A comet so massive that it was initially misidentified as a dwarf planet is on its way in from the outer Solar System.

There’s no need to be concerned; C/2014 UN271 (Bernardinelli-Bernstein), as the comet is known, will pass just outside Saturn’s orbit. However, its large size and close proximity will provide a once-in-a-lifetime opportunity to study a pristine object from the Oort Cloud and learn more about the formation of the Solar System.

“We have the privilege of having discovered perhaps the largest comet ever seen – or at least larger than any well-studied one – and caught it early enough for people to watch it evolve as it approaches and warms up,” co-discoverer and astronomer Gary Bernstein from the University of Pennsylvania said earlier this year.