“This new object, 2014 UN271, is not just unusual, but radically exceptional among all known bodies in the Solar System to date.”
It may be 160 kilometers across, or up to 370, and it is falling in from the Oort Cloud to just beyond Saturn by 2031. That would make it the largest Oort Cloud object ever found. The Dark Energy Survey had it in images going back to 2014. Astronomers now get ten years of warning to watch it light up.