The Milky Way is teeming with planets that have continents and oceans like Earth

According to a new study from the University of Copenhagen, Earth, Venus, and March were created from small particles of dust containing ice and carbon. The discovery opens up the possibility that the Milky Way can be filled with aquatic planets.

Astronomers have long searched the vast universe in hopes of discovering extraterrestrial civilizations. But for a planet to have life, liquid water must be present. The odds of this discovery scenario seemed impossible to calculate as it was assumed that planets like Earth would get their water by chance if a large ice asteroid hit the planet.

Now, researchers at the GLOBE Institute at the University of Copenhagen have published a revealing study, indicating that water can be present during the very formation of a planet. According to the study’s calculations, this is true for Earth, Venus and Mars.

“All of our data suggests that water was part of the earth’s building blocks from the start. And since the water molecule is common, there is a reasonable probability that it applies to all planets in the Milky Way. The decisive point in knowing whether liquid water is present is the distance between the planet and its star, ”explains Professor Anders Johansen of the Center for Star and Planet Formation, who led the study published in the journal Science Advances.

Are all planets formed by ice?

Using a computer model, Anders Johansen and his team calculated how quickly planets form and from which building blocks. The study says they were millimeter-sized dust particles of ice and carbon – known to orbit all of the young stars in the Milky Way – which 4.5 billion years ago formed increased in the formation of what would later become Earth.

“At the point where the Earth reached one percent of its current mass, our planet grew by capturing masses of pebbles filled with ice and carbon. The Earth then grew faster and faster until, after five million years, it became as large as we know it today. Along the way, the surface temperature has risen sharply, causing the ice in the pebbles to evaporate down towards the surface so that today only 0.1% of the planet is water. , even though 70% of the Earth’s surface is covered with water, ”says Anders Johansen, who, with his research team in Lund ten years ago, put forward the theory that the new study now confirms.

The theory, called “pebble accretion”, is that the planets are formed by pebbles that clump together, and the planets get bigger and bigger.

Anders Johansen explains that the water molecule H2O is found everywhere in our galaxy, and therefore the theory opens up the possibility that other planets formed in the same way as Earth, Mars and Venus.

“All of the planets in the Milky Way can be formed by the same building blocks, which means that planets with the same amount of water and carbon as Earth – and therefore potential places where life can be present – are frequently occur around other stars in our galaxy, provided the temperature is right, ”he says.

Good chances for the emergence of life

If the planets in our galaxy had the same building blocks and temperature conditions as Earth, there is also a good chance that they have roughly the same amount of water and continents as our planet.

Professor Martin Bizzarro, co-author of the study, says:

“With our model, all planets receive the same amount of water, which suggests that other planets may not only have the same amount of water and oceans, but also the same amount of continents as here on Earth. It offers good opportunities for the emergence of life, ”he says.

If, on the other hand, the amount of water present on the planets was random, the planets could be very different. Some planets would be too dry to develop life, while others would be completely covered with water.

“A planet covered with water would of course be good for marine beings, but would offer less than ideal conditions for the formation of civilizations capable of observing the universe,” says Anders Johansen.

Anders Johansen and his research team are eagerly awaiting the next generation of space telescopes, which will provide much better opportunities to observe exoplanets orbiting a star other than the Sun.

“The new telescopes are powerful. They use spectroscopy, which means that by observing what kind of light is blocked from the orbit of the planets around their star, you can see how much water vapor there is. This can tell us something about the number of oceans on this planet, ”he says.

Reference: “A pebble accretion model for the formation of terrestrial planets in the solar system” by Anders Johansen, Thomas Ronnet, Martin Bizzarro, Martin Schiller, Michiel Lambrechts, Åke Nordlund and Helmut Lammer, February 17, 2021, Scientific advances.
DOI: 10.1126 / sciadv.abc0444