The Infrared Space Observatory (ISO) was a space telescope for infrared light designed and operated by the European Space Agency (ESA).

Planning started in 1979. It was finally launched into space in November 1995 and operated until it ran out of liquid helium in May 1998; 8 months longer than the original goal.

An overview about the project and a gallery of pictures can be found on its web site: http://www.iso.vilspa.esa.es