The Energetic Gamma-Ray Experiment Telescope (EGRET) instru ment on the Compton Gamma-Ray Observatory left as a legacy its Third Catalog of High Energy Gamma-Ray Sources, whose detections include a large number of blazars, some pulsars, the Large Magellanic Cloud and a solar flare. Most of the newly discovered objects - a majority of the catalog -are unidentified sources, with a clearly predominant Galactic population. Are all these radio-quiet pulsars, like Geminga, or is there a novel type of celestial object, awaiting identification? In spite of the limited angular resolution provided by...

TheverysmallandtheverylargeareintimatelyconnectedinNature. Particle physics and astrophysics meet in fundamental questions: the structure and evolution of stars; their end and how this is manifested; how we think galaxies are created from matter we have yet to discover and why we believe the most energetic particles cannot come from the most distant universe. During the IV Escuela Mexicana de Astrof ?sica (EMA-2005), held in the beautiful colonial city of Morelia between 18 and 23 July 2005, we reviewed and explored the numerous connections between astrophysics and particle physics. The core...