Final answer:
The force estimated for the student's jump is equal to Earth's gravitational force on him due to Newton's third law, but Earth's large mass means its resulting acceleration is negligible.
Step-by-step explanation:
The magnitude of the force that the daredevil astronomy student would estimate for his jump, as dictated by Newton's third law of motion, is equal in size to the gravitational force exerted on the student by the Earth. This is because for every action, there is an equal and opposite reaction. The Earth's gravitational force on the student is significant and always acting, making even a small fall potentially dangerous. Yet due to the enormous mass of the Earth, any acceleration it experiences due to its gravitational attraction with the student is minuscule and undetectable. Newton's universal law of gravitation helps calculate the exact force values for such interactions, which also illustrates significant differences when comparing different mass interactions, such as the gravitational influence of Jupiter on a baby versus that of the baby's father.