The interstellar cloud may have influenced Earth's climate

Led by astrophysicist Merav Ofer, researchers reconstructed the past orbit of the solar system using complex computer models. They found that a collision with an interstellar cloud known as the “local lynx of cold clouds” would likely severely distort the heliosphere – the solar system's protective layer.

This may have led to the planets of the solar system being directly exposed to the interstellar medium, which greatly affected Earth's climate. So they could be in a trade magazine Nature astronomy The published results explain why the Earth is going through an ice age at this time.

After colliding with an alien cloud: Earth may remain unprotected for up to a million years

The heliosphere normally protects Earth from interstellar radiation. It is maintained by the solar wind, which consists of charged particles thrown by the sun. However, during the collision with the dense, icy cold interstellar cloud, the heliosphere may have been compressed so much that Earth may have been unprotected for a period of several hundred to million years.

The US research team's simulations show that the heliosphere, which shrank to a size of only 0.22 AU as the cloud passed, would have opened the door to cosmic rays and high-energy particles. The study suggests that large amounts of neutral hydrogen may have changed the chemical composition of Earth's atmosphere as a result. “This work is the first to quantitatively show that there was an encounter between the Sun and something outside the solar system that would have affected Earth's climate,” lead author Ofer says of the results.

Evidence of this theory can also be found on Earth. The study, published in June 2024, said the models are consistent with increases in radioactive iron and plutonium isotopes in the ocean, ice and snow at the South Pole and the Moon during the same period. These elements, which are often the remnants of massive stellar explosions, would have reached Earth relatively unimpeded due to the lack of a “protective bubble.”

Did solar system encounters affect evolution?

However, researchers have been unable to determine the exact effects of such a collision on Earth. “It's impossible,” says one of them. Blog post University for study to determine the exact effects. However, it is possible that this encounter could also have an impact on evolution on Earth: “Our results open a new window on the question of the relationship between the evolution of life on Earth and our cosmic neighborhood,” says Abraham Loeb, a cosmobiologist. Contributing authors.

In future work, the research team plans to look up to seven million years and even further into the history of the universe to determine the possibilities of other cosmic encounters. Another study says that about 13 million years ago, Earth may have been hit by a mysterious galactic wave. The current results are “just the beginning,” Over says.

Not only are giant clouds approaching the solar system, but interstellar meteorites, which some believe are alien spacecraft, are also likely. (g)