Indian scientists detect crack in Earth's magnetic shield

Telescope in TN records galactic cosmic ray bursts of 20 GeV lasting 2 hours in 2015.

The world’s largest and most sensitive cosmic ray monitor, located in India, has recorded a burst of galactic cosmic rays that indicates a crack in Earth's magnetic shield. The burst occurred when a giant cloud of plasma ejected from the solar corona struck Earth at very high speeds causing massive compression of Earth's magnetosphere and triggering severe geomagnetic storm. The GRAPES-3 muon telescope located at Tata Institute of Fundamental Research's Cosmic Ray Laboratory in Ooty, Tamil Nadu, recorded the cosmic rays of about 20 GeV last year lasting for 2 hours. The burst occurred when a giant cloud of plasma ejected from the solar corona, and moving with a speed of about 2.5 million kmph struck Earth, causing severe compression of its magnetosphere from 11 to 4 times the radius of Earth. It triggered a severe geomagnetic storm that generated aurora borealis and radio signal blackouts in many high latitude countries, according to the study published in the journal Physical Review Letters. Earth's magnetosphere extends over a radius of a million km, which acts as the first line of defence, shielding us from continuous flow of solar and galactic cosmic rays, thus protecting life on Earth from high intensity energetic radiations. Numerical simulations performed by the GRAPES-3 researchers, including Pravata K Mohanty, indicate that Earth's magnetic shield temporarily cracked due to the magnetic reconnection, allowing the lower energy galactic cosmic ray particles to enter our atmosphere. Earth's magnetic field bent these particles about 180-degrees, from the day-side to the night-side of the Earth where it was detected as a burst by the GRAPES-3 muon telescope around mid-night on 22 June 2015. The data was analysed and interpreted through extensive simulation over several weeks by using the 1280-core computing farm that was built in-house by the GRAPES-3 team.