When it comes to habitability, Earth may not provide the best example. Indeed, astrobiologists are saying we should look for planets that are more hospitable to life than ours — a new class of objects they're calling superhabitable worlds. They even know where we should look.
In the search for extraterrestrial life, astrobiologists are increasingly moving beyond the standard stellar habitable zone hypothesis (HZ). As a recent study noted, life could emerge on planets and moons outside the so-called Goldilocks Zone, what the authors have dubbed the subsurface habitable zone. But more to the point, just because a planet can host liquid water on its surface — the criteria for habitability — doesn't mean it can also foster life.