Two ‘second Earths’ more similar to our planet than first thought – could harbour alien life

A pair of planets dubbed “second Earths” are more closely related to our planet than first thought.

Kepler-186f and Kepler-62f – located approximately 500 and 1,200 light years away respectively are two exoplanets that could potentially harbour alien life.

They are both within the “habitable zone” of their parent star, similar to Earth’s location in our own solar system.

A new study from the Georgia Institute of Technology has used simulations to study the spin axis of the exoplanets. This, in turn, has given astronomers more of an idea about possible seasons and climate of the distant world.

The axis of a rotating planet will determine how the sunlight strikes its surface.

Exoplanet Kepler 62f, which orbits a star 1,200 light years from Earth
Exoplanet Kepler 62f, which orbits a star 1,200 light years from Earth

The researchers suggest that Kepler-186f’s tilt is very stable, much like Earth’s, which makes it likely that it has regular seasons and a stable climate.

“Mars is in the habitable zone in our solar system, but its axial tilt has been very unstable – varying from zero to 60 degrees,” said Georgia Tech Assistant Professor Gongjie Li, who led the study together with graduate student Yutong Shan from the Harvard-Smithsonian Center for Astrophysics.

“That instability probably contributed to the decay of the Martian atmosphere and the evaporation of surface water.”

Kepler-186f is the first Earth-size planet discovered in the potentially 'habitable zone' around another star, where liquid water could exist on the planet's surface
Kepler-186f is the first Earth-size planet discovered in the potentially ‘habitable zone’ around another star, where liquid water could exist on the planet’s surface

To put that into context, the axial tilt of the Earth is very mild. It moves between 22.1 and 24.5 degrees, going from one extreme to the other every 10,000 years or so.

“Our study is among the first to investigate climate stability of exoplanets and adds to the growing understanding of these potentially habitable nearby worlds,” said Li.

“I don’t think we understand enough about the origin of life to rule out the possibility of their presence on planets with irregular seasons.”

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Exoplanets – those outside our solar system – can be found by registering dips in light caused by the shadow of the planet as it crosses in front of its host star.

These dips are indications of exoplanets, but must be examined much closer to validate the candidates are actually exoplanets.

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