Fig. 2. The habitable zone.
The light blue region depicts the “conventional” habitable zone for planets with nitrogen, carbon dioxide and H20 atmospheres. The yellow region shows the habitable zone as extended inward for dry planets, as dry as 1% relative humidity. The outer darker blue region shows the outer extension of the habitable z one for hydrogen-rich atmospheres and can extend even out to free-floating planets with no host star. The solar system planets are shown with images. Known exoplanets are shown with symbols [here, planets with a mass or minimum mass less than 10 Earth masses or a radius less than 2.5 Earth radii taken from . Science Magazine/Seager