Charting the Indian Ocean from Zanzibar to Sumatra
Cartography ---The science and practice of projecting by various methods an area of the earth’s surface on a flat plane, such as a sheet of parchment or paper.
Planisphere ---The projection of the celestial sphere on a plane. It shows which stars (constellations, but not planets) will be visible during any time of night for any time of year. It often goes by the name of “star finder.”
Ptolemaic system ---The belief that the earth is the center of the universe and that all planets revolve around it.
Astrolabe ---An astronomical instrument that measures the height above the horizon of celestial bodies (in particular, the sun or a star). Especially at sea, this technique enables seamen to estimate their approximate latitude.
Portolano (portolani, pl.) ---Nautical charts made by seamen that gave information about navigation and directions to ports.
Longitude (meridians) ---Lines that run vertically north to south around the surface of the earth, through the Poles. They determine location east and west of the prime meridian, which is zero degrees at Greenwich, England.
Latitude (parallels) ---Lines that run horizontally east and east around the surface of the earth. Lines of latitude determine location north and south on the globe. The equator is the longest line of latitude.
Rhumb-line ---A line across the surface of a globe that intersects all meridians (lines of longitude) at the same angle.
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© 2002 Penelope Campbell. All rights reserved.