The Milky Way Could Be Home to Earth-Like Planets That Feature Continents and Oceans

In their new study, researchers out of the University of Copenhagen note that the presence of water is key for habitable conditions.

While new discoveries in the galaxy seem to happen more often these days, the inner workings of our solar system are still a mystery—especially when it comes to finding other habitable planets for humans. That moment could be here soon, though, and it's all thanks to new research from University of Copenhagen researchers. In their study published in the journal Science Advances, the team noted that the Milky Way could actually house Earth-like planets that feature oceans and continents. Previous research explained that the planets in the galaxy, like ours, all had water after an ice asteroid hit. The new findings uncover that Earth got water from masses of ice- and carbon-filled pebbles that originally surrounded the stars in outer space.

"All our data suggest that water was part of Earth's building blocks, from the beginning. Because the water molecule is frequently occurring, there is a reasonable probability that it applies to all planets in the Milky Way," said Anders Johansen, the leader of the study from the GLOBE Institute, in a statement. Plus, the authors' computer model led them to believe that the "building blocks" came about and grew as big as Earth is today after millions of years. "The decisive point for whether liquid water is present is the distance of the planet from its star," Johansen added. "Up to the point where Earth had grown to one percent of its current mass, our planet grew by capturing masses of pebbles filled with ice and carbon. Earth then grew faster and faster until it became as large as we know it today. This occurred over five million years."

long exposure of milky way galaxy in namibia
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The conditions ultimately created the change on the planet. "At some point, the temperature on the surface rose sharply, causing the ice in the pebbles to evaporate on the way down to the surface so that, today, only 0.1 percent of the planet is made up of water, even though 70 percent of Earth's surface is covered by water," Johansen said. "All planets in the Milky Way may be formed by the same building blocks, meaning that planets with the same amount of water and carbon as Earth occur frequently around other stars in our galaxy, provided the temperature is right. These could be potential places where life may be present."

Researchers plan to use space telescopes to study the amount of water vapor that's present on exoplanets orbiting a star. In the meantime, scientists are also considering the fact that there could be other life on these planets, too. "With our model, all planets get 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 as here on Earth. It provides good opportunities for the emergence of life," Martin Bizzarro, a professor and the co-author of the study, said. "A planet covered by water would of course be good for maritime beings, but would offer less than ideal conditions for the formation of civilizations that can observe the universe," Johansen added.

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