Oort Cloud
A theoretical, distant shell of icy bodies surrounding our solar system, thought to be the source of long-period comets like C/2023 A3, stretching up to 100,000 astronomical units from the Sun.
The Oort Cloud is a theoretical, vast shell of icy objects surrounding the solar system at a distance of up to 100,000 astronomical units, believed to be the source of long-period comets. Named after Dutch astronomer Jan Oort, it is hypothesized to consist of debris left from the formation of the solar system, ejected from the inner regions by the gravitational influence of giant planets.
What this means in real life
When a comet suddenly appears in Earth's night sky after thousands of years, astronomers believe it was knocked loose from the Oort Cloud by a passing star's gravity, sending it on a long journey toward the inner solar system.
What it isn’t
It is not a ring or disk like the asteroid belt or Kuiper Belt. The Oort Cloud is a spherical halo surrounding the entire solar system, not a flat plane, and contains far fewer, more distant objects.
Commonly misused online
Social media often conflates the Oort Cloud with the Kuiper Belt, treating them as the same thing. In reality, the Kuiper Belt is a distinct, closer region of icy bodies just beyond Neptune, while the Oort Cloud is a theoretical, much more distant sphere.