A Giant Interstellar Cloud May Have Once Enveloped Earth, Potentially Causing Ice Ages

Astronomers suggest this cold, dense cloud compressed our sun’s protective field between two and three million years ago, leaving the Earth exposed to cosmic material

Christian Thorsberg
Daily Correspondent

June 14, 2024



orange dust surrounds a bright star
Captured by the Hubble Space Telescope, the heliosphere of a young star, LL Orionis, collides with an interstellar medium of dust. A similar event with our own sun, researchers say, might have occurred between two and three million years ago. NASA / STScI / AURA


Some two million years ago, our human ancestors shared the Earth with the likes of mastodons, saber-toothed tigers and giant sloths. At that time, survival was anything but easy. For a long period ending only about 12,000 years ago, our planet withstood a series of harsh ice ages that saw global temperatures fluctuate, sea levels rise and fall as glaciers melted and re-froze, and plant and animal life shift from the poles toward the warmer equator.

The causes behind this tumultuous epoch have been debated for years. Scientists have considered volcanic eruptions, varying levels of atmospheric carbon dioxide, Earth’s tilt and volatile plate tectonics. Now, research published this week in the journal Nature Astronomy offers another hypothesis of cosmic proportions: that our solar system passed through a massive, interstellar cloud of dust and gas.

Typically, Earth and all our solar system’s planets are enveloped in a protective, giant bubble of plasma from the sun known as the heliosphere. Within this perhaps croissant-shaped region, the sun’s charged particles, known as solar wind, shield the planets from galactic radiation and the extreme weather of outer space.

But between two million and three million years ago, the researchers posit that an interstellar cloud compressed the heliosphere, temporarily leaving much of the solar system, including Earth, vulnerable.

More:
https://www.smithsonianmag.com/smart-news/a-giant-interstellar-cloud-may-have-once-enveloped-earth-potentially-causing-ice-ages-180984529/