A globe is a spherical model of Earth, of some other celestial body, or of the celestial sphere. Globes serve purposes similar to some maps, but unlike maps, do not distort the surface that they portray except to scale it down. A model globe of Earth is called a terrestrial globe. A model globe of the celestial sphere is called a celestial globe.
A globe shows details of its subject. A terrestrial globe shows landmasses and water bodies. It might show nations and major cities and the network of latitude and longitude lines. Some have raised relief to show mountains and other large landforms. A celestial globe shows notable stars, and may also show positions of other prominent astronomical objects. Typically, it will also divide the celestial sphere into constellations.
The word globe comes from the Latin word globus, meaning "sphere". Globes have a long history. The first known mention of a globe is from Strabo, describing the Globe of Crates from about 150 BC. The oldest surviving terrestrial globe is the Erdapfel, wrought by Martin Behaim in 1492. The oldest surviving celestial globe sits atop the Farnese Atlas, carved in the 2nd century Roman Empire.
Flat maps are created using a map projection that inevitably introduces an increasing amount of distortion the larger the area that the map shows. A globe is the only representation of the Earth that does not distort either the shape or the size of large features – land masses, bodies of water, etc.
The Earth's circumference is quite close to 40 million metres. Many globes are made with a circumference of one metre, so they are models of the Earth at a scale of 1:40 million. In imperial units, many globes are made with a diameter of one foot [ citation needed ] (about 30 cm), yielding a circumference of 3.14 feet (about 96 cm) and a scale of 1:42 million. Globes are also made in many other sizes.
Some globes have surface texture showing topography or bathymetry. In these, elevations and depressions are purposely exaggerated, as they otherwise would be hardly visible. For example, one manufacturer produces a three dimensional raised relief globe with a 64 cm (25 in) diameter (equivalent to a 200 cm circumference, or approximately a scale of 1:20 million) showing the highest mountains as over 2.5 cm (1 in) tall, which is about 57 times higher than the correct scale of Mount Everest.
Most modern globes are also imprinted with parallels and meridians, so that one can tell the approximate coordinates of a specific place. Globes may also show the boundaries of countries and their names.
Many terrestrial globes have one celestial feature marked on them: a diagram called the analemma, which shows the apparent motion of the Sun in the sky during a year.
Globes generally show north at the top, but many globes allow the axis to be swiveled so that southern portions can be viewed conveniently. This capability also permits exploring the Earth from different orientations to help counter the north-up bias caused by conventional map presentation.
Celestial globes show the apparent positions of the stars in the sky. They omit the Sun, Moon and planets because the positions of these bodies vary relative to those of the stars, but the ecliptic, along which the Sun moves, is indicated.
The sphericity of the Earth was established by Greek astronomy in the 3rd century BC, and the earliest terrestrial globe appeared from that period. The earliest known example is the one constructed by Crates of Mallus in Cilicia (now Çukurova in modern-day Turkey), in the mid-2nd century BC.
No terrestrial globes from Antiquity or the Middle Ages have survived. An example of a surviving celestial globe is part of a Hellenistic sculpture, called the Farnese Atlas, surviving in a 2nd-century AD Roman copy in the Naples Archaeological Museum, Italy.
Early terrestrial globes depicting the entirety of the Old World were constructed in the Islamic world.According to David Woodward, one such example was the terrestrial globe introduced to Beijing by the Persian astronomer, Jamal ad-Din, in 1267.
The earliest extant terrestrial globe was made in 1492 by Martin Behaim (1459–1537) with help from the painter Georg Glockendon.Behaim was a German mapmaker, navigator, and merchant. Working in Nuremberg, Germany, he called his globe the "Nürnberg Terrestrial Globe." It is now known as the Erdapfel. Before constructing the globe, Behaim had traveled extensively. He sojourned in Lisbon from 1480, developing commercial interests and mingling with explorers and scientists. He began to construct his globe after his return to Nürnberg in 1490.
Another early globe, the Hunt–Lenox Globe, ca. 1510, is thought to be the source of the phrase Hic Sunt Dracones, or “Here be dragons”. A similar grapefruit-sized globe made from two halves of an ostrich egg was found in 2012 and is believed to date from 1504. It may be the oldest globe to show the New World. Stefaan Missine, who analyzed the globe for the Washington Map Society journal Portolan, said it was “part of an important European collection for decades.”After a year of research in which he consulted many experts, Missine concluded the Hunt–Lenox Globe was a copper cast of the egg globe.
A facsimile globe showing America was made by Martin Waldseemueller in 1507. Another "remarkably modern-looking" terrestrial globe of the Earth was constructed by Taqi al-Din at the Constantinople Observatory of Taqi ad-Din during the 1570s.
The world's first seamless celestial globe was built by Mughal scientists under the patronage of Jahangir.
Globus IMP, electro-mechanical devices including five-inch globes have been used in Soviet and Russian spacecraft from 1961 to 2002 as navigation instruments. In 2001, the TMA version of the Soyuz spacecraft replaced this instrument with a digital map.
In the 1800s small pocket globes (less than 3 inches) were status symbols for gentlemen and educational toys for rich children.
Traditionally, globes were manufactured by gluing a printed paper map onto a sphere, often made from wood.
The most common type has long, thin gores (strips) of paper that narrow to a point at the poles,small disks cover over the inevitable irregularities at these points. The more gores there are, the less stretching and crumpling is required to make the paper map fit the sphere. This method of globe making was illustrated in 1802 in an engraving in The English Encyclopedia by George Kearsley .
Modern globes are often made from thermoplastic. Flat, plastic disks are printed with a distorted map of one of the Earth's Hemispheres. This is placed in a machine which molds the disk into a hemispherical shape. The hemisphere is united with its opposite counterpart to form a complete globe.
Usually a globe is mounted so that its spin axis is 23.5° (0.41 rad) from vertical, which is the angle the Earth's spin axis deviates from perpendicular to the plane of its orbit. This mounting makes it easy to visualize how seasons change.
Sorted in decreasing sizes:
In astronomy and navigation, the celestial sphere is an abstract sphere that has an arbitrarily large radius and is concentric to Earth. All objects in the sky can be conceived as being projected upon the inner surface of the celestial sphere, which may be centered on Earth or the observer. If centered on the observer, half of the sphere would resemble a hemispherical screen over the observing location.
In cartography, a map projection is a way to flatten a globe's surface into a plane in order to make a map. This requires a systematic transformation of the latitudes and longitudes of locations from the surface of the globe into locations on a plane. All projections of a sphere on a plane necessarily distort the surface in some way and to some extent. Depending on the purpose of the map, some distortions are acceptable and others are not; therefore, different map projections exist in order to preserve some properties of the sphere-like body at the expense of other properties. Every distinct map projection distorts in a distinct way, by definition. The study of map projections is the characterization of these distortions. There is no limit to the number of possible map projections. Projections are a subject of several pure mathematical fields, including differential geometry, projective geometry, and manifolds. However, "map projection" refers specifically to a cartographic projection.
An equatorial bulge is a difference between the equatorial and polar diameters of a planet, due to the centrifugal force exerted by the rotation about the body's axis. A rotating body tends to form an oblate spheroid rather than a sphere.
An armillary sphere is a model of objects in the sky, consisting of a spherical framework of rings, centred on Earth or the Sun, that represent lines of celestial longitude and latitude and other astronomically important features, such as the ecliptic. As such, it differs from a celestial globe, which is a smooth sphere whose principal purpose is to map the constellations. It was invented separately in ancient Greece and ancient China, with later use in the Islamic world and Medieval Europe.
The earliest documented mention of the spherical Earth concept dates from around the 5th century BC, when it was mentioned by ancient Greek philosophers. It remained a matter of speculation until the 3rd century BC, when Hellenistic astronomy established the spherical shape of the Earth as a physical fact and calculated the Earth's circumference. The paradigm was gradually adopted throughout the Old World during Late Antiquity and the Middle Ages. A practical demonstration of Earth's sphericity was achieved by Ferdinand Magellan and Juan Sebastián Elcano's circumnavigation (1519–1522).
Martin Behaim, also known as Martin von Behaim and by various forms of Martin of Bohemia, was a German textile merchant and cartographer. He served Joao II of Portugal as an adviser in matters of navigation and participated in a voyage to West Africa. He is now best known for his Erdapfel, the world's oldest surviving globe, which he produced for the Imperial City of Nuremberg in 1492.
In astronomy, a planisphere is a star chart analog computing instrument in the form of two adjustable disks that rotate on a common pivot. It can be adjusted to display the visible stars for any time and date. It is an instrument to assist in learning how to recognize stars and constellations. The astrolabe, an instrument that has its origins in Hellenistic astronomy, is a predecessor of the modern planisphere. The term planisphere contrasts with armillary sphere, where the celestial sphere is represented by a three-dimensional framework of rings.
The Voskhod was a spacecraft built by the Soviet Union's space program for human spaceflight as part of the Voskhod programme. It was a development of and a follow-on to the Vostok spacecraft. Voskhod 1 was used for a three-man flight whereas Voskhod 2 had a crew of two. They consisted of a spherical descent module, which housed the cosmonauts, and instruments, and a conical equipment module, which contained propellant and the engine system. Voskhod was superseded by the Soyuz spacecraft in 1967.
The angular diameter, angular size, apparent diameter, or apparent size is an angular measurement describing how large a sphere or circle appears from a given point of view. In the vision sciences, it is called the visual angle, and in optics, it is the angular aperture. The angular diameter can alternatively be thought of as the angle through which an eye or camera must rotate to look from one side of an apparent circle to the opposite side. Angular radius equals half of the angular diameter.
The globus cruciger, also known as "the orb and cross", is an orb surmounted by a cross. It has been a Christian symbol of authority since the Middle Ages, used on coins, in iconography, and with a sceptre as royal regalia.
The earliest known world maps date to classical antiquity, the oldest examples of the 6th to 5th centuries BCE still based on the flat Earth paradigm. World maps assuming a spherical Earth first appear in the Hellenistic period. The developments of Greek geography during this time, notably by Eratosthenes and Posidonius culminated in the Roman era, with Ptolemy's world map, which would remain authoritative throughout the Middle Ages.
The Erdapfel is a terrestrial globe produced by Martin Behaim from 1490–1492. The Erdapfel is the oldest surviving terrestrial globe. It is constructed of a laminated linen ball in two halves, reinforced with wood and overlaid with a map painted by Georg Glockendon. The map was drawn on paper, which was pasted on a layer of parchment around the globe.
The Hunt–Lenox Globe or Lenox Globe, dating from 1504, is the second- or third-oldest known terrestrial globe, after the Erdapfel of 1492. It is housed by the Rare Book Division of the New York Public Library.
The Globus Jagellonicus or Jagiellonian globe, probably made in northern Italy or the south of France and dated to around 1510, is by some considered to be the oldest existing globe to show the Americas. It bears a striking resemblance to the Hunt–Lenox Globe, also tentatively dated to 1510 which is the second or third oldest known terrestrial globe, after the Erdapfel of Martin Behaim, made in Nuremberg in 1492, the year before Columbus' discovery became known in March 1493, and thus without the new continents. Globes made by Martin Waldseemüller in 1507 already showed America.
Planetary cartography, or cartography of extraterrestrial objects (CEO), is the cartography of solid objects outside of the Earth. Planetary maps can show any spatially mapped characteristic for extraterrestrial surfaces.
The Globe Museum is a museum in the Palais Mollard, Vienna, Austria, part of the Austrian National Library. It was opened in 1956, and is the only public museum in the world devoted to globes, being three-dimensional models of Earth or other celestial bodies, or spherical representations of the celestial sphere.
Globus IMP instruments were spacecraft navigation instruments used in Soviet and Russian crewed spacecraft. The IMP acronym stems from the Russian expression Indicator of position in flight, but the instrument is informally referred to as the Globus. It displays the nadir of the spacecraft on a rotating terrestrial globe. It functions as an on board, autonomous indicator of the spacecraft's location relative to Earth coordinates. An electro-mechanical device in the tradition of complex post-World War II clocks such as master clocks, the Globus IMP instrument incorporates hundreds of mechanical components common to horology. This instrument is a mechanical computer for navigation akin to the Norden bombsight. It mechanically computes complex functions and displays its output through mechanical displacements of the globe and other indicator components. It also modulates electric signals from other instruments.
A variety of symbols or iconographic conventions are used to represent Earth, whether in the sense of planet Earth, or the inhabited world, or as a classical element. Representations of the globe of Earth, either with an indication of the shape of the continents or with a representation of meridians and parallels remains a common pictographic convention to express the notion of "worldwide, global". The modern astronomical symbol for Earth as a planet uses a circle with a cross is 🜨.
Earth's circumference is the distance around the Earth. Measured around the poles, the circumference is 39,940.653 km (24,817.971 mi). Measured around the equator, it is 40,075.017 km (24,901.461 mi).
The Ostrich Egg Globe or Da Vinci Globe is an Italian Renaissance object of historical importance. It dates from 1504 and was discovered by the globe and map collector S. Missinne in London in 2012. It is the prototype (model) for the red copper cast Hunt-Lenox Globe at the New York Public Library.
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