Hycean world Archives

March 14, 2024March 14, 2024 by Evan Gough

Another Hycean Planet Found? TOI-270 d

Artist's impression of the surface of a hycean world. Hycean worlds are still hypothetical, and have large oceans and thick hydrogen-rich atmospheres that trap heat. They could be habitable even if they're outside the traditional habitable zone. Credit: University of Cambridge

Hycean planets may be able to host life even though they’re outside what scientists consider the regular habitable zone. Their thick atmospheres can trap enough heat to keep the oceans warm even though they’re not close to their stars.

Astronomers have found another one of these potential hycean worlds named TOI-270 d.

February 22, 2024February 22, 2024 by Scott Alan Johnston

If Hycean Worlds Really Exist, What are Their Oceans Like?

Artist's impression of possible hycean world K2-18 b. Credit: NASA, ESA, CSA, Joseph Olmsted (STScI)

Astronomers have been on the hunt for a new kind of exoplanet in recent years – one especially suited for habitability. They’re called hycean worlds, and they’re characterized by vast liquid water oceans and thick hydrogen-rich atmospheres. The name was coined in 2021 by Cambridge astronomer Nikku Madhusudhan, whose team got a close-up look at one possible hycean world, K2-18b, using the James Webb Space Telescope in 2023. In a newly accepted paper this January, Madhusudhan and coauthor Frances Rigby examined what the internal structure of hycean planets might look like, and what that means for the possibility of finding life within.

January 29, 2024January 29, 2024 by Evan Gough

Another Explanation for K2-18b? A Gas-Rich Mini-Neptune with No Habitable Surface

Artist depiction of the mini-Neptune K2-18 b. Credit: NASA, CSA, ESA, J. Olmstead (STScI), N. Madhusudhan (Cambridge University)

Exoplanet K2-18b is garnering a lot of attention. James Webb Space Telescope spectroscopy shows it has carbon and methane in its atmosphere. Those results, along with other observations, suggest the planet could be a long-hypothesized ‘Hycean World.’ But new research counters that.

Instead, the planet could be a gaseous mini-Neptune.

January 16, 2024January 16, 2024 by Evan Gough

Is K2-18b Covered in Oceans of Water or Oceans of Lava?

This illustration shows what exoplanet K2-18 b could look like based on science data. NASA’s James Webb Space Telescope examined the exoplanet and revealed the presence of carbon-bearing molecules. The abundance of methane and carbon dioxide, and shortage of ammonia, support the hypothesis that there may be a water ocean underneath a hydrogen-rich atmosphere in K2-18 b. But more extensive observations with the JWST are needed to understand its atmosphere with greater confidence. Image Credit: By Illustration: NASA, ESA, CSA, Joseph Olmsted (STScI)Science: Nikku Madhusudhan (IoA)

In the search for potentially life-supporting exoplanets, liquid water is the key indicator. Life on Earth requires liquid water, and scientists strongly believe the same is true elsewhere. But from a great distance, it’s difficult to tell what worlds have oceans of water. Some of them can have lava oceans instead, and getting the two confused is a barrier to understanding exoplanets, water, and habitability more clearly.

January 4, 2024January 4, 2024 by Brian Koberlein

Want to Find Life? See What's Missing in an Atmosphere

Illustration potentially habitable worlds. Credit: Christine Daniloff, MIT; iStock

The world runs on carbon. Not just fossil-fuel-driven human society, but all life on Earth. Carbon-based organic molecules are a part of every living thing on Earth. Along with oxygen, nitrogen, and water, carbon is a necessary ingredient for life as we know it. So one way to look for life on other worlds could be to look for carbon in its atmosphere. But a new study shows that it’s actually a lack of carbon that could be the best clue to life on another world.

September 11, 2023September 11, 2023 by Brian Koberlein

JWST Might Have Imaged a Hycean World for the First Time, With a Hydrogen-Rich Atmosphere and a Deep Planet-Wide Water Ocean

Despite its great oceans, Earth is not really an ocean world. It has less water than icy moons such as Europa and Enceladus, a relatively thin nitrogen-rich atmosphere, and vast continents that rise above sea level. A true ocean world would have no continents, a warm sea hundreds of kilometers deep, and a thick hydrogen and water-rich atmosphere. They are known as hydrogen-ocean planets or hycean worlds. While we’ve long thought they exist, the James Webb Space Telescope may now have found one.

September 4, 2021September 4, 2021 by Matt Williams

Ocean Worlds With Hydrogen-Rich Atmospheres Could be the Perfect Spots for Life

The search for planets beyond our Solar System (extrasolar planets) has grown by leaps and bounds in the past decade. A total of 4,514 exoplanets have been confirmed in 3,346 planetary systems, with another 7,721 candidates awaiting confirmation. At present, astrobiologists are largely focused on the “low hanging fruit” approach of looking for exoplanets that are similar in size, mass, and atmospheric composition to Earth (aka. “Earth-like.”)

However, astrobiologists are also interested in finding examples of “exotic life,” the kind that emerged under conditions that are not “Earth-like.” For example, a team of astronomers from the University of Cambridge recently conducted a study that showed how life could emerge on ocean-covered planets with hydrogen-rich atmospheres (aka. “Hycean” planets). These findings could have significant implications for exoplanet studies and the field of astrobiology.