A recently discovered class of exoplanets, known as Hycean worlds, is offering astronomers more avenues for exploration, as well as more possibilities for life beyond Earth. The term ‘Hycean’ is derived from hydrogen and ocean. This implies that these planets potentially boast vast planet-wide oceans and are surrounded by hydrogen-rich atmospheres.
These uniquely alien worlds are significantly larger than Earth, stretching up to 2.6 times the diameter of our home planet. They also feature astonishingly high temperatures reaching up to 200 degrees Celsius, alongside their dense hydrogen atmospheres. This makes them an intriguing middle ground between Earth and giant planets like Neptune or Uranus.
No Analogues in Our Solar System
The Hycean worlds do not have any direct analogs in our own Solar System. They are often referred to as super-Earths or mini-Neptunes based on educated assumptions about their bulk compositions, which are derived from their densities. Unlike most mini-Neptunes, these planets could possibly possess solid surfaces akin to Earth’s.
Despite being larger and hotter than Earth, many of the currently identified Hycean candidates have the potential to host large oceans. A considerable number of them orbit incredibly close to their stars, a situation that results in tidal locking. This means that they have one perpetually heated dayside and an eternally dark nightside. On the other hand, some Hyceans orbit their stars from great distances, thus receiving very little stellar radiation. However, notwithstanding such extreme conditions, the possibility of life is not ruled out.
Tidal Locking and its Implication
Tidal locking is a phenomenon where an object’s orbital period matches its rotational period. This unique characteristic of several Hycean worlds might make them more conducive to supporting life, at least in theory.
The Significance of Hycean Worlds
The conditions on these planets could be somewhat comparable to the more extreme aquatic environments on Earth, increasing the chance of supporting microbial life. The discovery of Hycean worlds significantly accelerates the search for extraterrestrial life.
Hycean worlds are not merely reminiscent of Earth due to their large or even complete ocean coverage, but could also potentially host forms of life that differ from what we know on Earth.
Exoplanets: Planets Outside the Solar System
An exoplanet, also known as an extrasolar planet, is a planet outside our Solar System. The first confirmed detection of such a planet was made in 1992, and since then, over 4,400 exoplanets have been discovered.
Exoplanets are notoriously hard to spot directly with telescopes due to their stars’ overpowering glare. For this reason, astronomers rely on other methods to detect and study exoplanets, such as observing the effects these planets have on the stars they orbit.
