1. A New Model for Habitable Zones

    Habitable Zone Estimates

    The graphic shows habitable zone distances around various types of stars. Some of the known extrasolar planets that are considered to be in the habitable zone of their stars are also shown. On this scale, Earth-Sun distance is 1 astronomical unit, which is roughly 150 million kilometers. Credit: Chester Herman

    Astrobiologists supported in part by the NASA Astrobiology Institute have developed an updated model for determining whether or not extrasolar planets lie within the 'habitable zone’ of their host stars. The new model shows that the habitable zone may sit further away from a star than previously thought.

    The findings have some interesting implications for studying solar systems including our own. For instance, the Earth might orbit closer to the inner edge of the Sun’s habitable zone than scientists once believed. In addition, extrasolar planets previously thought to be within their star’s habitable zone may, in fact, not be.

    According to the researchers, the study also indicates that the Earth is approaching a “moist greenhouse” state. This could result in our climate shifting to a Venus-like “runaway greenhouse” that could spell disaster for our future on Earth.

    The study was published in The Astrophysical Journal .

    Source: [Penn State]