New research from Boston University and the Harvard Radcliffe Institute suggests that the Sun passed through a large hydrogen cloud two million years ago, directly impacting its protective heliosphere and may have forever changed all life on Earth. The evidence for this event and its effects on Earth’s climate also indicates that the location of the Sun in the galaxy may have a direct effect on the plants and animals that live on Earth.
“This paper is the first to show quantitatively that there was an encounter between the sun and something outside the solar system that would have affected Earth’s climate,” said astrophysicist Merav Opher, a professor of astronomy at Boston University and a collaborator on Harvard Radcliffe Institute in press release announcing the team’s study.
Although climate change is currently a politically charged topic, the plants and animals living on Earth have experienced repeated and dramatic fluctuations in their environment for millions of years. Historically, events such as volcanic eruptions, shifting plate tectonics, changes in atmospheric carbon dioxide levels, and even the Earth’s tilt and rotation have likely contributed to these extreme climatological changes.
As an astrophysicist specializing in the study of the Sun’s heliosphere, which is a stellar wind halo of highly charged particles that encloses and shields the rest of the Solar System from harmful interstellar radiation and galactic rays, Opher speculated that if the Sun would come into contact with one of the giant hydrogen bubbles floating around our galaxy, it could also have a direct and dramatic effect on the planet’s climate. Now, she believes her team’s study supports that theory. Adding yet another factor to the ever-evolving picture of Earth’s climate.
“Stars move,” Opher said, “and now this paper is showing not only that they move, but that they undergo drastic changes.”
Astrophysics ‘Time Travel’ Reveals Sun’s Position Two Million Years Ago
To test the team’s theory, Opher, whose previous work suggesting that the heliosphere is shaped like a puffy croissant supposedly “shocked the space physics community,” decided to use computer models to track the Sun’s movement through the galaxy. Turning the dial of the astronomical clock back in time, Opher came across an event that took place about two million years ago.
In their study published in the journal Astronomy of Nature, Opher and colleagues explain how a string of large, dense interstellar clouds of extremely cold hydrogen atoms called the Local Ribbon of Cold Clouds system was rather precariously positioned. On closer inspection, the simulators’ “astrophysical return machine” showed that one of the clouds, the Local Cold Cloud Lynx, may have collided with the heliosphere due to its position near the end of a distinct band of the Local Cold Belt. . clouds.
According to Opher, if such an impact were to occur, the team’s simulations show that it could have altered the heliosphere enough to temporarily deprive Earth of its critical shields. This means that all life on Earth would not only be inundated with extremely powerful levels of interstellar radiation and cosmic rays (which can alter DNA), but would also have been exposed to dangerous amounts of iron and plutonium atoms left over from exploding stars that exist measurably. concentrations within the interstellar medium.
“This cloud was really in our past, and if we passed something that massive, we were exposed to the interstellar medium,” says Opher.
In support of this idea is geological evidence showing extremely high concentrations of the isotopes 60Fe (iron 60) and 244Pu (plutonium 244) in the ocean, on the Moon, buried in Antarctic snow, and collected from ice cores from the same period. time two million years ago. . While no direct research has been done to determine what the collective effects of a prolonged removal of heliospheric shielding and all of this exposure might be, the authors of the paper describing this possibility believe that it may have had a direct effect. in everything that lives on Earth.
“Only rarely does our cosmic neighborhood beyond the solar system affect life on Earth,” says Avi Loeb, director of Harvard University’s Institute for Theory and Computation and co-author on the paper. “It is exciting to discover that our passage through dense clouds a few million years ago may have exposed Earth to a much greater influx of cosmic rays and hydrogen atoms.” Loeb is also a regular contributor to Debrief.
Next steps and other possible cosmic collisions
While there is no direct way to travel back in time to see how the Sun’s collision with an interstellar cloud of cold hydrogen atoms might have affected our ancient human ancestors or the plants and animals living near them, a theory suggests that a large enough event may have triggered one of the many ice ages that Earth has experienced during its lifetime. In fact, given the more than four billion years since our Solar System was formed, Opher believes it’s likely that the Sun has experienced many similar events in the past, all of which could have affected life in a number of different and unpredictable ways.
“And it’s likely to encounter more in a million years or so,” explains the press release announcing the study.
Next, Opher and her team at the university’s NASA-funded DRIVE (Solar Wind with Hydrogen Ion Exchange and Large-scale Dynamics) DRIVE Science Center will begin to explore how such a massive collision might have affected the the sun and an interstellar cloud of hydrogen atoms. Earth’s atmosphere and climate, but also its radiation.
After that, the researchers plan to trace the sun’s position seven million years ago. If their assumptions are correct, data collected by the European Space Agency’s Gaia mission, which is building the largest ever three-dimensional map of the galaxy and also tracks how fast stars move, should not only help them determine the location of the Sun within the galaxy, but also determine where the cold cloud system bands were. If the two coincide with any known climate events in Earth’s past, it could add even more evidence to the team’s theory.
“This is just the beginning,” says Opher.
Moving forward, the astrophysicist says she hopes this paper will open the door to a greater exploration of how the solar system was affected by external forces in the deep past, and how those forces, in turn, have shaped life on Earth. our planet. Loeb agrees.
“Our results open a new window on the relationship between the evolution of life on Earth and our cosmic neighborhood,” he said.
Christopher Plain is a science fiction and fantasy novelist and chief science writer at The Debrief. Follow and connect with him X, learn about his books at plainfiction.com or email directly at christopher@thedebrief.org.