Paper published in Nature:

A possible direct exposure of the Earth to the cold dense interstellar medium 2–3 Myr ago

Cold, dense clouds in the interstellar medium of our Galaxy are 4–5 orders of magnitude denser than their diffuse counterparts. Our Solar System has most likely encountered at least one of these dense clouds during its lifetime. However, evidence for such an encounter has not been studied in detail yet.

New study finds Earth collided with dense interstellar cloud, possibly affecting life on planet.

Call it the Milky Way mystery. Evidence of a long-ago collision involving the Earth was there in the form of specific radioactive isotopes deposited across the Earth and Moon. There were, however, skeptics.

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NewScientist – Cosmic cloud exposed Earth to interstellar space 3 million years ago.

The protective bubble around the sun retreated dramatically after colliding with a freezing interstellar cloud, leaving much of the solar system exposed to radiation that may have shaped our evolution, a study suggests.

Between 2 million and 3 million years ago, the solar system encountered turbulence on a galactic scale, colliding with a dense interstellar cloud that may have altered both the climate and evolution on Earth.

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Solar system’s heliosphere may be croissant-shaped – study.

for The Jerusalem Post. Published: August 9, 2020.
These findings could have major implications on the search for habitable planets outside the solar system.

Héliosphère – Aux frontières de notre cocon cosmique

By Benoît Rey for Science & Vie, March 2022

Voyager spacecraft detects ‘persistent hum’ past solar system

By Charlie McKenna, Boston Globe Correspondent, updated May 17, 2021
Illustration above (NASA/JPL-CALTECH) depicts one of NASA’s twin Voyager spacecraft. Both Voyagers have entered interstellar space, or the space outside our Sun’s heliosphere.

Visualizing the Heliosphere, Our Solar System’s Protective Bubble

By Art Jahnke, for The Brink – Pioneering Research from Boston University, February 21, 202o. BU astrophysicist Merav Opher will lead a new NASA DRIVE (Diversity, Realize, Integrate, Venture, Educate) Science Center aimed at developing a predictive model of the heliosphere. Photo by Cydney Scott.