Analysis of a cosmic event from Jun. 2015 revealed Earth's magnetic shield cracked, allowing cosmic rays to leak into the atmosphere and causing geomagnetic storms in the Northern Hemisphere.
The GRAPES-3 muon telescope in Ooty, India, detected a spike in cosmic ray levels in Jun. 2015, but the severity of the event wasn’t revealed until Nov. 2016 through a study published in the scientific journal Physical Review Letters.
The study reports for two hours on Jun. 22, 2015, particles from a giant cloud of fast-moving plasma penetrated the Earth’s atmosphere at approximately 1.6 million mph. The particles, originating from the surface of the sun, caused the Earth’s magnetosphere to shrink from 11 times to 4 times the earth’s radius -- allowing harmful solar winds to breach the Earth’s surface.
Earth’s magnetosphere acts as the first line of defense between the Earth and the flow of galactic cosmic rays, which shield life on the planet from harmful ultraviolet radiation. It has a radius of over 620,000 miles, according to Wired.
Numerical simulations of the event performed by the GRAPES-3 collaboration propose that the Earth’s magnetic shield cracked due to magnetic reconnection, allowing low-energy galactic cosmic ray particles to enter the atmosphere.
"This vulnerability can occur when magnetized plasma from the Sun deforms Earth’s magnetic field, stretching its shape at the poles and diminishing its ability to deflect charged particles," Katherine Wright explains on the American Physical Society's website.
The solar wind triggered a severe geomagnetic storm at the time of the event, generating vivid aurora borealis -- also known as "northern lights" -- and radio signal blackouts in many high-altitude countries.
The study reports the surge in cosmic activity indicates “transient weakening of Earth’s magnetic shield.”
The study authors remain optimistic for Earth geomagnetic future, saying the research may “hold clues for a better understanding of future superstorms that could cripple modern technological infrastructure on Earth.”