Tweaking The Habitable Zone

A new study makes slight adjustments in the definition of the habitable zone around a star-- the area where liquid water, and therefore possibly life, could exist on the surface of a planet.  The adjustments,while small, do tend to exclude some exoplanets previously thought to be within their stars' zones, while a few exoplanets previously thought outside their zones are now inside.

Oddly, under the new definition, Earth is on the inner edge of the Sun's habitable zone.  Given that life has existed uninterruptedly on Earth for over three billion years, and postulating that the habitable zone likely changes over the lifetime of a star, perhaps the new definition needs further tweaking.

Of course, the results of the study will only help astronomers decide where they might look for life.  The actual range of life in the cosmos may well be quite different.