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A dome is a common structural element of architecture that resembles the hollow upper half of a sphere. Domes do not have to be perfectly spherical in cross-section, however; a dome may be a section through an ellipse. If the baseline is taken parallel to the shorter of an ellipse's two diameters, a tall dome results, giving a sense of upward reach. A section across the longer axis results in a low dome, capping the volume instead. A very low dome is a saucer dome (see below). All the surfaces of any dome are curved. A spectacular innovation, one that is at the heart of Baroque style, is the oval dome, of Bernini and Borromini which gives axial direction and movement to the space beneath it.

Three domes that have been disproportionately influential in later architecture have been those of Hagia Sophia in Constantinople, the Dome of the Rock in Jerusalem and the Pantheon in Rome. In Western architecture, the most influential domes built since the Renaissance have been those of St. Peter's Basilica in Rome and Jules Hardouin-Mansart's dome at Les Invalides in Paris. The dome of St. Paul's Cathedral in London was the inspiration for the United States Capitol in Washington, which in turn inspired domes of most of the US state capitols. See further influential domes below.

In the 20th century, thin "eggshell" domes of pre-stressed concrete by architect-engineers such as Nervi opened new directions in fluid vaulted spaces enclosed beaneath freeform domed space which now might be supported merely at points rather than in the traditional constricting ring.

Contents 1 Characteristics 1.1 Saucer dome 1.2 Onion dome 2 Famous domes 3 Xanadu House 4 See also 5 External links

Characteristics

A dome can be considered as an arch which has been rotated around its vertical axis. As such, domes have a great deal of structural strength. A small dome can be constructed of ordinary masonry, held together by friction and compressive forces. Larger domes built after Brunelleschi dome in Florence have all been double domes, with inner and outer shells.

The concave triangular sections of vaulting that provide the transition between a dome and the square base on which it is set and transfer the weight of the dome are called pendentives. (A less sophisticated version of a pendentive is a squinch.) Under the dome illustrated at left, the pendentives bear circular medallions in bas relief.

A half-dome forms the head of an exedra or its smaller version, a niche. In Late Antiquity, the exedra developed into the apse, with separate developments in Romanesque and Byzantine practice.

Many domes are topped by a lantern, a structure with openings (or windows) to admit light in the cupola.

Many sports stadiums are domed, especially in climates that have widely-variable summer and winter weather. The first such stadium was the Astrodome in Houston, Texas. A major improvement to the domed stadium was accomplished with the construction of SkyDome in Toronto, Ontario, the first domed stadium with a retractable roof.

Saucer dome

A saucer dome is the architectural term used for a low pitched shallow dome. Described geometrically as being of circular base and a segmental (less than a semicircle) section.

Gaining in popularity from the 18th century onwards, the saucer dome is often a feature of interior design, viewed from below it resembles the shallow concave shape of a saucer. The dome itself being often contained in the space between ceiling and attic is invisible externally. These domes are usually decorated internally by ornate plaster-work, occasionally they are frescoed.

They are seen occasionally externally in Byzantine churches and mosques.

Onion dome

Main article: onion dome.

The onion dome resembles more than half of a sphere, exemplified by Saint Basil's Cathedral in Moscow and the Taj Mahal. They are found mostly in eastern architecture, particularly in Russia, Turkey, the Middle East, and even India.

Famous domes

Listed in order of their completion:

• 27 BC - The Pantheon, Rome, Italy.
• 537 - Hagia Sophia, Constantinople, Turkey.
• 691 - Dome of the Rock, Jerusalem.
• 1312 - Dome of Soltaniyeh, Iran.
• 1436 - The Duomo, Florence, Italy.
• 1502 - The Tempietto, Rome, Italy.
• 1593 - St. Peter's Basilica, Rome, Italy.
• 1616 - The Blue Mosque, Istanbul, Turkey.
• 1653 - The Taj Mahal, Agra, India.
• 1659 - Gol Gumbaz, Bijapur Karnataka India
• 1708 - Les Invalides, Paris, France.
• 1708 - St Paul's Cathedral, London, England.
• 1749 - The Radcliffe Camera, Oxford, England.
• 1858 - St Isaac's Cathedral, St Petersburg, Russia.
• 1850s - The United States Capitol, Washington, DC, USA.
• 1965 - The Astrodome, Houston, TX, USA.
• 2000 - The Millennium Dome, London, England.

Xanadu House

The Xanadu House was a home that used the concept of domes heavily in its shape and design. The home was one of the first non-indigenous homes to use curved surfaces throughout the exterior and interior.

See also

• Geodesic dome
• Cupola
• Concrete dome
• Doming technique
• Rotunda
• Dome (Slang)

External links

• The Dome of Brunelleschi, Florence virtual reality movie and pictures

This article is based on the article "Domes" from Wikipedia - the free encyclopedia created and edited by online user community. This article is distributed under the terms of GNU Free Documentation License. Here you find the list of authors of this article. The article can only edited within Wikipedia. Edit this article in Wikipedia.

An observatory is a location used for observing terrestrial and/or celestial events. Astronomy, astrology, climatology, geology, meteorology and volcanology are examples of disciplines for which observatories have been constructed. Historically, observatories were as simple as containing a sextant (for measuring the distance between stars) or Stonehenge (which has some alignments on astronomical phenomena). Modern astronomical observatories typically contain one or more permanently mounted telescopes contained in buildings with a rotating or removable dome. Beginning in the 1940's, radio telescopes were built and began to detect significant radio sources in the universe. Such an instrument, or a collection of them, with outbuildings for such things as control centres, data reduction centers, and maintenance are called radio observatories. Some of the major radio observatories are at Socorro, in New Mexico, USA, Jodrell Bank in the UK, Arecibo, Puerto Rico and Parkes in New South Wales, Australia. Major optical observatories include Mauna Kea, HI, USA, Roque de los Muchachos Observatory in the Canary Islands, Paranal Observatory in Chile and Kitt Peak observatory in the USA. The largest observatory in the equatorial belt is Observatorio Nacional de Llano del Hato in Venezuela. Within the last twenty years, many space-based observatories have been launched, introducing a new use of the term.

See also

• Volcano observatory
• Space observatory
• Timeline of telescopes, observatories, and observing technology
• list of observatories

This article is based on the article "Observatories" from Wikipedia - the free encyclopedia created and edited by online user community. This article is distributed under the terms of GNU Free Documentation License. Here you find the list of authors of this article. The article can only edited within Wikipedia. Edit this article in Wikipedia.