Recent research reveals that our solar system traversed a significant wave of gas and dust approximately 14 million years ago, resulting in a darker night sky for Earth. This wave could also hold clues in our planet’s geological history.
Astronomers have previously identified large, ocean-like waves comprising stars, gas, and dust in the Milky Way that oscillate over millions of years. One of the closest and most extensively studied of these formations is the Radcliffe Wave, which spans nearly 9,000 light-years and is located about 400 light-years from our solar system.
Efrem Maconi and his team at the University of Vienna have now determined that the Radcliffe Wave once passed much closer to our solar system, likely between 11 and 18 million years ago.
Utilizing data from the Gaia space telescope, which has cataloged billions of stars within the Milky Way, the researchers identified recently formed star clusters within the Radcliffe Wave, alongside the gas and dust clouds from which they originated. By tracing the movements of these stars, they retroactively tracked the orbits of these clouds to discern their historical positions, revealing that our sun and the wave were in close proximity approximately 14 million years ago.
This encounter would have rendered Earth’s galactic surroundings considerably dimmer, as we currently exist in a relatively sparse region of space. “Being in a denser section of the interstellar medium would dim the light coming from the stars,” explains Maconi. “It’s akin to experiencing a foggy day.”
The interaction may have also left its mark in Earth’s geological layers, potentially depositing radioactive isotopes in the crust. However, the age of this event complicates any measurements, according to the researchers. Understanding Earth’s geological history is an ongoing challenge, making the identification of such cosmic encounters valuable, notes a contributor from University College London.
Interestingly, this wave crossing coincided with a cooling period on Earth known as the Middle Miocene. Although the connection is speculative, it opens avenues for further investigation, even if some experts remain skeptical about a direct relationship, emphasizing that geological processes often have a more pronounced impact on climate shifts.
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