Mount Wilson (California) a new Mt. Wilson Hotel. In 1908 a 60-inch (1524 mm) telescope was completed at the summit, and in 1910 the Solar Tower was erected. In 1913 the hotel burned down and was replaced by a second hotel that lasted until its demolition in 1966. The Toll Road opened to automobiles in 1912 and lasted until 1936. In 1917, the 100-inch Hooker Telescope was completed and saw first light and would be the world's largest telescope until the opening of the 200-inch Hale Telescope at Palomar Observatory in 1948. In 1919, American astronomer Edwin Hubble arrived at Mt. Wilson and,
Telescope Observatory]] to search for extraterrestrial life. [[File:Heao b.jpg|thumb|200px|[[Einstein Observatory]] was a space-based focusing optical X-ray telescope from 1978. ]] [[X-ray]] telescopes can use [[X-ray optics]], such as a [[Wolter telescope]]s composed of ring-shaped 'glancing' [[mirror]]s made of [[heavy metals]] that are able to reflect the rays just a few [[degree (angle)|degrees]]. The mirrors are usually a section of a rotated [[parabola]] and a [[hyperbola]], or [[ellipse]]. In 1952, [[Hans Wolter]] outlined 3 ways a telescope could be built using only this kind of mirror. Examples of an observatory using this type of telescope are the [[Einstein Observatory]], [[ROSAT]], and the