Radcliffe’s wave visualization, a series of dust and gas clouds (marked here) throughout the Milky Way. Approximately 400 light years from the sun, marked yellow
Alyssa A. Goodman/Harvard University
Our solar system passed through vast waves of gas and dust about 14 million years ago, darkening the views of the Earth’s night sky. The waves may have left a trace on our planet’s geological records.
Astronomers previously discovered large ocean-like waves of milky stars, gas and dust that ripple up and down for millions of years. One of these closest and most studied is the Radcliffe waves, about 9,000 light years wide and only 400 light years from the solar system.
Now, Efrem Maconi The University of Vienna and his colleagues discovered that the waves of Radcliffe once were far closer to us, surpassing the solar system 11 to 18 million years ago.
Maconi and his team used data from Gaia Space Telescope, which tracked billions of stars in the Milky Way, to identify recently formed groups of stars within the Radcliffe Wave, and identify the dust and gas clouds that formed from them.
Using these stars, they tracked the cloud orbits in time to reveal historic locations to show how the entire wave was moving. They also calculated the past paths of the solar system, rewind the clock for 30 million years, and discovered that the waves and our sun were approaching intimately about 15-12 million years ago. It is difficult to accurately estimate when the intersection began and ended, but the team believes the solar system is within the wave range around 14 million years ago.
This would have made Earth’s galactic environment as dark as it is today, as we currently live in a relatively empty space realm. “If we are in a dense region of interstellar media, that means that the light coming from the stars will dim,” says Macconi. “It’s like being on a foggy day.”
The encounter may have left evidence in Earth’s geological records and deposited radioactive isotopes on the crust, but considering how long ago it happened, this would be difficult to measure, he says. It says it is useful to find such a galactic encounter, as explaining the geological record of the Earth is a continuous problem. Ralph Schoenrich University College London.
More speculatively, the crossing appears to have occurred during a period of cooling, known as the mid-Miocene. Maconi said the two could be linked, but this would be difficult to prove. Schoenrich thinks that is unlikely. “The rule of thumb is that geology outweighs the influence of the universe,” he says. “When you move around the continent or disrupt ocean currents, you need more because climate change is occurring.”
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Source: www.newscientist.com
