Beyond the Planets
The solar system does not end at the outer orbits of the big planets. Pluto’s orbit carries it beyond the orbit of Neptune and Pluto is one of a number of objects that are thought to reside in the Kuiper Belt (alternative site), a doughnut-shaped ring, extending from about 30 to 50AUs. The New Horizons Mission is the only mission that has been designed to explore the Kuiper Belt, which is likely home to hundreds of thousands of icy bodies larger than 100 km across. The Kuiper Belt is also thought to contain an estimated trillion or more smaller icy bodies, which would become comets if they made there way into the inner solar system. Here is a depiction of what the Kuiper Belt looks like with respect to Sedna, a minor planet discovered in the outer reaches of the Solar system in 2003.
But don’t stop now, there is more. Beyond the Kuiper Belt lies a large cloud of other primarily icy bodies, called the Oort Cloud. This cloud is thought to extend to approximately 50,000 and 200,000 AU. We can abide by our convention of not presenting very large numbers if we switch units. That many AUs translates to between 0.8 and 3.2 light years. 3.2 lightyears is more than halfway to the nearest star, Alpha Centauri, which is 4.367 light years away from us. A proper scaled representation of our solar system, including the Oort cloud, looks something like this:
