Two million years ago, the solar system encountered a dense interstellar cloud that may have significantly influenced Earth’s climate by compressing the heliosphere and exposing the planet to high levels of cosmic radiation and galactic rays. (Artist’s concept.) Credit: SciTechDaily.com
New astrophysical research highlights a significant cosmic event two million years ago when the solar system passed through a dense interstellar cloud. This possibly altered Earth’s climate by exposing it to enhanced cosmic radiation, supported by increased isotopes found in geological records.
Earth was a very different place around two million years ago, with our early human ancestors living alongside saber-toothed tigers, mastodons, and enormous rodents. And, depending on where they were, they may have been cold: Earth had fallen into a deep freeze, with multiple ice ages coming and going until about 12,000 years ago. Scientists theorize that ice ages occur for a number of reasons, including the planet’s tilt and rotation, shifting plate tectonics, volcanic eruptions, and carbon dioxide levels in the atmosphere.
But what if drastic changes like these are not only a result of Earth’s environment, but also the sun’s location in the galaxy?
Impact of the Sun’s Galactic Journey
In a new paper published today (June 10) in Nature Astronomy, lead author and astrophysicist Merav Opher—an astronomy professor at Boston University and fellow at Harvard Radcliffe Institute— found evidence that some two million years ago, the solar system encountered an interstellar cloud so dense that it could have interfered with the sun’s solar wind. Opher and her co-authors believe this shows that the sun’s location in space might shape Earth’s history more than previously considered.
Heliosphere’s Role in Earth’s Protection
Our whole solar system is swathed in a protective NASA calls a “a giant bubble.” It protects us from radiation and galactic rays that could alter SHIELD (Solar wind with Hydrogen Ion Exchange and Large-scale Dynamics) DRIVE Science Center are now exploring the effect it could have had on Earth’s radiation, as well as the atmosphere and climate.
“This is only the beginning,” Opher says. She hopes that this paper will open the door to much more exploration of how the solar system was influenced by outside forces in the deep past and how these forces have in turn shaped life on our planet.
Reference: “A possible direct exposure of the Earth to the cold dense interstellar medium 2–3 Myr ago” 10 June 2024, Nature Astronomy.
DOI: 10.1038/s41550-024-02279-8
This research was supported by NASA.
Discussion about this post