Catalog of Habitable Planets
The idea of what makes a planet “habitable” is one of temperature, distance from its parent star, composition, etc. It’s not really one of utility, i.e. “actually being able to go live there”.
The search for exoplanets via NASA’s Kepler project and others has perhaps not discovered life-rich alien worlds (the equipment they use couldn’t do that if they tried), but it has reinforced the idea that there are a TON of planets out there. Planets, like or unlike our own, are very common.
The Planetary Habitability Laboratory at Puerto Rico’s Aricebo observatory (the big crater telescope from Contact) put together this catalog of potentially habitable known exoplanets ranked by their “Earth Similarity”. Visit the link for a load more details.
As our techniques and equipment advance, this list will surely grow by leaps and bounds. It doesn’t mean that any of them will harbor extraterrestrial life, but it reminds us that while the scientific characteristics of our home might not be uncommon, the ability for one species on Earth to search for others like it surely is something special.