Earth’s journey through the galaxy may have had a profound impact on our planet’s geology. New research suggests that every 200 million years, Earth is bombarded by high-energy comets as it passes through the spiral arms of its galaxy, a bombardment that could thicken Earth’s continental crust.
The team behind the new findings believe that the dense cloud of gas in the spiral arms is related to comet on the edge solar systemlet them fly to Earth.
“As geologists, we generally think that the processes inside the Earth are very important to how our planet evolves,” Chris Kirkland, a geologist at Curtin University in Australia and lead author of the study, said in an article. statement (opens in new tab)“But we can also think on a larger scale, looking at extraterrestrial processes and where we are in the galactic environment.”
related: Earth’s oldest crystal reveals age of plate tectonics
The team reached their conclusions by examining zircon crystals from two of the oldest continents and regions on Earth that preserve Earth’s earliest continental history: the North American Craton in Greenland and the Pilbara in Western Australia Pull through.
The decay of uranium in zircon crystals in these regions has been used to create a geological timeline spanning 1 billion years, from 2.8 billion to 3.8 billion years ago, during the Archean.This timeline could help geologists discover how Earth Be the only planet known to have continents and active plate tectonics.
Isotopes of the element hafnium in zircon allow scientists to spot periods in Earth’s history that experienced influx of juvenile magma — magma containing elements that had never reached the surface before — signs that the Earth’s crust was created.
Kirkland and his team found that over long periods of time, the crust produced patterns that correspond to galactic years. (A galactic year is the time it takes the sun to orbit the center of the Earth once Milky Way.) These findings were further supported by oxygen isotope examinations showing a similar pattern.
The team therefore concluded that Earth’s journey around the galactic center helped shape Earth’s geology.
Earth’s Journey Around the Galactic Center
Not only does the solar system orbit around the galactic center, but the spiral arms radiating from it also rotate, albeit at different speeds.
The sun orbits the center of the galaxy at about 536,000 mph (863,000 km/h), while the spiral arms rotate at about 47,000 mph (76,000 km/h). That means the sun and the solar system, along with many other stars in the Milky Way, move in and out of the spiral arms, like fans do “waves” in a stadium.
As the solar system moves into the spiral arm, Oort Cloud on its outer edge (about 4.6 trillion miles, or 7.4 trillion kilometers, sun) interacts with the dense gas cloud in the whip arm, sending icy material toward the inner solar system—and our planet.
The energy ratio of these objects upon arrival asteroid Hit the earth regularly.Most of these space rocks come from the main asteroid belt in between Mars and Jupitera region closer to Earth than the Oort Cloud.
“This is important because more energy leads to more melting,” Kirkland said in the statement. “When it hits, it causes a lot of decompressed melting, which creates a larger bulge of material.”
The impact’s impact on rock formation and increased crustal formation was also evident in the team’s examination of pebble beds, deposits of small spheres created by ejected material that cool, condense and fall back to Earth after impact. The spheroid bed is also associated with Earth’s entry into the Milky Way’s dense spiral arms about 3.3 billion to 3.5 billion years ago, when Earth was just over a billion years old.
Determining the age of more sediments in the spheroid bed could further support the team’s findings, which in turn encourages geologists and astrophysicists to start thinking more about how Earth’s wider cosmic environment affects Earth’s geology.
“It’s hard to prove these things; we want to make that connection and start a conversation to study geological processes beyond Earth, beyond the solar system, and what might drive those processes,” said Phil Sutton, a lecturer and co-author of the study. Phil Sutton, PhD in astrophysics at the University of Lincoln, UK, said “We didn’t just form in isolation.”
The team’s findings were published online Aug. 23 in the journal geology.
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