Answer:
the formation of a solar system
Explanation:
Models represent objects, events, and processes in the real world.
Models are often used when an object, event, or process
occurs too slowly or too quickly;
is too small or too large;
is too complicated or too dangerous.
Out of all the scientific processes and objects listed, the only one that could not be directly observed is the formation of a solar system. Scientists can use large telescopes to see some distant solar systems in the process of formation, but the process takes such a long period of time that it cannot be fully observed by a person.
