Observatories

An Observatory is any facility specifically for making celestial observations and measurements. Some structures such as Stonehenge may well have been used for observations. The observatory proper evolved from Babylonian constructions set up for astrological observation from about 750 BC, and reached a high state of scientific development in the late 16th century with the observatories of Tycho Brahe. The observatory as a telescope housing dates from the 17th century; notable examples are Copenhagen Observatory (1642), Paris Observatory (1671) and Greenwich Observatory (1675), founded principally for geodesy and navigation.

The era of observatories built for scientific research rather than the practical needs of the state began in the 18th century. It brought about the development of large facilities such as Lord Rosse’s observatory in Ireland, and Lick Observatory in California (1888) and Yerkes Observatory in Wisconsin (1897) with their great refractors. The first half of the 20th century saw a continuing dominance of the USA in large telescope building with Mount Wilson Observatory’s 100-inch (2.5-m) and Palomar Observatory‘s 200-inch (5-m) reflectors, completed in 1917 and 1948, respectively.

With the arrival of frequent and rapid air travel in the 1960s, optical astronomers were no longer restricted in where to locate their observatories, and the next decade saw a proliferation of telescopes in the 4-metre class on excellent remote sites. The post-war years also saw a growth in the number of large radio telescopes, and the first proposals for observatories in space to overcome the limited range of wavelengths available to astronomers on the Earth’s surface.

Today, the turn-of-the-century boom in 8–10-metre class telescopes is well under way, and a new generation of optical-astronomy institutions such as the Gemini Observatory and the W.M. Keck Observatory is emerging. The modern observatory is often far from its telescopes, either because of the geographical remoteness of the observing site or because the observatory operates a space facility.

Increasingly important are observatories dedicated to popular astronomy. These range from the private observatories of amateur astronomers (some of which, like their 18th-century forebears, challenge the smaller professional observatories in the quality of their equipment) to major educational facilities such as the Faulkes Telescope. Public education and outreach is giving a new lease of life to the older facilities of professional observatories, whose working astronomers now use newer telescopes elsewhere. A good example is the 0.91-m (36-in.) reflector of the Royal Observatory, Edinburgh (1928), which is now the centerpiece of the observatory’s Visitor Centre.

Questions to Ponder:

• What is the difference between an Observatory and a Planetarium?
• How does 'location' affect an Observatory? Why can’t Observatories be built anywhere?