What did Isaac Newton provide that explained the 'why' behind Kepler's observations?

Answer

The formulation of the law of universal gravitation.

Newton's law of universal gravitation provided the physical underpinning, explaining that the Sun's mass dictates the paths and speeds of the planets, thus explaining why orbits were elliptical.

What did Isaac Newton provide that explained the 'why' behind Kepler's observations?

#Videos

How We Figured Out That Earth Goes Around the Sun - YouTube

sunEarthrotationheliocentrismProof