What important discovery was made by Edmond Halley and Alex clairaut using newtons ideas of mathematics and gravity?

Edmond Halley and Alexis Clairaut made significant contributions to the understanding of the orbits of comets and the shape of the Earth using Newton's ideas of mathematics and gravity. Halley famously predicted the return of Comet Halley by applying Newton's laws of motion and universal gravitation. Clairaut extended this work by using Newtonian principles to determine that the Earth is not a perfect sphere but an oblate spheroid, confirming that the planet's equatorial diameter is larger than its polar diameter due to its rotation. These discoveries laid the foundation for modern celestial mechanics and geophysics.