
A gravitational-wave detector in Europe, operating as an interferometer alongside LIGO.Virgo is a gravitational-wave detector located near Pisa, Italy, and is one of the three major ground-based interferometers (along with the two LIGO detectors in the United States) that form a global network for observing ripples in spacetime. It is a Michelson interferometer with arms 3 kilometers long, designed to detect tiny changes in the length of its arms caused by passing gravitational waves. Virgo began operations in 2007 and underwent major upgrades to become Advanced Virgo, which joined the LIGO detectors in 2017 for the first joint observation run.
The Virgo interferometer was proposed in the 1980s by Alain Brillet and his team, with construction starting in 1996 and completion in 2003. It was designed and built by a collaboration of French and Italian institutes, and has been operating since 2007.
A gravitational wave passing through the detector stretches one arm while compressing the other, causing a differential change in the travel time of laser beams along the two arms. The interference pattern of the recombined beams shifts, and this shift is measured with extreme precision. To achieve the required sensitivity, the mirrors are suspended on sophisticated seismic isolation systems, and the entire apparatus operates in a vacuum to minimize noise.
Virgo, together with LIGO, has detected gravitational waves from merging black holes and neutron stars, enabling multi-messenger astronomy and tests of general relativity in strong-field regimes.
The Virgo detector is named after the Virgo cluster of galaxies, which is the nearest large galaxy cluster and a potential source of gravitational waves.






















