Johannes Kepler was born on Dec. 27, 1571, in the Swabian town of Weil. His father, Heinrich Kepler,

A German astronomer and mathematician, considered one of the founders of modern astronomy. Using positional data carefully amassed by Tycho Brahe , Kepler formulated 4 star hotels england his famous three laws (see Kepler's laws of planetary motion ), including the crucial realization that planetary orbits are ellipses not circles. Born in Weil der Stadt, southwest Germany, he studied at the University of Tübingen and, as a graduate, was tutored by Michael Maestlin who introduced him to the heliocentric concepts of Copernicus . In 1597 he published The Cosmographic Mystery in which (revealing his medieval mystical bent) he argued that the distances of the planets from the Sun in the Copernican system were determined by the five regular solids, 4 star hotels england if one supposed that a planet's orbit was circumscribed about one solid and inscribed in another. Except for Mercury, Kepler's construction gave surprisingly 4 star hotels england accurate results. Because of the mathematical skills shown in this volume, he was invited by Tycho Brahe to Prague to become his assistant and to calculate new orbits for the planets from Tycho's observations. When Tycho died, in 1601, Kepler was appointed his successor as Imperial Mathematician, the most prestigious job in mathematics in Europe. In Prague, Kepler published Astronomia pars Optica (The optical part of astronomy, 1604), in which he dealt with refraction and gave the first modern explanation of the workings of the eye; De Stella Nova (Concerning the new star, 1606) on the "new" star that had appeared in 1604 (see Kepler's Star ); and Astronomia Nova (New astronomy, 1609), which contained his first two laws (planets move in elliptical orbits with the Sun at one focus, and a planet sweeps out equal areas in equal times). In 1610 Kepler heard about Galileo 's discoveries with the telescope and wrote a long letter of support, which he published as Dissertatio cum Nuncio Sidereo (Conversation with the sidereal messenger). Later that year, he presented his own observations ofJupiter's moons. These writings gave tremendous support 4 star hotels england to Galileo, whose discoveries were being widely doubted and denounced by church authorities. Kepler went on to provide the beginning of a theory of the telescope in his Dioptrice 4 star hotels england (1611), the title being a word he coined himself. A couple of years later he wrote De Vero Anno quo Aeternus Dei Filius Humanam Naturam in Utero Benedictae Virginis Mariae Assumpsit (Concerning the true year in which the son of God assumed a human nature in the uterus of the blessed Virgin Mary), 4 star hotels england arguing that the Christian calendar was out by five years, and that Jesus had been born in 4 B.C. (a conclusion now widely accepted). Between 1617 and 1621 he published Epitome Astronomiae Copernicanae (Epitome 4 star hotels england of Copernican astronomy), which became the most influential introduction to heliocentric astronomy of the time. In his Harmonice Mundi (Harmony of the world, 1619), he derived the heliocentric distances of the planets and their periods from considerations of musical 4 star hotels england harmony, and presented his third law, relating the periods of the planets to their mean orbital radii. His Tabulae Rudolphinae (Rudolphine tables, 1627), based on Tycho's observations and calculated according to the elliptical astronomy, were used into the eighteenth century. This was not quite the last of Kepler's published work, however. His Somnium (The dream), a precursor of the science fiction novel, appeared posthumously in 1634. The hero of the piece, a young Icelander named Duracotus, travels to the Moon with the aid of his mother, who is an accomplished witch—an arrangement not unfamiliar to Kepler since his own mother was tried, although not convicted, of witchcraft.
"Just as the eye was made to see colors, and the ear to hear sounds, 4 star hotels england so the human mind was made to understand, not whatever you please, but quantity," wrote Kepler . Kepler based his investigations on careful observations and complex mathematics, but always with a mystical bent, perhaps from his work as an astrologer. As Tycho Brahe's assistant and successor, 4 star hotels england he used Tycho's careful observations to discover the three mathematical laws that describe a planet's orbit, the speed at which it travels, and the time it needs to complete one revolution around the Sun. He proved that Earth and other planets travel in orbits that are ellipses, not circles as had been believed since ancient times. And he showed that the speed of a planet in its orbit is not uniform, but decreases as its distance from the Sun increases, thus overthrowing another long-held belief. Kepler also was a founder of the modern science of optics. He was the first to correctly explain how people 4 star hotels england see -- he noted that the pupil of the eye functions as a diaphragm and that light rays are focused 4 star hotels england on the retina . He also explained why eyeglasses help people see better. After Galileo Galilei sent him one of the first telescopes, he explained 4 star hotels england how the instrument works and improved its design.
( b Weil der Stadt, 27 Dec 1571; d Regensburg, 15 Nov 1630). German scientist and philosopher who wrote on music. Mathematician at the Prague court of Emperor Rudolf II (1601-12), 4 star hotels england he later settled in Linz where his major contribution to music theory, Harmonices mundi , was completed and published in 1619 . In the first two books he traced the origin of the seven 'harmonies' of a string back to archetypes 4 star hotels england inherent in geometry and God. Book 3 contains a treatise on consonance and dissonance, intervals, modes, melody and notation; book 4 is on astrology. In book 5 Kepler described his harmony of the spheres.
Johannes Kepler was born on Dec. 27, 1571, in the Swabian town of Weil. His father, Heinrich Kepler, was a mercenary ; although a Protestant, he enlisted in the troops of the Duke of Alba fighting the Reformed insurgents in the Low Countries. Kepler's grandmother brought him up; for years he was a sickly child. At 13 he was accepted at a theological seminary at Adelberg.
Kepler wanted to become a theologian, and following his graduation from the University of Tübingen, as bachelor of arts in 1591, he enrolled in its theological faculty. But he was also interested in French literature and astronomy. His poor health and proclivity to morbidness singled him out no less than did his precocious advocacy of the doctrine of Copernicus.
It seems that the University of Tübingen gladly presented Kepler for the post of the "mathematician of the province" when request for a candidate came from Graz. He arrived there in April 1594 and set himself to work on one of his duties, the composition of the almanac , in which the main events of the coming year were to be duly predicted. His first almanac was a signal success. The occurrence of two not too unlikely events, an invasion by the Turks and a severe winter, which he had predicted, established his reputation.
Far more important for astronomy was the idea that seized Kepler on July 9, 1595. It appeared to him that the respective radii of the orbits of the planets corresponded to the lengths determined by a specific sequence in which the five regular solids were placed within one another, with a sphere 4 star hotels england separating each solid from the other. The sphere (orbit) of Saturn enveloped a cube which in turn enveloped another sphere, the orbit of Jupiter. This circumscribed a tetrahedron , a sphere (the orbit of Mars), a dodecahedron , a sphere (the orbit of earth), an icosahedron , a sphere (the orbit of Venus), an octahedron , and the smallest sphere (the orbit of Mercury). The idea was the main theme of his Mysterium cosmographicum (1596).
The next year Kepler married Barbara Muehleck, already twice widowed, "under an ominous sky," according 4 star hotels england to Kepler's own horoscope . Of their five children only one boy and one girl reached adulthood . It was with reluctance that Kepler, a convinced Copernican, first sought the job of assistant to Tycho Brahe, the astrologer-mathematician of Rudolph II in Prague. 4 star hotels england He took his new position in 1600. On the death of Tycho the following year, Kepler was appointed his successor.
Kepler's immediate duty was to prepare for publication Tycho's collection of astronomical studies, Astronomiae instauratae progymnasmata (1601-1602). Kepler fell heir to Tycho's 4 star hotels england immensely valuable records. Their outstanding feature lay in the precision by which Tycho surpassed all astronomers before him in observing the position of stars and planets. Kepler tried to utilize Tycho's data in support of his own layout of the circular planetary 4 star hotels england orbits. The facts, that is, Tycho's observations, forced him to make one of the most revolutionary assumptions in the history of astronomy. A difference of 8 minutes of arc between his theory and Tycho's data could be explained only if the orbit of Mars was not circular but elliptical. In a generalized form this meant that the orbits of all planets were elliptical (Kepler's first law). On this basis a proper meaning could be given to another statement 4 star hotels england of his which he had already made in the same context. It is known as Kepler's 4 star hotels england second law, according to which the line joining the planet to the sun sweeps over equal areas in equal times in its elliptical orbit .
Kepler published these laws in his lengthy discussion of the orbit of the planet Mars, the Astronomia nova (1609). The two laws were clearly spelled out also in the book's detailed table of contents. Thus they must have struck the eyes of any careful reader sensitive to an astronomical novelty of such major proportion. Still, Galileo failed to take cognizance of them in his printed works, although 4 star hotels england he could have used them to great advantage to buttress 4 star hotels england his advocacy of the Copernican system.
The relations between Galileo and Kepler were rather strange. Although Galileo remained distinctly unappreciative of Kepler's achievements, the latter wrote a booklet to celebrate Galileo's Starry Messenger immediately upon its publication in 1610. On the other hand, Kepler argued rather vainly 4 star hotels england in his Conversation with the Starry Messenger (