... The choice of which type of electricity is called "positive" and which "negative" was made around 1750 by Ben Franklin, early American scientist and man of many talents (the stamp on the left commemorates his role as first US postmaster--and colonial postmaster before that). ... Franklin knew of two types of electric charge, depending on the material one rubbed. ... Later, when electric batteries were discovered, scientists naturally assigned the direction of the flow of current to be from (+) to (-...
... Faraday's Lines of Force (field lines) . Faraday's Disk Dynamo . ... The Earth's Dynamo . ... Magnetic Storms and Ring Currents . The Magnetosphere . ... Chronology of Geomagnetism . ... 1581 Robert Norman publishes "The Newe Attractive," . ... 1832 Faraday tries to detect a dynamo current in water flowing in the Earth's field. ... magnetic storm. ... 1903 Birkeland proposes the existence of "polar magnetic storms," He also . ... 1919 Joseph Larmor proposes that magnetic fields of sunspots . ...
... NASA Lunar Orbiter . ... The Lunar Prospector is designed for a low-polar orbit investigation of the Moon, including mapping of surface composition and possible polar ice deposits, measurements of magnetic and gravity fields, and study of lunar outgassing events. Data from the 1- to 3-year mission will allow construction of a detailed map of the surface composition of the Moon, and will improve our understanding of the origin, evolution, current state, and resources of the Moon. ...