Thursday, 27 November 2014

Van Allen invisible shield protects Earth from `killer electrons`..........

Washington, Nov 27: A new research has found that the two donuts of seething radiation that surround Earth, called the Van Allen radiation belts, protects Earth from the fastest and most energetic electrons.
The discovery of the drain that acts as a barrier within the belts was made using NASA's Van Allen Probes, launched in August 2012 to study the region.
First author Dan Baker from the University of Colorado said that this barrier for the ultra-fast electrons is a remarkable feature of the belts and they are able to study it for the first time, because they never had such accurate measurements of these high-energy electrons before.
Understanding what gives the radiation belts their shape and what can affect the way they swell or shrink helps scientists predict the onset of those changes and such predictions can help scientists protect satellites in the area from the radiation.
The Van Allen Probes data show that the inner edge of the outer belt is, in fact, highly pronounced and for the fastest, highest-energy electrons, this edge is a sharp boundary that, under normal circumstances, the electrons simply cannot penetrate.
The radiation belts are not the only particle structures surrounding Earth as a giant cloud of relatively cool, charged particles called the plasmasphere fills the outermost region of Earth's atmosphere, beginning at about 600 miles up and extending partially into the outer Van Allenbelt.
The particles at the outer boundary of the plasmasphere cause particles in the outer radiation belt to scatter, removing them from the belt.