The Battle of Magnetic Fields: Observations at Cosmic Ray Laboratory (Ooty, India)

On a fine morning in June 2015, a team of scientists at Cosmic Ray Laboratory (CRL), Ooty, went ecstatic, as they observed a burst of Galactic Cosmic Rays following a Coronal Mass Ejection event. I could only imagine the upbeat mood of the scientists at the CRL facility when they ran through these observations! After a detailed analysis of these events, they made a major announcement in a paper titled ‘Transient Weakening of Earth’s Magnetic Field Probed by a Cosmic Ray Burst’. And in layman terms that would mean ‘A Crack in Earth’s Magnetic Field’. As a science enthusiast, I was thrilled, and even more so because, the news came from my neighbouring city – Ooty in India. You have already come across quite a few new words mentioned in the above paragraphs and your curious minds would tempt you with some of the following questions:

  • What are Cosmic Rays?
  • Earth has a Magnetic Field!?
  • Coronal Mass Ejections, what are they?
  • Of what significance is this discovery to me anyway?

Let’s make sense of them now.


Galactic cosmic rays

Cosmic Rays are high-energy particles (mostly protons and nuclei of heavier atoms), whose origins are not from within our solar system, but from within our Milkyway galaxy or from outside of it. Hence the name ‘Galactic Cosmic Rays’! These charged particles get such high energies from some of the most violent events in the universe – like from a quasar, a supernova, etc. The cosmic rays can collide (interact) with matter (air molecules) in the atmosphere and produce a shower of secondary particles. ‘Muon’ is one such particle. We are most familiar with particles such as protons, electrons and neutrons, but behold – We have an entire zoo of particles!

As more ‘high energy’ cosmic rays interact with the atmosphere, more the number of muons are produced! A muon telescope can detect muons, much like how your binoculars or an optical telescope or a radio telescope can detect photons. ‘GRAPES 3 Tracking Muon Telescope‘ at CRL Ooty, is the largest and one of the most sensitive ones in the world.

Earth’s magnetic field

One competitive edge in sustaining life, that Earth has, but poor Mars doesn’t – is A Magnetic Field. The charged particles from cosmic rays and our Sun, slowly, over hundreds of millions of years, stripped the Mars of its atmosphere because it couldn’t protect itself as it lacked a magnetic shield. But good for Earth, our atmosphere isn’t going anywhere! We have a protector! Earth has its own magnetic field (one can imagine Earth to behave like a really big bar magnet).

As most of us would have definitely tried in our childhood days, Iron filings, when sprinkled on a sheet of paper placed on a bar magnet, would align themselves to form a pattern. The pattern in which they align would represent the magnetic field and its strength around the magnet. Earth can also be imagined as a magnet having a similar pattern of the magnetic field around it (but in 3 dimensions). This is our shield! Our watchful protector! But no matter how protected we are, some particles will have sufficient energy to break in.

The battle of fields

On 22nd June 2015, ‘GRAPES-3 tracking muon telescope’ detected a sharp increase in the number of muons, lasting for almost 2 hours. Only 40 hours prior to this, 150 million km away from our Earth, huge amounts of plasma (charged particles) were ejected from the Sun and began their journey towards us – A Coronal Mass Ejection event. It is known that the plasma themselves carry a magnetic field as they travel.

When the magnetic fields of the plasma reach and interact, they reshape the magnetic field patterns around the Earth. Such events are called geomagnetic storms. This is like disturbing the magnetic field pattern of a bar magnet by bringing in another bar magnet with opposite orientation near it. These events can weaken the magnetic field of Earth for a brief period of time-based on the orientation and strength of the interacting field. This weakened field is now like an open invitation, not only for more number of ‘high energy’ cosmic rays but also for ‘lower energy’ cosmic rays that were previously shielded by our magnetic field. This is an epic battle going on endlessly, where the cosmic rays are constantly trying to breach, but our defence is strong enough to shield. These cosmic rays, however, occasionally, are flanked by an entire army of charged particles from the Sun (Coronal mass ejection), which can weaken our defence system, and cosmic rays are able to breach and harm. But as this battle begins to fade away, our magnetic field regains its strength.

The mesmerising northern and southern lights, which you can enjoy seeing from latitudes closer to the poles, are visual spectacles across the night sky driven by the epic battle of the magnetic fields! Studying cosmic rays can help us in understanding the nature of geomagnetic storms, the consequences they can have on Earth, and be better prepared to handle more severe storms.

Such events can potentially damage our satellites, cripple our communication systems and in most severe cases can short-circuit high voltage transformers, thus permanently destroying the electrical grid, and thereby depriving humanity of electrical power on Earth. Today can we imagine life without electricity? After the news of this breakthrough discovery was in the air, it was not only the discovery but the legend of Cosmic Ray Laboratory itself that started to spread like wildfire across the world.

Right from the inspiring work culture and ethics, to building the state of the art equipment, to organising winter schools to share the knowledge and wisdom to the students and much more – Cosmic Ray Laboratory – I would say is an epitome of an amazing research facility.

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