About 14 million years ago, in the middle of the Miocene epoch, the solar system passed through the Orion Nebula. At the same time, the Earth cooled and the Antarctic ice sheet formed. Is there a connection between the two phenomena?
Millions of years ago, the solar system sailed through the Orion Nebula, part of the Radcliffe Waves structure.
This cosmic journey may have affected Earth's climate by compressing the heliosphere and increasing the amount of interstellar dust, with researchers using data from the European Space Agency's Gaia mission identifying the trajectory and linking it to the mid-Miocene climate transition – a significant change in Earth's climatic history.
The solar system on its journey through the Orion Nebula
An international team, led by researchers from the University of Vienna, has discovered that the solar system passed through the Orion Nebula, and through part of the Radcliffe Waves, about 14 million years ago. This journey through a dense region of space may have compressed the heliosphere – the protective envelope of the solar system – and increased the flow of interstellar dust. Scientists believe that this phenomenon could have affected Earth’s climate and left evidence in the geological record.
This discovery, recently published in the journal Astronomy & Astrophysics, highlights a fascinating connection between astrophysics, paleoclimate, and geology.
As the solar system orbits the center of the Milky Way, it moves through changing galactic environments – like a ship sailing through changing sea conditions, explains Ephraim Maconi, lead researcher and doctoral student at the University of Vienna. “Our sun encountered a region of high gas density as it passed through the Radcliffe waves in the Orion region.”
Using Gaia data and spectroscopic observations, the team detected the solar system passing through Radcliffe waves in the Orion region about 14 million years ago. "This discovery is a continuation of our previous work on the detection of Radcliffe waves," notes João Alves, professor of astrophysics at the University of Vienna and co-author of the study.
The region in Orion, where star clusters such as NGC 1977, NGC 1980, and NGC 1981 formed, is now visible in the northern hemisphere winter sky and the southern hemisphere summer sky. The dust that was created by the galactic encounter may have entered Earth's atmosphere and left traces of radioactive elements from the supernova explosion in the geological record.
Possible connection to climate
The study suggests that the solar system transit in the Orion region occurred between 18.2 and 11.5 million years ago, with the most likely date being between 14.8 and 12.4 million years ago – a period that corresponds with the mid-Miocene climate transition when Earth moved from a warm and variable climate to a cooler climate, with the formation of the Antarctic ice sheet. Although the discovery suggests a possible link between the galactic transit and Earth's climate via interstellar dust, the researchers emphasize that further research is needed to prove a causal link.
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