Exploring the
Auger Observatory
with Google Earth

The Pierre Auger Observatory
is a very large array of detectors in
Argentina, with plans for a similar array
in the United States. Its aim is the study of
the rarest and most energetic particles in the
Universe: cosmic rays (most likely protons or
bare atomic nuclei) at extremely high energies,
whose origins are still a complete mystery despite
decades of intense investigations worldwide. These cosmic
rays can be studied indirectly by detecting the billions of high-
energy particles they produce in interactions with the Earth's
atmosphere. These come crashing down through the atmosphere
in a cascade, or extensive air shower, that can be detected by counters
scattered over a wide area, or else at night by detecting with sensitive
telescopes the sky glow (nitrogen fluorescence) they produce in traveling
through the atmosphere.

Physicists from 15 countries have been deploying detectors over an area of some 3000 km² in western Mendoza province, Argentina, to detect these rare air showers (while planning to also deploy a similar array in the Northern Hemisphere in Colorado, USA). To this end, some 1600 surface detectors ("water Cherenkov counters") have been deployed, on a grid with 1.5 km spacing. On hills at the edges of the array, at four different sites, nitrogen fluorescence telescopes are built and operated on dark clear nights, working in coincidence with the ground array. Also near the center of the array are two central laser facilities, used to fire laser shots into the sky at night to calibrate the response of the nitrogen fluorescence detectors. Finally, an observatory campus is located in the town of Malargue, at the edge of the array, with a data acquisition and storage station, office building, and assembly building (where surface detectors are prepared prior to deployment in the field).