The Sun’s Trajectory in the Last 10 Million years

The Anthropogenic climate crisis is a central challenge facing humanity today. Crises like this are not new, in fact Earth’s history has been marked by periods of rapid climatic change associated with dramatic consequences for the biosphere and its inhabitants. However, the drivers of these events are often unclear and are generally attributed to a few types of phenomena. The impacts of astronomical phenomena on climate and the evolution of biological systems have only been considered minimally. The Sun moves large distances (~19pc/Myr pc/Myr) through the quite variable Interstellar Medium. There is geological evidence from 60Fe and 244Pu isotopes that Earth received interstellar material about 2-3 Myr ago and 7 Myr ago. These isotopes were interpreted evidence for a nearby supernova, however that has been cast into doubt. In this talk I will discuss our new research indicating the encounter of Earth with massive cold cloud in Local Ribbon of Cold Clouds, 3 Myr ago and with the edge of the Local Bubble 7 Myr ago. Both encounters shrinked the Sun’s protective bubble—the heliosphere—to within Earth’s orbit exposing Earth to a cold dense interstellar medium. I will discuss the possible terrestrial consequences to climate and to biological evolution.

Видео The Sun’s Trajectory in the Last 10 Million years канала CfA Colloquium