Rocky Alien Worlds May  Support Life

Need To Be Young 

As search for life in the universe

 continues, scientists already know it's not enough to find rocky planets in a star's habitable zone, the region where a planet can host liquid water

Liquid water is just the 

starting point Indeed, other factors, such as nitrogen, may play a role in a planet's habitability, as well as the ratio of land to sea.

A team of scientists suggests

 that one of the key characteristics of a life-supporting, rocky exoplanet is that it must be young — just a few billion years old at most. 

To support life, a planet needs 

enough heat to power a carbon cycle, which is typically created due to the radioactive decay of elements such as uranium and thorium. 

Lead author Cayman Unterborn, a

research scientist at the Southwest Research Institute said "Exoplanets without active degassing are more likely to be cold, snowball planets,"    

That radioactive decay, in turn,

 causes volcanic degassing — the release of gasses held within a planet into the atmosphere through volcanoes — on the surface of a planet.

Degassing contributes CO2 to

  the atmosphere and continues the carbon cycle. But older planets might have consumed their radioactive resources and thus may not be able to retain their heat

Earth Tells Us To 'GO' In   From Space

Weird Cloud Message Seen