The correct answer is B. They were able to find the orbit of a comet and predict the year of its return.
Edmond Halley was a British astronomer, geophysicist, mathematician, meteorologist, and physicist. Alexis Clairaut was a French astronomer, geophysicist, mathematician.
They were friends with Isaac Newton that before, had built a new theory of universal gravitation.
With this new theory, Newton calculated the orbit of the Great Comet of 1680. Later, Halley used Newton’s theory to calculate the orbits of several comets - even some that were in ancient records -. The thing is: Halley noticed that some comets had similar orbits, which led him to suggest that some comets may be periodic and that they may be moving along very elongated ellipses. This way he forecasted the comets return in a period of 76 years.
Since then, the comet has carried Halley’s name.
