  In a field overflowing with beautiful images of the Sun, solar energetic
particle (SEP) events are a hidden asset, perhaps a secret weapon, that can
sample the solar corona and carry away unique imprints of its most bizarre and
violent physics. Only recently have we found that the abundances of the
elements in SEPs carry a wealth of data, not only on their own acceleration and
history, but on plasma temperatures at their source, and on aspects of the
genesis of the corona itself. SEPs are the tangible product of differing
energetic outbursts at the Sun. They come in extremes. Little "impulsive" SEP
events from magnetic reconnection in solar jets (also in flares), have most
unusual 1000-fold resonant enhancements of 3He and of heavy elements like Au or
Pb, while large "gradual" SEP events accelerated at shock waves driven by
coronal mass ejections (CMEs), sample the composition of the corona itself, but
also accelerate GeV protons that threaten Mars-bound astronauts with hazardous
radiation. Direct SEP measurements plus solar images provide complimentary,
"multi-messenger" data on high-energy physics at the Sun.
