Climate Change and Human Evolution from the Passage of the Solar System through a Cold Cloud 2-3Myrs ago

There is overwhelming geological evidence from 60Fe and 244Pu isotopes that Earth was in direct contact with the interstellar medium (ISM) 2-3 Myr ago.

The local interstellar medium is home to several nearby cold clouds. Here we show that if the solar system passed through a cloud such as Local Leo Cold Cloud, then the heliosphere which protects the solar system from interstellar particles, had shrunk to a scale smaller than the Earth’s orbit around the Sun (0.22 AU). Using a magnetohydrodynamic simulation that includes charge exchange between neutral atoms and ions, we show that during the heliosphere shrinkage, Earth was exposed to a neutral hydrogen density of up to 3000cm−3. This could have had drastic effects on Earth’s climate and potentially of human evolution at that time, as suggested by previous data.

Merav Opher, Abraham Loeb

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2202.01813 [astro-ph.EP] (or arXiv:2202.01813v1 [astro-ph.EP] for this version)
Submission history
From: Merav Opher
[v1] Thu, 3 Feb 2022 19:38:09 UTC (1,545 KB)
https://arxiv.org/abs/2202.01813
Astrobiology,