The Farthest Object In The Solar System

When we think of the solar system, we generally view it as the sun and the planets, yet the solar system actually extends much farther beyond the boundaries of the planets. In fact, there is more space beyond the orbit of the planets than there is within them. The farthest planet in the solar system is Neptune, which orbits the sun at a distance of 2.8-billion miles (4.5-billion kilometres). Beyond Neptune, however, are two more regions of our solar system: the Kuiper Belt and the Oort Cloud. The Kuiper Belt, located just beyond Neptune, extends to a distance of 5-billion miles (8.2-billion kilometres) from the sun. Beyond the Kuiper Belt is the Oort Cloud, the largest region of the solar system. The true size of the Oort Cloud remains unknown, yet some estimates place its size at around one light year across. To date, the farthest object ever discovered in the solar system is a tiny object called Farfarout, which orbits the sun at a distance of 12.3-billion miles (19.8-billion kilometres).


Farfarout illustration
Artisitc illustration of Farfarout. Image credit: NOIRLab

Farfarout is the farthest known object in the solar system, and it belongs to a class of object called a centaur. A centaur is an astronomical object that has characteristics similar to asteroids, comets, and dwarf planets. They can be thought of as objects that exist in a state between that of an asteroid and a dwarf planet. Since Farfarout is located so far away, it is difficult to determine anything about it. Even its size remains unknown, yet most estimates place its size around 250-miles (400-kilometres) across. Despite its small size and distance, however, it has a fairly high brightness, which suggests that its surface is covered in ice. Since Farfarout is located so far away from the sun, it takes a long time to complete a single orbit. Its orbital period has been determined to be around 1,000 years long. 

Is There Anything Beyond Farfarout?

Oort Cloud
Visual illustration of the solar system and Oort Cloud. Image credit: NASA

Farfarout is the farthest known object in the solar system, yet there are very likely countless objects beyond its orbit. The outer regions of the Oort Cloud contain billions of comets and other forms of debris, yet they are simply too far away to be seen with a telescope, and so Farfarout claims the title of farthest known object in the solar system. Interestingly, since the Oort Cloud cannot be observed directly, its existence is predicted through indirect means, most notably the orbital paths of comets that happen to make their way through the inner solar system.