LIKE EARTH, BUT HOTTER

KEPLER-78B

At 1.2 times bigger than Earth and 1.8 times heavier with an almost identical density to our planet, Kepler-78b is similar to Earth – especially since it is likely to have been built from rock and iron. However, at 2,000 degrees Celsius (3,600 degrees Fahrenheit) that’s where the similarities end. You’d be hard pushed to find life as we know it on its surface, in fact this world shouldn’t really exist at all.

Circling its Sun-like star at around 40 times closer than Mercury orbits our Sun, Kepler-78b completes a year in only 8.5 hours and – according to how astronomers have visualised its surface – is a hellish molten world. As we currently understand it, our models of planet formation argue that this scorching lava world could never have formed so close to its star and it certainly could never have moved there. What’s more, the fact that it continues to orbit its star without succumbing to gravitational tides is causing astronomers to wonder if they have chanced upon a new class of planet.