  Dark matter capture and annihilation in planets and their satellites, in
addition to producing neutrinos (already the basis of several ongoing
experiments), is shown to lead to more significant heat generation in these
bodies for a uniform dark matter halo. This thermal output becomes more
prominent when clumped dark matter passes through the solar system. The dark
matter annihilations should be treated as a new source of heat in the solar
system which in some special cases may lead to unique imprints. Such new
signatures of the dark matter are found in the generation of the puzzling
magnetic field of Ganymede. This new source of heat perhaps cannot explain the
formation and segregation of Ganymedean structure (which are probably due to
conventional gravitational and radioactive heating), but provides a possible
explanation of the origin of the Ganymedean magnetic field.
