Skip to main content

New type of ocean-covered ‘Hycean’ exoplanet could support life

When it comes to looking for life elsewhere in the universe, we tend to be very Earth-centric: We look for planets that are similar to our own, assuming that life elsewhere will be similar to us and require similar conditions. However, a new type of exoplanet has been identified by astronomers at the University of Cambridge, and even though it is very different from Earth it could still support life.

The new class of planet is called a “Hycean” planet, meaning an ocean-covered world with abundant hydrogen in its atmosphere. The researchers believe that this type of planet could be common and as they are potentially habitable this significantly increases the possible locations to search for life outside our solar system.

 Artist's impression of a Hycean planet.
Artist’s impression of a Hycean planet. Amanda Smith

“Hycean planets open a whole new avenue in our search for life elsewhere,” said lead researcher Nikku Madhusudhan from the University of Cambridge’s Institute of Astronomy in a statement.

These planets are typically larger than Earth, at up to 2.6 times its size, and can be hotter as well, with atmospheric temperatures of up to 200 degrees Celsius. However, despite these high temperatures their oceans could still host microbial life, as suggested by another recent study into a large exoplanet with a hydrogen-rich atmosphere. This study found that there could be liquid water on the planet’s surface beneath its atmosphere. If this is true for Hycean planets as well, then the habitable zone — the area around a star where a planet must orbit for liquid water to be able to exist on its surface — could be larger for these planets than for other types of planets.

“Essentially, when we’ve been looking for these various molecular signatures, we have been focusing on planets similar to Earth, which is a reasonable place to start,” said Madhusudhan. “But we think Hycean planets offer a better chance of finding several trace biosignatures.”

Biosignatures are chemical indications of life and are one of the main ways that researchers look for life elsewhere in the universe.

“A biosignature detection would transform our understanding of life in the universe,” said Madhusudhan. “We need to be open about where we expect to find life and what form that life could take, as nature continues to surprise us in often unimaginable ways.”

The research is published in The Astrophysical Journal.

Editors' Recommendations

Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
Watch a video of an exoplanet orbiting its star — made from 17 years of observations
Artist’s impression of the planet Beta Pictoris b orbiting its star.

It's rare that we get to see exoplanets themselves. Most often, planets in other star systems are too small and too dim to be directly detected, so astronomers infer their presence based on their effects on their host stars. But occasionally, it is possible to image a star directly -- and recently, astronomers managed to create not only an image, but a video of an exoplanet orbiting its star.

17 years of real footage of an exoplanet (Beta Pic b)

Read more
Hubble watches an extreme exoplanet being stripped by its star
This artist's illustration shows a planet (dark silhouette) passing in front of the red dwarf star AU Microscopii.

Of the many strange exoplanets discovered to date, one of the most extreme has to be a world called AU Mic b. This Neptune-sized planet orbits close enough to its star that a year there lasts just over a week, and it is bombarded by dramatic flares from its host star which cook the planet with radiation.

Recently, Hubble observed this system to learn more about the relationship between the exoplanet and its star, technically called AU Microscopii.  The planet's hydrogen atmosphere is blown away by radiation from the star, but there were confusing findings that seemed to show that no atmosphere was being lost at some times, but significant amounts of atmosphere were lost at other times.

Read more
Here’s why scientists think life may have thrived on the ‘hell planet’ Venus
The planet Venus.

When you look at Venus today, it doesn’t seem like a very welcoming place. With surface temperatures hotter than an oven, atmospheric pressure equivalent to being 3,000 feet deep in the ocean, and no liquid water anywhere that we’ve seen, it seems like the opposite of a comfortable environment in which life could emerge.

But in the last decade, scientists have begun to wonder whether this “hell planet” could once have been habitable. Billions of years ago, Venus could have been a cooler, wetter place, with oceans not unlike our own here on Earth.

Read more