A Third Belt Around Earth
In August 2012, NASA launched two Radiation Belt Storm (RBS) probes to study our Earth's magnetic field. They were particularly interested in understanding the Van Allen Belts -- two rings of charged particles surrounding our Earth.
But the unexpected happened. When the probe's detectors were turned on, it detected a third ring encircling our Earth. How could that be? Since confirmed by the Explorer missions in 1958, it was believed that our Earth was only surrounded by two rings.
The finding gets even more interesting -- after four weeks, the probes detected only two rings. The third ring had disappeared as mysteriously as it had appeared!
What are Van Allen Belts?
Lets take a step back to understand how Van Allen belts form. As you know, the interior of our Earth is made of swirling hot magma. This gives our planet a magnetic field, with the field lines running from the South pole to the North pole. Trapped in this magnetic field are charged particles that are spewed out by our Sun and from cosmic rays originating in outer space.
Our Earth pulls these trapped particles along its field lines, just as a magnet would pull iron filings. The charged particles form two belts -- known as Van Allen belts. The outer belt is made up of high energy electrons, while the inner one is mainly made up of electrons and protons.
The Mysterious Third Belt
As it turns out, just before the probes were turned on, our Sun spewed out a massive stream of charged particles in what is known as a solar storm (we had written here). The storm tore apart the outer Van Allen belt, and re-arranged the particles into two outer rings. Within four weeks, another intergalactic storm, more energetic than the previous one, restored the two-ring structure.
According to Daniel Baker, a space physicist at University of Colorado, Boulder -- "the findings demonstrate that solar outbursts are indeed a strong driving force behind the structure of the belts." Scientists will be using this observation to create better models of the radiation belts and its impact on space weather, spacecrafts and communication satellites.
Courtesy NASA, CSMonitor