Final answer:
TNOs are part of the Kuiper belt, extending beyond Neptune, and are a key source of many comets. This area of space allows for a greater understanding of solar system and is home to numerous celestial bodies, including dwarf planets.
Step-by-step explanation:
TNOs are a part of what is called the Kuiper belt, a large area of space beyond Neptune that is also the source of many comets. The concept of Trans-Neptunian Objects (TNOs) is a fundamental aspect of understanding our solar system's outer regions and the materials contained therein. These objects, found in the cold, dark regions beyond Neptune, include dwarf planets like Pluto, Eris, Makemake, and Haumea, as well as a multitude of smaller bodies that number over a thousand.
The Kuiper belt itself extends out to about 50 Astronomical Units (AU) from the Sun. This region is also a significant source of short-period comets, which originate in the Kuiper belt and are possibly influenced by Neptune's gravitational forces to enter the inner solar system. Beyond the Kuiper belt lies another hypothesized frontier, the Oort Cloud, which is thought to be the source of long-period comets.
Both these regions help astronomers learn more about the early solar system and the formation of the planets and other celestial bodies.