New research from Boston University and the Harvard Radcliffe Institute suggests that two million years ago, the Sun passed through a giant hydrogen cloud that directly affected its protective heliosphere and could have permanently altered all life on Earth. Evidence of this event and its effects on Earth’s climate also shows that the position of the Sun in the galaxy can have a direct effect on plants and animals living on Earth.
“This paper is the first to quantitatively show that there has been a collision 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 member of the Harvard Radcliffe Institute. 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 over millions of years. Historically, events such as volcanic eruptions, shifting plate tectonics, shifts in atmospheric carbon dioxide levels, and even the tilt and rotation of the Earth have likely contributed to these extreme climate shifts.
As an astrophysicist who specializes in the study of the Sun’s heliosphere, a halo of stellar wind made up of highly charged particles that surrounds and shields the rest of the Solar System from harmful interstellar radiation and galactic jets, Opher speculated that if the Sun were to come into contact with one of the large hydrogen bubbles floating around our galaxy, it can also have a direct and dramatic effect on the planet’s climate. Now she believes her team’s study supports that theory. It adds another factor to the ever-evolving picture of Earth’s climate.
“Stars are moving,” Opher said, “and this paper now shows not only that they are moving, but that they are experiencing drastic changes.”
“Time Travel” Astrophysics 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 puffed bagel reportedly “shook the space physics community,” decided to use computer models to track the Sun’s motion in the galaxy. Turning the clock face back in time, Opher stumbled upon an event that happened about two million years ago.
In his study published in the journal Astronomy of natureOpher and colleagues explain how a string of large, dense interstellar clouds composed of extremely cold hydrogen atoms, called the Local Ribbon of Cold Clouds system, was located quite precariously. Upon closer inspection, the simulator’s “astrophysics journey back machine” showed that one of the clouds, the Local Lynx of Cold Cloud, may have collided with the heliosphere due to its position near the end of one particular Local Ribbon of Cold. Clouds.
According to Opher, if such a collision were to occur, the team’s simulations suggest it could change the heliosphere enough to temporarily deprive Earth of its critical protection. This means that all life on Earth would not only be saturated with incredibly strong levels of interstellar radiation and cosmic rays (which can alter DNA), but would also be exposed to dangerous amounts of iron and plutonium atoms left over from exploded stars that exist in measurable concentrations in the interstellar medium. environment.
“This cloud was really in our past, and if we crossed something that massive, we were exposed to the interstellar medium,” says Opher.
This idea is supported by geological evidence showing unusually 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 two million years ago. . While no direct research has been done to determine what the collective effects of the widespread removal of heliosphere protection and all of this exposure might be, the authors of the paper outlining the possibility believe that it could have had a direct effect on all life on the planet. Earth.
“Our space neighborhood beyond the Solar System rarely affects life on Earth,” says Avi Loeb, director of Harvard University’s Institute for Theory and Computation and co-author of the paper. “It is exciting to find that our passage through dense clouds several million years ago may have exposed Earth to a much greater flux of cosmic rays and hydrogen atoms.” Loeb is also a regular contributor Debrief.
Next steps and other potential cosmic collisions
While there is no direct way to travel back in time to see how the collision of the Sun with an interstellar cloud of cold hydrogen atoms might have affected our ancient human ancestors or the plants and animals living next to them, one theory suggests that a large enough event could . triggered one of the many ice ages the Earth has experienced in its lifetime. In fact, given the more than four billion years since our Solar System 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 many different and unpredictable ways.
“And they’ll probably run into more in the next million years,” explains the press release announcing the study.
Next, Opher and her team at the university’s NASA-funded SHIELD (Solar Wind with Hydrogen Ion Exchange and Large-scale Dynamics) DRIVE science center will begin to investigate how such a massive collision between the Sun and an interstellar cloud of hydrogen atoms could have affected it. Earth’s atmosphere, climate, but also radiation.
After that, scientists plan to trace the Sun’s position back to seven million years ago. If their assumptions are correct, data collected by the European Space Agency’s Gaia mission, which is building the largest three-dimensional map of the galaxy to date and also tracking how fast the stars are moving, should help them not only determine the position of the Sun in the galaxy, but also determine where the bands were cold cloud system. If the two match 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.
The astrophysicist says she hopes the paper will open the door to a much larger study of how the solar system was affected by external forces in the deep past and how those forces subsequently shaped life on our planet. Loeb agrees.
“Our results open a new window into the relationship between the evolution of life on Earth and our cosmic neighborhood,” he said.
Christopher Plain is a science fiction and fantasy writer and senior science writer at The Debrief. Follow him and connect with him X, learn about his books at plainfiction.com or email him directly at christopher@thedebrief.org.