The Bernardinelli-Bernstein comet last came close to the Sun at 18 AU around 3.5 million years ago, but the next approach will be at roughly 11 AU.
One of the largest comets ever discovered in space — the Bernardinelli-Bernstein comet (or C/2014 UN27) — will be paying a visit to Earth’s solar system in 2031 while on its closest approach to the Sun. Predominantly made out of ice, rock, and dust, the space community also has a few other names for comets such as ‘dirty snowballs’ and ‘cosmic snowballs’ due to their peculiar structure as they orbit around a star on their strongly elliptical orbit and leave behind a trail that can be hundreds of thousands of miles in length.
Known to float in the vastness of space for thousands of years, a comet meets its demise when it gets a little too close to a star, causing the heat generated from the star to vaporize its icy body. Sometimes, a comet can also be torn apart when nearby cosmic objects with a strong gravitational pull cause the solid nucleus to break into multiple pieces. Even though the number of comets known to scientists currently stands at less than four thousand, it has been theorized that there are billions out there in the Kuiper Belt and the distant Oort cloud.