Discovering life on other planets is right now the main objective of scientists. But for there to be life, a series of conditions must be met, including the presence of water. However, how the liquid element appeared on our planet is still debated: did it appear during its formation or did it arrive almost by chance when an ice asteroid collided in our domain? Now researchers from the GLOBE Institute at the University of Copenhagen have published a study bidding for the first option. And, according to their calculations, this also happened on Venus and Mars, so they deduce that the Milky Way may be full of aquatic plants. The results have just been published in the journal ‘Science Advances’.

All our data suggest that water was part of the building blocks of the Earth from the beginning. And because the water molecule arises frequently, there is a reasonable probability that it applies to all the planets in the Milky Way. The decisive point for knowing if there is liquid water is the distance from the planet to its star, “explains Anders Johansen, from the Center for Star and Planet Formation and lead author of the study.

Are all planets made of ice?

Using a computer model, Johansen and his team calculated how quickly planets form and from which specific building blocks. So they observed that these worlds started from millimeter-sized dust particles of ice and carbon, which are known to orbit all young stars in the Milky Way. The same that 4.5 billion years ago accumulated in the formation of what would later become Earth. At the point where the Earth had grown by 1% of its current mass, our planet was formed by capturing masses of pebbles filled with ice and carbon. Then it grew faster and faster until, after 5 million years, it became as big as the planet we know today, ”says Johansen. Over time, the temperature on the surface increased sharply, causing the ice from the pebbles to evaporate towards the surface, so that today only 0.1% of the planet is made up of water, although 70% of the terrestrial surface is water ». The theory, which Johansen’s team has been working on for a decade, is known as “pebble accumulation”, planets are made up of small rocks that clump together, faster and faster to form.

The author explains that the H2O molecule is found everywhere in our galaxy and that therefore the theory opens the possibility that other planets have formed in the same way as Earth, Mars, and Venus. ‘All the planets in the Milky Way can be made up of the same building blocks, which means that planets with the same amount of water and carbon as Earth, and therefore potential places where there may (or could) be life, occur frequently around other stars in our galaxy, as long as the temperature is right, “he says.

Important opportunities for life

Therefore, it is logical to think that if some planets in our galaxy had the same basic components and the same temperature conditions as Earth, there will also be wide possibilities that they have approximately the same amount of water and continents as our planet. In this regard, Martin Bizzarro, co-author of the study, comments, With our model, all planets obtain the same amount of water, and this suggests that other planets may have not only the same amount of water and oceans but also the same amount of continents than here on Earth. It offers good opportunities for the emergence of life.
But there is also another possibility, if the amount of water present on the planets were random, they could be very different from each other. Some planets would be too dry to develop life, while others would be completely covered by water.

A planet covered by water, of course, would be good for maritime beings, but it would offer less than ideal conditions for the formation of civilizations that can observe the universe,” says Johansen, referring to the possibilities of finding intelligent life on other worlds.
Johansen and his research team look forward to the next generation of space telescopes, which will offer better opportunities to observe exoplanets. ‘The new telescopes are powerful. They use spectroscopy, which means that by looking at what kind of light is blocked in the planets’ orbit around their star, you can see how much water vapor there is. It can tell us something about the number of oceans on that planet, “he concludes.