Galactic Cosmic Rays -- coming from outside the solar system
GCRs are atomic nuclei from which all of the surrounding electrons have been
stripped away during their high-speed passage through the galaxy. They have
probably been accelerated within the last few million years, and have
traveled many times across the galaxy, trapped by the galactic magnetic field.
GCRs have been accelerated to nearly the speed of light, probably by supernova
remnants. As they travel through the very thin gas of interstellar space,
some of the GCRs interact and emit gamma rays, which is how we know that they
pass through the Milky Way and other galaxies.
The elemental makeup of GCRs has been studied in detail , and is very similar
to the composition of the Earth and solar system. but studies of the
composition of the isotopes in GCRs may indicate the that the seed population
for GCRs is neither the interstellar gas nor the shards of giant stars that
went supernova. This is an area of current study.
Anomalous Cosmic Rays -- coming from the interstellar space at the edge of the heliopause
While interstellar plasma is kept outside the heliosphere by an interplanetary
magnetic field, the interstellar neutral gas flows through the solar system
like an interstellar wind, at a speed of 25 km/sec. When closer to the Sun,
these atoms undergo the loss of one electron in photo-ionization or by charge
exchange. Photo-ionization is when an electron is knocked off by a solar
ultra-violet photon, and charge exchange involves giving up an electron to an
ionized solar wind atom. Once these particles are charged, the Sun's magnetic
field picks them up and carries them outward to the solar wind termination
shock. They are called pickup ions during this part of their trip.
The ions repeatedly collide with the termination shock, gaining energy in the
process. This continues until they escape from the shock and diffuse toward the
inner heliosphere. Those that are accelerated are then known as anomalous
cosmic rays.
Solar Energetic Particles -- associated with solar flares and other energetic solar events
Solar energetic particles (SEPs) are atoms that are associated with solar
flares. SEPs are a type of cosmic ray. They move away from the Sun due to
plasma heating, acceleration, and numerous other forces. Flares frequently
inject large amounts of energetic nuclei into space, and the composition
varies from flare to flare. The mechanisms involved in producing a solar flare
can be better understood by studying the composition and charge of these
particles. On the scale of cosmic radiation, SEPs have relatively low energies.
Cosmic Bakcground Radiation -- 2.78K
For more information about cosmic radiation, please take a look at this
document: Cosmic Rays