Psychedelic Pluto

A four-planet system orbiting the star Kepler-223 in the constellation Cygnus is actually a rarity: Its planets, all miniature Neptunes nestled close to the star, are orbiting in a unique resonance that has been locked in for billions of years. For every three orbits of the outermost planet, the second orbits four times, the third six times and the innermost eight times.

NASA’s New Horizons spacecraft made a historic New Year’s encounter with an object nicknamed Ultima Thule in the Kuiper Belt a billion miles beyond Pluto. The probe passed around 3,500 kilometres from the mysterious object at 0533 GMT on New Year’s Day, making it the most distant Solar System body ever explored up close.

A subsurface ocean lies deep within Saturn’s moon Dione, according to new data from the Cassini mission. Two other moons of Saturn, Titan and Enceladus, are already known to hide global oceans beneath their icy crusts. Researchers believe that Dione’s crust floats on an ocean several tens of kilometres deep located 100 kilometres below the surface.