How Interstellar Clouds Can Affect Earth's Climate

Astrophysicist Merav Opher found evidence that the solar system may have passed through interstellar clouds 2 million years ago, and interfered with the sun's solar wind. The Milky Way is wrapped in a protective plasma that spreads out from the sun, known as the heliosphere. The heliosphere is made of solar wind, which is a constant flow of charged particles. The heliosphere is what protects planets from harmful radiation.

The Heliosphere Squeeze

Opher discovered that a cold cloud, a region in space filled with cold gas and dust, squeezed the heliosphere, making it smaller. This means that planets, like the Earth, were temporarily moved out of the protective bubble of the heliosphere and exposed to more cosmic radiation than usual.

Mapping the Past

Utilizing complex computer models, Opher and her colleagues have visualized the position of the sun 2 million years ago. Alongside this, they also mapped the Local Ribbon of Cold Clouds, a string of highly dense interstellar clouds mostly composed of hydrogen atoms. One of the clouds, called the Local Lynx of Cold Cloud, was super close to colliding with the heliosphere. Theoretically, if this had occurred, gas, dust, plutonium, and iron would mix in the interstellar medium. These atomic elements would have no trouble reaching the unprotected Earth because the heliosphere would be squeezed by the interstellar clouds. This information aligns with evidence of increased iron and plutonium in the ocean and Antarctic snow during that time period.

Looking Forward

The research is groundbreaking because it is the first to show that cosmic neighbors beyond our solar system can affect Earth's climate and atmospheric chemistry. Opher predicts that Earth will likely encounter more interstellar clouds in about another million years.