle, meaning one side is constantly facing its star while the other is in perpetual darkness, creating an extreme temperature contrast.

“The ocean would be extremely hot on the day side. The night side could potentially have habitable conditions,” says Madhusudhan. But there would be a pressing atmosphere with pressure tens or hundreds of times greater than the pressure on the Earth’s surface, and steam rising above the ocean. The waters likely reach depths of tens to hundreds of kilometers, with a seafloor covered in high-pressure ice and a rocky core underneath.

Professor Björn Bennecke from the University of Montreal has conducted additional observations of the planet and questions the “Gytsian world” hypothesis. “The temperature, in our opinion, is too high for water to be liquid,” he said, adding that the atmosphere appears to contain significant amounts of water vapor – too much for the existence of an ocean to be plausible. Benneke estimates that surface temperatures can reach 4,000°C, with water in a supercritical state where the distinction between liquid and gas becomes blurred. “It’s almost like a thick, hot liquid,” he said.

Both teams discovered carbon disulfide, which is associated with biological processes on Earth but can also come from other sources. However, there was no evidence of another biosignal molecule, dimethyl sulfide (DMS).

“We can’t link carbon disulfide to biological activity,” says Madhusudhan. – In an atmosphere rich in hydrogen, it is relatively easy to obtain. But if we can measure this unique molecule, it is promising that we will be able to measure habitable planets in the future.”

“We need to be extremely careful in how we report findings at these types of sites,” he added. “It’s easy for the public to latch on to the idea that we’re already discovering life.”

Astronomer Dr Joe Barstow comments: “The JWST spectra of these minor planets are really exciting because these are completely new conditions for which we have no equivalent in the solar system.”

Barstow notes that further observations aimed at determining the amount of water vapor in the atmosphere will help clarify the likelihood of the existence of an ocean. “It’s really exciting and really nice that two teams looked at the same data set and came up with the same chemical composition,” she added.