Finding Earth-Like Exoplanets

In the abundance of exoplanets we've found so far, we've had our fingers crossed that we would find worlds with the two main characteristics that make our Earth unique: Being just the right distance from the sun and being just the right size.

A planet's distance from its sun determines the temperature of the planet, based on the radiation it receives from its star, and that temperature determines whether liquid water can exist on the planet in sufficient abundance to support life. The freezing and boiling points of water, therefore, determine the habitable zone for a star.

A planet's size helps determine what type of planet it is, and Earth-sized planets are more likely to be rocky, like our Earth.

Huffington Post keeps a running list of stories about Earth-like exoplanets, including...

• Kepler-186f, which orbits just at the edge of its star's habitable zone and is about 1.44 times the mass of Earth.
• "Super-Earth" Gliese-832c, which might have the right combination of characteristics to harbor Earth-like life.
• Kepler-62f, which may be covered entirely by a single ocean.