Astronomers have made the rare and tantalizing discovery of an Earth-like exoplanet 40 light-years away that may be just a little warmer than our own world. The potentially-habitable planet, named Gliese 12 b, orbits its host star every 12.8 days, is comparable in size to Venus — so slightly smaller than Earth — and has an estimated surface temperature of 42 C (107 F), which is lower than most of the 5,000-odd exoplanets confirmed so far. That is assuming it has no atmosphere, however, which is the crucial next step to establishing if it is habitable.