A frame containing solar cells that is attached to a spacecraft to turn the energy of sunlight into electrical power. Solar panels are usually mounted as opposite pairs, as on the Skylab space station and the Hubble Space Telescope. Probes such as Mariner 9 and Viking have four solar panels (two opposite pairs).

Golden solar arrays are lit from behind in this dramatic view of the Hubble Space Telescope as it sits in the space shuttle cargo bay during Hubble Servicing Mission 3 (STS-103). The Earth's atmosphere forms a bright streak between the telescope and the right solar panel.

Credit: NASA