The Pleistocene Epoch – with its glaciers, woolly mammoths and Neanderthals – still looms large in Earth’s rearview mirror, having ended just 12,000 years ago. Now a team of researchers proposes that those hundreds of thousands of years of our planet’s history may have been cold due to a cloud in space that briefly removed Earth from the safety of the sun’s warm glow.
The researchers hypothesize that about two million years ago, an interstellar cloud disrupted the solar system in such a way that the Earth and other planets were briefly outside the solar radiation. heliosphere, our host star’s bubble of charged particles that today forms an amorphous envelope around the system. Their research was published today in Natural Astronomy.
“This paper is the first to quantitatively demonstrate that an encounter occurred between the Sun and something outside the solar system that could have influenced Earth’s climate,” said Merav Opher, an astrophysicist at Boston University and lead author of the study, in a e-mail. to Gizmodo. Opher added that the team is “still trying to quantify this with modern climate models,” but with an increase in hydrogen and dust “the Earth would have entered an ice age.”
Opher’s team modeled data from the HI4PI research and found that our solar system may have passed through the local ribbon of cold clouds in the constellation Lynx between 2 million and 3 million years ago. The Pleistocene began about 2.6 million years ago. It is not possible to say for certain whether such cold clouds could have caused an ice age, the release said, but more evidence that clouds are tampering with the heliosphere could clarify the nature of the impact this would have on Earth.
The team’s model revealed that such a passage would shrink the heliosphere surrounding Earth and its neighboring planets to about 0.22 astronomical units, or less than a quarter of Earth’s distance from the Sun. To put that into perspective, ESA estimates that the nearest boundary of the heliosphere today is about 100 AU from the Sun, about twice as far as the Kuiper Belt.
Outside the heliosphere, Earth would have been exposed to iron and plutonium in the interstellar medium, the team suggested. Their timeline corresponds to an increase in the abundance of plutonium-244 and iron-60, two isotopes of the respective elements known to occur from events in space, in Antarctic snow, deep-sea sediments and samples from the moon. And as Opher added, samples from Mars, if tested in the same way as samples on the moon and Earth, could reveal a similar spike in the iron isotope about 2 to 3 million years ago.
The heliosphere could have been blocked for periods ranging from just a few hundred years to a million years, said Opher at Boston University. Edition. When the Earth and the other planets moved away from the cloud, the heliosphere returned.
To investigate their results, the team is now trying to pinpoint the position of the Sun around seven million years ago, where there is evidence for a new peak in the proportions of plutonium-244 and iron-60 in Earth’s ice and sediments. They are trying to create a digital twin – essentially a high-tech model – of the heliosphere to better model the conditions our solar system may have been subject to. Finally, additional data from ESA’s Gaia mission could further help the team determine the Sun’s exact position at that time in the distant past.
At least according to the Utah Geological Survey Five major ice ages have occurred on Earth. The first occurred more than 2 billion years ago and the most recent began about 3 million years ago. According to NASA, ice ages can begin due to a combination of factors, including changes in Earth’s orbit, low amounts of energy from the sun, the composition of the atmosphere, changes in ocean currents and even volcanoes, which were responsible for the ice ages. year without summer. In other words, we are not lacking in theories to explain Earth’s various cold snaps, and the jury is still out on how Earth’s being outside the heliosphere could have catalyzed such a frigid spell.
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