Comets have unstable orbits because they are affected by the gravitational pull of other celestial bodies. As they travel through the solar system, they can be pulled off course by planets or other large objects, causing their orbits to change over time.
Comets get their unstable orbits from the gravitational forces of the planets in our solar system. These forces can cause the comet's orbit to become elongated or even change direction, making their orbits unpredictable and unstable.
While scientists can make predictions about the general path of a comet, the specific details of their orbits are difficult to predict due to their instability. Factors such as outgassing and collisions with other objects can also affect the comet's trajectory, making it challenging to accurately predict their orbits.
The length of time a comet's orbit remains unstable can vary greatly. Some comets may have unstable orbits for only a few years, while others can have unstable orbits for hundreds or even thousands of years.
There is currently no known way to stabilize the orbits of comets. Their unstable orbits are a natural result of the gravitational forces in our solar system, and attempting to alter their paths would require immense amounts of energy and technology that is currently beyond our capabilities.