[SFDXA] unexpected interplanetary shock

[Bill Marx]

Space Weather News for May 11, 2002

An unexpected interplanetary shock wave swept past Earth at 1000 UT on May
11th and triggered a moderate geomagnetic storm. High-latitude sky
watchers -- i.e., those in northern Europe, Canada and across the northern
tier of US states -- should be alert for auroras after local nightfall on
Saturday.  Although the shock wave was not a particularly strong one, it
stimulated a geomagnetic storm because the interplanetary magnetic field
near Earth is pointing south -- a condition that weakens our planet's
magnetic defenses against solar wind disturbances.  Visit spaceweather.com
for updates.