Jupiter
The grand tack hypothesis explains another mystery of the Solar System. Mars should have been larger than Earth but is instead only  of this size. On Jupiter's grand tack, it cleared the area where Mars orbits today. After it left, the material remaining was only enough to form a small planet and a low-mass asteroid belt. Although the hypothesis has not been absolutely proven, there is no other competing explanation why the Solar System's giant should be so far from its star, and Mars so small.