Globe

Painting a globe

Aglobeis ascale modelwith the shape of asphere.Globes can be scale models of theEarth(terrestrial globes) or of other planets. Globes can also be models of thecelestial sphere(celestial globes). The English word "globe" comes from theLatin:globus,meaningroundmass orsphere.

Most globes aremapsof theEarth.They have the advantage of avoiding the distortions of flatmap projections. The most common types are political and physical. Political globes show countries. Physical globes showlandscapelikemountainsandrivers.Some globes arestar charts and some are maps of distant worlds.

Globalas anadjectiveis used to mean the entireworldrather than any special place on the Earth. It is also used in fields likecomputersto mean dealing with a whole largersystem,rather than its individual little parts.

History

Aureus(gold coin) of theRoman emperorCarus,with apersonificationofVictorystanding on a terrestrial globe

That the Earth is aspherewas established byHellenistic astronomyin the 3rd centuryBC.The terrestrial globe appeared in that period.Now, there are no terrestrial globes from Classical Antiquity or theMiddle Agesin existence.The first example of terrestrial globe known was the one theancient GreekCrates of Mallusmade in the middle of the 2ndcenturyBC.The GreekgeographerStrabowrote about Crates's terrestrial globe during the early years of theRoman Empire.

A celestial globe fromClassical Antiquityis in theNaples National Archaeological Museum,Italy.The globe is part of asculpture– the globe is held up by astatueofAtlas,aTitanfromGreek mythology.Theancient Romansmade the globe and statue in the 2ndcenturyAD.They may have copied the sculpture fromHellenistic art(art of theancient Greektype) from theHellenistic period(the 1st, 2nd, and 3rd centuries BC). The sculpture's name is theFarnese Atlas.

Early globes of the Earth that show all of theOld Worldwere constructed in theIslamic Golden Age.One such example was made in the 9th century AD byMuslimgeographersandcartographersworking under theAbbasidcaliph,al-Ma'mun.Another example was the globe introduced toBeijingby the Persian astronomer,Jamal ad-Din,in 1267.

Olivier van Deuren:A Young Astronomer

Martin Behaimdesigned a globe in 1492, inNuremberg,Bavaria(Germany).Georg Glockendonwas the artist who created the actual map drawings following Behaim's specifications.This globe is the oldest terrestrial globe still in existence.A copy of the globe showing America was made byMartin Waldseemuellerin 1507. Another early globe, theHunt-Lenox Globe,ca. 1507, is thought to be the source of the phrase "Here be dragons".Another" remarkably modern-looking "globe of the Earth was made inConstantinople(Istanbul) byTaqi al-Dinat hisConstantinople Observatoryduring the 1570s.

Manufacture

Gores for making a globe ofMars,with polar disks, 1892

Mass-produced globes are typically covered by a printed paper map. The most common type has long, thingores(strips) of paper. These strips narrow to a point at theNorth Poleand theSouth Pole.Then a small disk is used to paper over the irregularities at the poles. The more gores there are, the less stretching and crumpling is needed to make the paper map fit the sphere.

From a geometric point of view, all points on a sphere are the same. One could select any point on the planet, and create a paper map that covers the globe with strips that come together at that point and the opposite point.

A globe that represents the Earth is usually mounted at a 23.5° angle onbearings.This mounting represents theaxial tiltof the spinning planet, in relation to theSun.This makes it easy to visualize howdaysandseasonschange.