American scientists have discovered evidence that two million years ago the solar system passed through a dense cloud of cold interstellar gas, which could have changed the Earth's climate, as well as increased its bombardment with cosmic rays.
On Monday, June 10, the Boston University press service quoted Harvard University professor Abraham Loeb as saying: “The interstellar environment outside the solar system usually has a rare and weak impact on terrestrial life. We have discovered possible evidence that the passage of the solar system through... A dense cloud of gas led to Earth being exposed for an unusually long period of time to cosmic rays and hydrogen atoms.
The researchers reached this conclusion by studying how the solar system interacts with the regions surrounding the Milky Way Galaxy as it travels around the center of the galaxy. Currently, as the scientists note, “we are inside a so-called local bubble, a relatively empty region where there are a number of small, but dense, accumulations of neutral gas and dust.”
Astronomers calculated the speeds and directions of movement of these clouds of gas and dust and discovered evidence that one of these accumulations of matter, which the researchers called the Lynx Local Cold Cloud (LLCC), was in the past on the path of the solar system. Our star system had the potential to pass through the tail of this gas cloud about two million years ago.
In this case, as scientists' calculations showed, the size of the heliosphere, a bubble of solar plasma that usually surrounds the entire solar system, should have decreased from the current 130 astronomical units (the average distance between the Sun and the Earth) to 0.22 astronomical units. As a result, all planets, including Earth, had to be outside the heliosphere, depriving them of protection from cosmic rays and hydrogen molecules from the interstellar medium, which are usually reflected by the Sun's magnetic field.
The arrival of these particles and molecules on Earth, based on the findings of the researchers, greatly affected the evolution of our ancestors, as well as the planet’s climate and the isotope ratios of some elements. In particular, this event explains the presence on Earth of an excess of iron 60 and plutonium 244, the presence of which astronomers attributed on our planet to nearby nova explosions. The researchers concluded that Earth's passage through the LLCC cloud provides a more plausible explanation for these isotopic anomalies.
The universe is very intriguing.
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