What are the two competing theories that THEMIS is investigating?
Magnetospheric substorms occur in the Earth’s magnetic “tail”, which extends behind Earth, along its shadow, and extends beyond the moon, deep into interplanetary space. There are two main theories proposed to explain the trigger (onset) of magnetospheric substorms in the magnetotail: The Current Disruption theory, and the Magnetic Reconnection theory. The two competing theories can be distinguished by accurate timing. Timing determines the trigger mechanism and how it sets the entire magnetosphere into motion. The time history of these events and their macro-scale interactions, during substorms is the primary goal of the THEMIS mission. The first theory suggests that Current Disruption, which occurs around 50,000 miles (80,000km) in altitude above the equator and is due to electromagnetic turbulence that disrupts the flow of intense space currents, is the substorm trigger mechanism. The Current Disruption theory states that the cascade of events that constitutes a substorm starts clos
