Narrowing Down the Hunt for Infant Earths and Alien Life

First Posted: Dec 05, 2014 08:11 AM EST

Where should astronomers look for life on other planets? That's a good question. There are billions and billions of stars in the sky, so narrowing down the search is crucial for success. Now, scientists may have discovered where, and when, infant Earths are most likely to be found.

"The search for new, habitable worlds is one of the most exciting things human beings are doing today and finding infant Earth's will add another fascinating piece to the puzzle of how 'Pale Blue Dots' work," said Lisa Kaltenegger, one of the researchers, in a news release.

In order to more easily find worlds with the potential for life, the scientists created estimates for where one can find habitable infant Earths. As reference points, they assessed the maximum water loss for rocky planets that are at equivalent distances to Venus, Earth and Mars from our sun. In this case, the researchers found that during the early period of a solar system's development, planets that end up being in the habitable zone later on, when the star is older, can initially lose the equivalent of several hundred oceans of water or more if they orbit the coolest stars. However, even if a runaway greenhouse effect is triggered, the planet could still become habitable if water is later delivered to the planet after the runaway phase ends.

"Our own planet gained additional water after this early runaway phase from a late, heavy bombardment of water-rich asteroids," said Ramses Ramirez, one of the researchers. "Planets at a distance corresponding to modern Earth or Venus orbiting these cool stars could be similarly replenished later on."

What's interesting is that on young worlds the habitable zone is located further away from young stars than previously thought. This increased distance means that these infant planets should be able to be seen early on by the next generation of ground-based telescopes. Not only that, but it's possible that life could potentially begin on a planet during its sun's early phase and then life could either move to the planet's subsurface, or underwater, as the star's luminosity decreases.

The findings reveal a bit more about where scientists should look to find life on other planets. This, in turn, could help future research.

The findings are published in Astrophysical Journal Letters.

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