The farthest known object orbiting our Sun is a ball of ice and rock unofficially called FarFarOut, which lies about 13 billion miles away right now, or 3.5 times the current distance to Plugo. Early estimates say it is roughly spherical and is 300 miles in diameter, making it a dwarf planet.
Another dwarf planet, Sedna, is closer to the Sun, but its orbit is more elliptical. At its farthest, it will be roughly 84 billion miles from the Sun. It is roughly 600 miles in diameter.
Another hop, skip, and a jump takes us to the heliopause, where the stream of particles emitted by the Sun collides with the galactic gases of interstellar space, forming a so-called “bow shock.” The boundary between the Sun’s influence and interstellar space may lie as much as 15 billion miles ahead of the Sun’s path through the galaxy, and more than 30 billion miles behind it.
Farther still is the Oort Cloud, believed to be the source of extremely long-period comets (Hale-Bopp, for instance). This dark, incredibly cold region awaits interstellar travelers at a minimum of about 200 billion miles from the Sun. Estimates of its outer edge range from about 50,000 to 200,000 times the distance from Earth to the Sun. The farther distance would be more than three light-years away, where the combined gravitational pull of the rest of the Milky Way Galaxy would overcome the Sun’s feeble gravity, stripping objects from the Oort Cloud.
LAST UPDATE: April 4, 2020