Comets probably come from the Oort Cloud and the Kuiper Belt.
These aren’t places in a fairy tale.
The Oort Cloud, named after astronomer Jan Oort, is theoretically a loose shell of leftover matter from the solar system’s formation.
Approximately 98,000 astronomical units (AUs) thick, it encircles the Sun beginning about 2,000 AUs away.
The Kuiper Belt, theorized by astronomer Gerard Kuiper, is purported to be a band of planetesimals from the solar nebula that lies just beyond Neptune’s orbit.
Some comets may originate there.
Most comets are believed to come from the Oort Cloud, an outlying area of the solar system.
Short-period comets may originate in the Kuiper Belt, a theoretical “junkyard” of celestial debris just beyond the orbit of Neptune.