Astrolabe Reef

Astrolabe Reef

Astrolabe Reef is near Mōtītī Island, 20 kilometres NE of Tauranga, off the Bay of Plenty coast in New Zealand. The reef, which breaks the water surface at low tide, is a renowned scuba diving spot that drops off to 37 metres (121 ft) in different parts. The reef was named by Jules Dumont d'Urville after his ship Astrolabe, when it nearly ran aground there on 16 February 1827.

Astrolabe

An astrolabe is an astronomical instrument dating to ancient times. It serves as a star chart and physical model of the visible half-dome of the sky. Its various functions also make it an elaborate inclinometer and an analog calculation device capable of working out several kinds of problems in astronomy. In its simplest form it is a metal disc with a pattern of wires, cutouts, and perforations that allows a user to calculate astronomical positions precisely. It is able to measure the altitude above the horizon of a celestial body, day or night; it can be used to identify stars or planets, to determine local latitude given local time, to survey, or to triangulate. It was used in classical antiquity, the Byzantine Empire, the Islamic Golden Age, the European Middle Ages and the Age of Discovery for all these purposes.

Reef

A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic (non-living) processes such as deposition of sand or wave erosion planing down rock outcrops. However, reefs such as the coral reefs of tropical waters are formed by biotic (living) processes, dominated by corals and coralline algae. Artificial reefs, such as shipwrecks and other man-made underwater structures, may occur intentionally or as the result of an accident. These are sometimes designed to increase the physical complexity of featureless sand bottoms to attract a more diverse range of organisms. They provide shelter to various aquatic animals which help prevent extinction. Another reason reefs are put in place is for aquaculture, and fish farmers who are looking to improve their businesses sometimes invest in them. Reefs are often quite near to the surface, but not all definitions require this.

astrolabe

Noun

1. An astronomical and navigational instrument for gauging the altitude of the Sun and stars.

reef

Noun

1. A chain or range of rocks, sand, or coral lying at or near the surface of the water.
2. A large vein of auriferous quartz; hence, any body of rock yielding valuable ore.

Noun

1. A portion of a sail rolled and tied down to lessen the area exposed in a high wind.
2. A reef knot.