NASA's Kepler mission, tasked with the illustrious mission of finding an Earth 2.0 for humankind, has located the first Earth-sized planets orbiting a star outside our solar system.
The two worlds, Kepler 20e and Kepler 20f, are too close to their parent star (their sun-equivalent) to be in the habitable zone - where liquid water could exist on their surfaces - but they are the smallest exoplanets ever confirmed in an Earth-type location.
Earlier this month, Kepler spotted the first Earth candidate in a habitable zone, Kepler 22b, but that rock is 2.4 times the size of our planet.
Both 20e and 20f, which are thought to be rocky worlds, are the next milestone because they're the right size.
Unfortunately, due to their proximity to their system's parent star and their short orbital periods - 20e orbits the parent star every 6.1 days and 20f every 19.6 - they are hot furnace-like planets completely inhospitable to any form of life.
The temperature on 20f, with balmy highs of 800° Fahrenheit (427°C), is similar to the weather on Mercury, while the climate on 20e, at more than 1,400°F (760°C), would melt glass.
