The World World Theory
According to scientists, some exoplanets might be nothing but water worlds, i.e., rocky planets with global oceans covering their entirety. A recent Harvard University research suggests that the planet Earth was previously a water world. It had a small portion of land, and the rest of it was a global ocean.
Experts rely on the amount of water that is available in the planet’s mantle. If we can recall the lessons from school on the water cycle on Earth, we would remember the constant movement of water. It starts with the evaporation from a water body to condensation and thus resulting in the rain that fills up lakes and rivers. This completes the water cycle.
Water Under the Earth’s Surface
However, water also plays a major role in processes beneath the surface. The explosiveness of a volcano depends on the percentage of water present in magma. Also, the formation and the migration of crude oil and petroleum are impossible without the presence of water below the ground. Seawater also passes through the surface into the oceanic crust.
By hydrating the igneous rocks, it turns them into hydrous minerals. In this very form, water percolates down and reaches the mantle. While discussing the evidence which proves that Earth was once a water world, you have to go deeper.
At the surface of the planet, maximum water is in the form of oceans. Underneath the surface, minerals can include a good deal of water while forming rocks. The water storage capacity is the percentage of water that dissolves in the minerals present in the Earth’s mantle. And this capacity tends to decrease as the temperatures rise.
The Water Exchange
Over some billion years, the water exchange between the planet’s surface and interior might have a huge impact on the volume of the surface oceans. The results derived from various studies indicate that reassessing is necessary for the volume of the surface oceans that has stayed constant over the years.
Deep down below the earth’s surface, water storage happens in two high-pressure forms of olivine. Whatever has been inferred regarding the minerals’ water storage capacities has been heavily dependent on the mantle’s high temperatures and pressures. But, experts wanted to do more thorough research on the storage capacity in terms of different temperatures.
What can be the reason? When the planet was younger, the matter was way hotter than what it is today. This implies that the mantle didn’t have a large water storage capacity in comparison to recent times. If the mantle was unable to store that much water, then what happened to the water? Did the surface act as the reservoir?
The mantle’s water storage capacity was greatly affected as the mineral’s storage capacity was highly dependent on temperature. The ratio of the mantle’s water storage capacity to the mass of the surface ocean in today’s times is 1.86:4.41. So, what is the inference from this? A bulk of the planet’s water was present on the surface 2.5 to 4 billion years ago. The mantle was way hotter than it’s today and couldn’t store that much water. It won’t be wrong to state that Earth’s surface was entirely covered by water with hardly any landmass.
The Unanswered Question
The question that remains without a concrete answer is, what happened to so much water?. Much of that water must have absorbed in the mantle. With a decrease in the mantle’s temperature, the storage capacity automatically increased. This process went on until the water you see in the lakes, rivers, and oceans today remained. As per the new findings, water covered almost 100% of the surface of the planet. It takes up 71% of the surface now. Another study revealed that around 3.2 million years ago, there was not such a big landmass that you see now.
The Milky Way galaxy can have millions of ocean worlds, and this can be a fascinating study. Planets, as well as moons, can be a water world. The very thought of this is exciting to the researchers, and they are going deeper in their research. There can be some more exciting discoveries soon. And it is impossible to rule out the possibilities of alien life on a far-off planet. However, we cannot jump to conclusions until we have ample evidence.