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<b>The Virgo Cluster of Galaxies in the Making</b><br /><br />LINK<br /><br />At a distance of approximately 50 million light-years, the Virgo Cluster is the nearest galaxy cluster. It is located in the zodiacal constellation Virgo (The Virgin) and contains many hundreds of galaxies, ranging from giant and massive elliptical galaxies and spirals like our own Milky Way, to dwarf galaxies, hundreds of times smaller than their big brethren. French astronomer Charles Messier entered 16 members of the Virgo cluster in his famous catalogue of nebulae. An image of the core of the cluster obtained with the Wide Field Imager camera at the ESO La Silla Observatory was published last year as PR Photo 04a/03. <br /><br />Clusters of galaxies are believed to have formed over a long period of time by the assembly of smaller entities, through the strong gravitational pull from dark and luminous matter. The Virgo cluster is considered to be a relatively young cluster because previous studies have revealed small "sub-clusters of galaxies" around the major galaxies Messier 87, Messier 86 and Messier 49. These sub-clusters have yet to merge to form a denser and smoother galaxy cluster. <br /><br />Recent observations have shown that the so-called "intracluster" space, the region between galaxies in a cluster, is permeated by a sparse "intracluster population of stars", which can be used to study in detail the structure of the cluster. <br /><br />The first discoveries of intracluster stars in the Virgo cluster were made serendipitously by Italian astronomer, Magda Arnaboldi (Torino Observatory, Italy) and her colleagues, in 1996. In order to study the extended halos of galaxies in the Virgo cluster, with the ESO New Technology Telescope at La Silla, they searched for objects known as "planetary nebulae" [3]. <br /><br />Planetary nebulae (PNe) can be detected out to large distances from their strong emission l