Spacequakes
Rumble Near Earth
Researchers
using NASA's fleet of five THEMIS spacecraft
have discovered a form of space weather that
packs the punch of an earthquake and plays a
key role in sparking bright Northern Lights.
They call it "the spacequake."
A spacequake
is a temblor in Earth's magnetic field. It is
felt most strongly in Earth orbit, but is not
exclusive to space. The effects can reach all
the way down to the surface of Earth itself.
"Magnetic
reverberations have been detected at ground
stations all around the globe, much like
seismic detectors measure a large
earthquake," says THEMIS principal
investigator Vassilis Angelopoulos of UCLA.
It's
an apt analogy because "the total energy
in a spacequake can rival that of a magnitude
5 or 6 earthquake," according to Evgeny
Panov of the Space Research Institute in
Austria. Panov is first author of a paper
reporting the results in the April 2010 issue
of Geophysical Research Letters (GRL).