Secrets Of The Ocean Worlds

If physics and chemistry are the same throughout the universe, is biology too?

- Lee Cavendish

Earth isn’t the only world which accommodates water. There are moons in the Solar System half the size of Earth that hold much more. These are known as ocean worlds. Astronomers continue to scrutinise these in great detail, as they have the potential to change how biology is viewed throughout the universe. “An ocean world is any planet, or sometimes moon, that has at least ten times the amount of water that Earth does. For reference, Earth is about 0.1 per cent water, so an ocean world has a water content of one per cent or greater,” explains Dr Lynnae Quick, an ocean worlds planetary scientist at NASA’s Goddard Space Flight Center in Maryland, to All About Space.

Water is a necessity for life as we know it. Every living thing on Earth consumes water to stay hydrated and survive. Water also provides opportunities for exploration, whether it is taking to the oceans to discover a new bit of land or diving into the depths below, where many mysteries remain unanswered. Astrobiologists now want to up the ante and explore the oceans of other worlds millions of miles – or possibly even light-years – away in order to find signs of alien life.

How worlds end up having global oceans, either visible on the surface or buried underneath an icy exterior, is a story in itself. Water does not float through space as liquid droplets waiting to splash down on a surface. As space is so cold, water travels through space as grains of ice. As new planetary systems begin to form around a young star, water can stay as these icy grains beyond a certain radius, known as the ‘ice line’.