NASA's Kepler mission has confirmed the discovery of its first rocky planet, named Kepler-10-b. It's 1-point-four times the size of Earth, making it the smallest planet ever discovered outside our solar system. Team leaders at NASA'a Ames Research Center in California say it's also the first solid evidence of a rocky planet orbiting a star other than our sun.

The size of the exoplanet can be derived from periodic dips in brightness. Kepler's ultra-precise photometer measures the tiny decrease in a star's brightness that happen when a planet crosses in front of it. The distance between the planet and the star is calculated by measuring the time between successive dips as the planet orbits the star.

As a result of the analysis, that star orbited by the planet - Kepler-10 - is now one of the most well-characterized planet-hosting stars in the universe.