Hubble Space Telescope
Hubble Space Telescope (HST), first general-purpose orbiting observatory. Named after American astronomer Edwin P. Hubble , the Hubble Space Telescope was launched on April 24, 1990. The HST makes observations in the visible, infrared, and ultraviolet regions of the electromagnetic spectrum (see Electromagnetic Radiation ). The primary mirror of the HST has a diameter of 94.5 in (240 cm), and the optics of the telescope are designed so that, theoretically, when making a visible-light observation, the telescope can resolve astronomical objects that are at an angular distance of 0.05 arcsecond apart. In comparison, traditional large ground-based telescopes, under very good sky conditions, have an image resolution of about 0.5 arcsecond. Originally, the HST was equipped with five detectors: the Wide-Field Planetary Camera, the Faint Object Camera, the Faint Object Spectrograph, the High-Resolution Spectrograph, and the High Speed Photometer (see Spectroscopy ). It also has three fine guid...