During orbital verification the Far Ultraviolet Spectroscopic Explorer obtained spectra of the terrestrial day airglow between 905 and 1184 ¿ from an altitude of 766 km. The spectrographs have three apertures that can simultaneously record the atmospheric emissions with limiting instrumental spectral resolutions of approximately 0.4, 0.05, and 0.03 ¿. Seven orbits were obtained of observations of the sunlit Earth and disclose a wealth of emissions resulting from the electron impact excitation of N2 in addition to emissions of O I, N I, and N II produced by both photoelectron impact and by photodestructive excitation and ionization of thermospheric O and N2 by extreme ultraviolet solar radiation. The argon resonance transitions are unambiguously identified as are previously unreported transitions between highly excited energy levels of O+. These spectra have the highest spectral resolution and sensitivity in this spectral range to date and will provide valuable input to the interpretation of lower resolution spectra from current and future Earth remote sensing missions. ¿ 2001 American Geophysical Union