...and do tens of billions of potentially habitable extrasolar planets mean that Earth is not unique?

*Big Picture Science Radio Show: It's Habitable Forming
Evidence suggests a subsurface lake on Mars, prompting scientists
to use the “h” word. Could the Red Planet be habitable?

While we wait – impatiently – for a confirmation of this result,
we consider the recipe for habitable worlds.
Dive into a possible briny lake on Mars … protect yourself from
the methane-drenched rain on Titan … and cheer on the
missed-it-by-that-much-planets, the asteroids Ceres and Vesta.
And do tens of billions of potentially habitable extrasolar planets
mean that Earth is not unique?
*source of information
http://bigpicturescience.org/episodes/its-habitable-forming