Van Allen Radiation Belts: Less Mysterious But Just As Deadly
The mysterious and deadly Van Allen radiation belts surrounding the earth are a little less mysterious today (but just as deadly)
The Van Allen radiation belts are torus (or doughnut) shaped regions of space consisting of energetic charged particles. Two primary regions have been identified, an outer belt and an inner belt. The former is composed of electrons while the inner has pesky protons as well. These particles come from the sun’s solar wind and cosmic rays and remain in these regions because they are trapped by the earth’s magnetic field called the magnetosphere. Yes, I’ll say it… “IT’S A TRAP”
Skeptic Aside: This radiation is quite deadly and thus is one of the many examples used by conspiricists to support the absurd belief that we never went to the moon…dead astronauts don’t leave footprints you know. We’ve known about these belts for quite some time though and the astronaut’s exposure to this region was sufficiently brief (they went through the thinnest part) to ensure a life free of belt-induced cancer
The outer Van Allen belt is different from its partner though in that it often changes its size and composition and is composed of relativistic electrons. How they attain velocities near the speed of light has been a long-standing mystery that may now be resolved by twin Van Allen probes that have been hanging out in the belts for a while.
It looks like the immense electron speeds are a by-product of a one-two punch that kicks them into overdrive. This process begins with a relatively gentle push by quick pulses in the electric field that runs parallel to earth’s magnetic field. The push isn’t tremendous but it’s enough to synchronize the electrons with something I’ve never heard before called Whistlers. These are giant low frequency electromagnetic waves generated by lightning that propagate along the magnetic field lines of earth into space. This synchronization allows the Whistlers to grab hold of the electrons and accelerate them to deadly speeds that would make any super-villain proud.
This stuff isn’t just of academic interest. This process is important; knowledge of it can help safeguard not only sensitive electronics but also astronauts. It could also help elucidate similar events on the sun and other planets with a magnetic field.
The next time you see lightning (and it doesn’t hit you), be glad you’re not in space being pelted with relativistic electrons
Image Credit: NASA