Scientists have detected a crack in the earth's magnetic shield, raising fears about the potentially destructive effect of future solar superstorms.
The crack was discovered during research into a huge cosmic ray storm in June 2015, which saw the earth's magnetosphere - or shield - bombarded with cosmic particles of high radiation for two full hours.
Cosmic rays are very powerful and can easily blast through the hull of a spacecraft. The earth's magnetic shield is our first line of defence against them.
Forty hours before the cosmic ray burst, the sun ejected a giant cloud of plasma from its outer atmosphere, striking the magnetosphere at speeds of about 2.5 million kilometres per hour.
This caused many geomagnetic storms and led to radio signal blackouts in high-latitude countries in North and South America.
Researchers have been analysing images from the GRAPES-3 muon telescope in Ooty, India since those storms. The researchers, from the Tata Institute of Fundamental Research, found the magnetosphere had been temporarily cracked, after performing simulations based on the GRAPES-3 data.
They also say the burst of rays caused severe compression of the magnetosphere, shrinking it from 11 to four times the radius of Earth.
Researchers believe the bombardment could have been powerful enough to reconfigure our magnetic shield, meaning it temporarily opened weak spots to let radiation and cosmic rays through.
The research, published in Physical Review Letters, suggests that although the magnetic field was only temporarily cracked, the fact it can be cracked at all is a huge concern.
A report on the American Physical Society Website says that: "This vulnerability can occur when magnetised plasma from the Sun deforms Earth’s magnetic field, stretching its shape at the poles and diminishing its ability to deflect charged particles.
"[This] indicates a transient weakening of Earth’s magnetic shield, and may hold clues for a better understanding of future superstorms that could cripple modern technological infrastructure on Earth, and endanger the lives of the astronauts in space."