• 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.