evidence: A grazing encounter between the Solar System and a passing star could once have changed Earth's orbit enough to wreak havoc on the climate, new research has found. [...] "One reason this is important is because the geologic record shows that changes in the Earth's orbital eccentricity accompany fluctuations in the Earth's climate," Kaib says. [...] The Solar System is relatively stable, but orbits can be tweaked, and fairly easily. Earth's orbit, for instance, is regularly tugged about by the giant planets, which enact long-period changes on its orbital eccentricity, axial tilt, and precession.