Vast and wild, the oceans of Earth are a sight to behold. They cover over two-thirds of our planet, and stretch down up to 10 kilometres. But out in space, a new type of alien planet puts our oceans to shame.

Meet the Hycean planets. These enormous water worlds can range up to 10x the mass of Earth. Some could be up to 90% water by mass, containing mega oceans that stretch hundreds or thousands of kilometres deep.

They carry ultra-thick hydrogen atmospheres, which trap heat and create enormous pressures, helping sustain liquid water across a wide range of temperatures. Reaching as high as 200 degrees Celsius, twice the boiling point of water. Their oceans are kept from boiling away by the extreme atmospheric pressures.

On the surface, these conditions would cook and crush a human being instantly. But down below, the waters would cool into a state that life on Earth might find familiar. And in the lowest depths, the ultra-thick oceans could condense into a mantle of exotic ice, known as ICE V.

Some may get tidally locked to their star. Dark hycean planets, where only the night side is cool enough for life. And there may also be cold hycean planets, where little sunlight falls.

But internal heat and a dense atmosphere, provide just enough warmth and pressure for liquid water. Compared to terrestrial planets like Earth, this dynamic range gives hycean planets a much wider habitable zone. Making them prime candidates for hosting alien life.

And researchers now believe that these worlds are extremely common in the universe, possibly outnumbering gas giants and terrestrial planets. Thanks to their large size and thick atmospheres, they will make for easier targets in the search for alien biosignatures. Recently, water vapour was discovered on K2-18B: A world with a mass and orbit that make it a strong contender for a hycean planet.

This world will soon be a target of study for the James Webb Space Telescope. Giving us our first glimpse, into a possibly hycean atmosphere. If there is life on Hycean world's, it could look very different than Earth's.

Evolving in hot, high-pressure conditions with exotic chemical soups. Without abundant oxygen for complex body plans, life forms here would probably remain microbial. But given the vast numbers and diversity of hycean planets, it's possible that somewhere huge lumbering lifeforms are roaming in oceans more vast than we can imagine.

Beings that will never know the taste of air or the sight of the stars. If most life in the universe is like this, we should feel grateful for our place. Free to plumb the depths of the oceans, and the reaches of the universe.

Subtitles Subtitles by Subtitles by Oliver W.

WATER WORLDS: Hideouts for Alien Life?