Asteroid

Asteroid
A rocky orbiting the sun. Most asteroids are distributed between the orbits of Mars and Jupiter, although some have eccentric orbits that intersect the Earth’s.

There are may be as many as a million with diameters in excess of a kilometer.

The first to be discovered – by Piazzi in 1801 – was the largest, Ceres.

Three more, including Pallas and Vesta, were discovered in the same decade. Eros was discovered on 1898, was the first whose orbit was sufficiently eccentric to extend almost as far as the Earth’s.

The discoverer of Pallas and Vesta, Heinrich Olbers, suggested that the asteroids might be the debris of a*planet shattered by some kind of disaster.

The notion was encouraged by Bode’s law, a mathematical sequence published in the 1770s that correspond to the proportional orbital distances of the known planets, except for a gap between Mars and Jupiter.

The alternate explanation of their origin – preferred by most twentieth century theorists – is that a scattered ring of matter never condensed into a planet for lack of an appropriate nucleus.

Most asteroids are almost entirely metallic, their dominant components being nickel and iron, but some smaller ones are formed out of stony materials like those in the Earths crust, including some carbon compounds.
Asteroid

Static Electricity

Static Electricity
The scientific study of electricity and magnetism began with William Gilbert. Born in Colchester and educated at Cambridge, Gilbert was successful medical practitioner who became physician to Queen Elizabeth I in 1600.

In the same year he also published his books De Magnete, which recorded his conclusions from many year’s spare-time work on electrostatics and magnetism and for the first time, drew a clear distinction the two phenomena.

In a very dangerous experiment the American statesmen Benjamin Franklin showed that a kite flown in a thunderstorm became electrically charged.

His German contemporary Georg Wilhelm Richman was less fortunate: he was killed trying the same experiment at St Petersburg in 1753.

Franklin also studied the discharge of electricity from objects of different shapes, he suggested protection of buildings by lightning conductors and in the lights of his discharge experiments said that they should be pointed.

The discovery of the electric current, about 1800, did not end he story of static electricity. Two important machines of the nineteenth century were Armstrong’s hydroelectric machine and the Wimshurst machine.

William Armstrong was a solicitor and amateur scientist who founded an engineering business in Newcastle upon Tyne.

His attention was drawn to a strange effect noticed by an engine driver on a colliery railway. The driver experienced ‘a curious pricking sensation’ when he touch the steam valve on a leaking boiler.

Armstrong found that steam, issuing from small hole, became electrically charged.

He then built a machine with an iron boiler on glass legs and a hard wood nozzle through which steam could escape.

He found the steam was positively charged and he then made a larger machine which was demonstrated in London producing sparks more than half a meter long.

A War Office committee on mines suggested in 1857 that Armstrong’ machine, with its very high voltage output, could be used for detonating mines.

In practice magneto-electric machines were soon available, and Armstrong’s machine never saw a practical use.

During the nineteenth century numerous machines were made which multiplied static electric charges by induction and collected them in Leyden jars or other capacitors.
Static Electricity