Spacequakes in Earth’s Magnetic Field
Today, researchers coined a new word – spacequake! A spacequake occurs in Earth’s magnetic field and plays a key role in jolting the Northern Lights into brilliant activity.
Researchers using data from Nasa’s THEMIS spacecraft have discovered a new form of space weather. A spacequake is a reverberation of Earth’s magnetic field that would be felt most strongly in Earth orbit, but according to Vassilis Angelopoulos of UCLA, the principle investigator on the project, they could even be detected by ground stations! Evgeny Panov of the Space Research Institute in Austria says that “the total amount of energy in a spacequake can rival that of a magnitude 5 or 6 earthquake”.
The spacequake effect is caused by the collapse of Earth’s magnetic tail. The solar wind forces Earth’s magnetic field into an elongated shape stretching out far beyond our planet. Sometimes, it is stretched too far and snaps back into place like a rubber band. This snapping motion causes plasma jets to erupt which start the spacequakes.
By analyzing the data from THEMIS, researchers were able to determine that the plasma jets slammed into the geomagnetic field at about 30,000 km above the Earth. The impact sets off a rebounding process in which the the incoming plasma actually bounces up and down on the reverberating magnetic field. The bouncing starts out very strong but looses energy and the reverberations decrease. What’s interesting about this is that the plasma jets create plasma vortices which rotate at high speeds creating substantial electrical fields in the magnetosphere.
It is this intricate and complicated dance of high energy particles that can ultimately create the beautiful Aurora Borealis that we are fortunate to see here in the northern latitudes in North America!