How to find an infant Earth

New research from Cornell University shows where - and when infant Earths are most likely to be found.

The team found that the Habitable Zone - the orbital region where water can be liquid on the surface of a planet and where signs of life in the atmosphere can be detected with telescopes - turns out to be located further away from the young stars these worlds orbit than previously thought.

"This increased distance from their stars means these infant planets should be able to be seen early on by the next generation of ground-based telescopes," said research associate Ramses M. Ramirez from Cornell University's Institute for Pale Blue Dots.

Moreover, it is possible that life could begin on a planet during its Sun's early phase and then that life could move to the planet's subsurface (or underwater) as the star's luminosity decreases, the authors noted.

The paper by Ramirez and director Lisa Kaltenegger offers estimates for where one can find habitable infant Earths.

They also 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 - initially can 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 - when a planet absorbs more energy from the star than it can radiate back to space, resulting in a rapid evaporation of surface water - a planet could still become habitable if water is later delivered to the planet, after the runaway phase ends," Kaltenegger added.

"Our own planet gained additional water after this early runaway phase from a late, heavy bombardment of water-rich asteroids," Ramirez said.

The paper is forthcoming in the journal Astrophysical Journal Letters.