There doesn't need to be any physical impactors for there to be a significant effect on climate and life. Ice ages can start and end due to tiny changes in the

There doesn't need to be any physical impactors for there to be a significant effect on climate and life. Ice ages can start and end due to tiny changes in the Earth's orbital wobble. https://phys.org/news/2016-12-ice-ages-linked-earth-orbitbut.html https://phys.org/news/2016-12-ice-ages-linked-earth-orbitbut...