BUENOS AIRES (AFP) -– Scientists in western Argentina were set to inaugurate on Friday the world's largest astronomical observatory, hoping to unlock the mysteries of high energy cosmic rays that bombard the Earth.

The opening ceremony meant the vast Pierre Auger Observatory will begin realizing ""its potential for the next 20 years,"" astronomer team member Beatriz Garcia told AFP.
Construction for the international effort -- involving a team of more than 370 scientists and engineers from 17 countries -- began in 1999, in an elaborate joint project to better understand the particles discovered by the facility's namesake, French physicist Pierre Auger, in 1938.
With the launch of the observatory's detection systems, science has ""taken a big step forward in solving the mystery of the nature and origin of the highest-energy cosmic rays,"" said Nobel Prize winner James Cronin, of the University of Chicago, who conceived the Pierre Auger Observatory, along with Alan Watson of the University of Leeds.
""The age of cosmic-ray astronomy has arrived,"" he said. The inauguration paves the way for a second phase of construction that will include building a similar instrument in the US state of Colorado.
To observe the cosmic ray showers -- high-energy particles present in universe that bombard the Earth -- the Pierre Auger uses a collection of 1,600 particle detectors placed 1.5 kilometers (one mile) apart, in a grid spread across 3,000 square kilometers (1,200 square miles).
On top of this detection system, scientists will turn the observatory into the most powerful galaxial observation instrument ever built with an additional 24 telescopes, to record emissions of light from the particle shower.
Cosmic particles amount to microscopic protons and atomic nuclei, which whiz across the vast expanse of the universe, approaching the speed of light.