Observatory

Observatory, in astronomy, a scientific site at which systematic observations of the sky are made. The first observatories were set up by ancient civilizations to regulate the calendar and predict eclipses and the rising of the sun and the moon. The sextant, quadrant, and astrolabe were devices for sighting positions of stars and planets. The invention of the telescope in the early 17th century revolutionized observational astronomy. Contemporary observatories contain optical or radio telescopes housed in rotating domes. Satellite telescopes allow X-ray observation.

See also: Telescope.