The Infrared Space Observatory

The first true infrared observatory in space, ESA's Infrared Space Observatory (ISO), was launched 17 November 1995. Since one and a half years, it has made more than 15,000 observations with its four versatile instruments: a camera, a photo-polarimeter and two spectrometers. This paper presents an overview of the satellite, its payload, the operations of the observatory and gives an outlook of the events to come. This revised version was published online in July 2006 with corrections to the Cover Date.