RADIATION
STORM: A low-level radiation storm
is underway
as solar protons swarm around our planet. Ranked
S1 on NOAA space weather scales, the storm poses
no serious threat to astronauts or satellites. Nevertheless
it is a nuisance. Minor radiation storms can cause
occasional reboots of computers onboard spacecraft
and add "snow" to spacecraft imaging systems.
This SOHO coronagraph
image of the sun, taken during the early hours of
July 20th, is a good example:
Each of the speckles in the image
(a handful are circled) are caused by protons hitting
the spacecraft's CCD camera. During minor storms
it is possible to see through this kind of snow.
During severe storms, such images become practically
opaque.
The protons were accelerated toward
Earth by an M7-class solar flare on July 19th. Although
the blast site (sunspot AR1520) was on the farside
of the sun, the protons were able to reach Earth
anyway, guided toward our planet by backward-spiralling
lines of magnetic force.
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