What orbital consequence for inner planets results from the increased gravitational tug-of-war without Jupiter?
Highly elliptical orbits leading to massive temperature swings.
If Jupiter had never formed, the gravitational interactions between the remaining smaller planets, such as Earth and Mars, would become significantly more volatile due to a lack of centralized dominance. This absence of a giant world managing the overall architecture leads to increased gravitational tug-of-war effects among the inner worlds. The primary result of this instability is the development of highly elliptical, or eccentric, orbits for the terrestrial planets. Extreme orbital eccentricity causes massive, rapid swings in the amount of solar energy absorbed by Earth, swinging wildly between runaway greenhouse conditions and deep freezes, which inherently hinders the possibility of sustained, complex biological development over geological timescales.
