The mystery object is called 2014 UN271, and it’s currently 22 AU from the Sun (in which 1 AU is the average distance of Earth to the Sun), which means it has already passed the orbit of Neptune. The International Astronomical Union Minor Planet Center announced the detection on June 19. This object will travel another 11.1 AU before reaching its perihelion point (closest approach to the Sun) in 2031, after which 2014 UN271 will begin its long journey back to the Oort cloud. Measuring somewhere between 62 and 230 miles (100-370 kilometers) in diameter, 2014 UN271 is one of...