Comet Borisov 2I was spotted in our solar system, and it was only spotted once before. It has a sun-centered orbit that is not bound to the sun. It passed through our solar system at the end of Oct in 2019 and made its closest approach on Dec 8th of last year. The tail was 14 times the size of the Earth. It should be observable until Sept 2020, unless it fades or disintegrates unexpectedly.