New research from Boston University and the Harvard Radcliffe Institute suggests that the Sun passed through a massive hydrogen cloud two million years ago, directly affecting its protective heliosphere and could have permanently altered all life on Earth. Evidence from this event and its effects on Earth’s climate also shows that the Sun’s position in the galaxy can have a direct effect on the plants and animals living 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, professor of astronomy. at Boston University and a member of the Harvard Radcliffe Institute at Boston University. press release announcing the team’s study.
Although climate change is currently a politically charged topic, plants and animals living on Earth have been experiencing repeated and dramatic changes in their environments for millions of years. Historically, events such as volcanic eruptions, changes in plate tectonics, changes in atmospheric carbon dioxide levels, and even the tilt and rotation of the Earth have likely all 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 surrounds and protects the rest of the solar system from harmful interstellar radiation and galactic rays, Opher issued the hypothesis that if the Sun were to come into contact with one of the large hydrogen bubbles floating around our galaxy, it could also have a direct and dramatic effect on the planet’s climate. She now believes her team’s study supports this theory. This adds yet another factor to the ever-changing picture of Earth’s climate.
“Stars move,” Opher said, “and now this paper shows not only that they move, but that they undergo drastic changes.”
Astrophysics ‘time travel’ reveals position of Sun two million years ago
To test the team’s theory, Opher, whose previous work suggesting that the heliosphere is shaped like an inflated crescent reportedly “shocked the space physics community,” decided to use computer models to track the movement of the Sun through the galaxy. By winding the face of the astronomical clock, Opher discovered an event that occurred approximately two million years ago.
In their study published in the journal Natural astronomy, Opher and his colleagues explain how a chain of large, dense interstellar clouds made of extremely cold hydrogen atoms, called the Cold Cloud Local Ribbon System, was positioned rather precariously. Checking more closely, the simulator’s “astrophysical feedback machine” showed that one of the clouds, the local Cold Cloud Lynx, might have collided with the heliosphere due to its position near the tip. of a particular ribbon of the local Cold Ribbon. Clouds.
According to Opher, if such a collision occurred, the team’s simulations indicate that it could have altered the heliosphere enough to temporarily deprive Earth of its critical protections. This means that all life on Earth would not only have been exposed to incredibly 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 behind by exploded stars that exist in measurable proportions. concentrations in the interstellar medium.
“This cloud was indeed in our past, and if we passed through something that massive, we were exposed to the interstellar medium,” Opher explains.
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 cores of ice dating from the same period two million years ago. . Although no direct research has been done to determine what the collective effects of prolonged removal of heliosphere protection and all this exposure might be, the authors of the paper highlighting this possibility believe it could have had a direct effect on everything that lives on the planet. Earth.
“Our cosmic neighborhood beyond the solar system rarely affects life on Earth,” says Avi Loeb, director of the Institute for Theory and Computation at Harvard University and co-author of the paper. “It is exciting to discover that our passage through dense clouds a few million years ago could have exposed Earth to a much greater flux of cosmic rays and hydrogen atoms.” Loeb is also a regular contributor to The debriefing.
Next steps and other potential cosmic collisions
Although 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 may have affected our ancient human ancestors or the plants and animals living alongside them, one theory suggests that a large enough event could have triggered one of the many ice ages Earth has experienced during its lifetime. In fact, given the four billion years since the creation of our solar system, Opher thinks it’s likely that the Sun has experienced many similar events in the past, all of which could have affected life in different ways and unpredictable.
“And this will probably happen more in about a million years,” says the press release announcing the study.
Next, Opher and his team at the NASA-funded DRIVE SHIELD (Solar Wind with Hydrogen Ion Exchange and Large-scale Dynamics) science center will begin to explore how such a massive collision between the sun and an interstellar cloud d Hydrogen atoms could have affected the Earth’s atmosphere and climate, but also radiation.
The researchers then plan to trace the position of the sun back to seven million years ago. If their hypotheses 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 plotting how fast stars move, should not only help them to precisely pinpoint the location of the Sun in the galaxy, but We also identified where the ribbons of the cold cloud system were located. If both coincide with known climate events in Earth’s past, it could add even more evidence to the team’s theory.
“This is just the beginning,” Opher says.
In the future, the astrophysicist hopes this paper will open the door to much deeper exploration of how the solar system was influenced by external forces in the deep past and how those forces, in turn, shaped life on 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 senior science editor at The Debrief. Follow and connect with him on X, check out his books at plainfiction.com or email him directly at christopher@thedebrief.org.