JOHANNES KEPLER1571-1630

• BORN IN WEIL DER STADT NEAR PRESENT DAY STUTTGART

• HE WAS BORN PREMATURELY AND WAS PHYSICALLY WEAK.

• HIS FAMILY WAS POOR– HIS FATHER WAS A MERCENARY

WHO IS BELIEVED TO HAVE DIED IN THE EIGHTY YEARS WAR IN THE NETHERLANDS

– HIS MOTHER WAS A HEALER/HERBALIST WHO WAS LATER TRIED FOR WITCHCRAFT

JOHANNES KEPLER• HE BECAME INTRIGUED BY ASTRONOMY AT AN EARLY AGE WHEN HE

OBSERVED THE GREAT COMET OF 1577 (IT WAS ALSO OBSERVED BY TYCHO) AND THE TOTAL LUNAR ECLIPSE OF 1580

• AT AGE 18 HE ATTENDED THE UNIVERSITY OF TUBINGEN WHERE HE STUDIED PHILOSOPHY AND THEOLOGY

• AT AGE 19 HE BECAME CHANCELLOR AT THE UNIVERSITY OF TUBINGEN IN 1590 (?)

• HE BECAME AN ACCOMPLISHED MATHEMATICIAN AND ALSO PRACTICED ASTROLOGY.

• HE BELIEVED IN COOPERNICUS’ HELIOCENTRISM AND DEFENDED IT IN DEBATES.

• AT AGE 23 HE JOINED THE MATHEMATICS AND ASTRONOMY FACULTY AT THE UNIVERSITY OF GRAZ, AUSTRIA.

JOHANNES KEPLER

• HE, LIKE PYTHAGORAS MANY YEARS EARLIER, BELIEVED THAT THERE WAS A HARMONY IN NATURE THAT COULD BE EXPRESSED IN SIMPLE MATHEMATICAL RATIOS AND COULD, IN FACT, BE DETECTED AS MUSIC.

• HIS MATHEMATICAL SPECIALTY WAS GEOMETRY.

JOHANNES KEPLER• HE WONDERED WHY THERE WERE SIX PLANETS, NOT FIVE, REASONING THAT GOD

MUST HAVE HAD A REASON.• HE WAS INSPIRED BY THE 1595 CONJUNCTION OF JUPITER AND SATURN TO

EUCLID’S POLYGONS.• HE THEN REALIZED THAT THERE WERE FIVE REGULAR SOLIDS (PYRAMID (4), CUBE

(6), OCTAHEDRON (8), DODECAHEDRON (12) AND ICOSAHEDRON (20)).• HE ORGANIZED THEM: OCTAHEDRON, ICOSAHEDRON, DODEDAHEDRON,

TETRAHEDRON AND CUBE, RESPECTIVELY STARTING WITH MERCURY AND WORKING OUT TO SATURN.

• IF THEY WERE SUCCESSIVELY INSCRIBED AND CIRCUMSCRIBED BY SPHERES THESE SPHERES COULD REPRESENT THE ORBITS OF SIX PLANETS.

• HE MAINTAINED THAT THE PLANETS WOULD STOP UNLESS THERE WAS A FORCE CAUSING THEM TO MOVE. THE SUN WAS THAT SOURCE AND THE PLANETS NEARER THE SUN WOULD MOVE FASTER AS THEY WERE CLOSER.

• HE ARGUED THAT, AS PROPOSED BY WILLIAM GILBERT (1544-1603), AN ENGLISHMAN, MAGNETISM WAS THE SOURCE MECHANISM.

• HE REASONED THAT, SINCE THE SUN WAS OBVIOUSLY BIGGER THAN THE EARTH, IT OUGHT TO BE AT THE CENTER OF THE SOLAR SYSTEM.

KEPLER’S NESTED SPHERESOUTER PORTION INNER PORTION

KEPLER MEETS TYCHO• HIS FIRST MAJOR ASTRONOMICAL WORK, MYSTERIUM COSMOGRAPHICUM

(THE COSMIC MYSTERY), PUBLISHED IN 1595, DESCRIBED HIS INSCRIBED POLYHEDRONS.

• HE COMMUNICATED WITH TYCHO AND WITH REIMARUS URSUS (A COPERNICAN AND BITTER RIVAL OF TYCHO), IMPERIAL MATHEMATICIAN TO RUDOLPH II, SOLICITING THEIR OPINIONS ABOUT “COSMIC MYSTERY”. (TYCHO REPLACED URSUS A FEW YEARS LATER.)

• HE ALSO STUDIED THE “HARMONY” OF THE RELATIONSHIPS AMONG MUSIC, MATH AND THE PHYSICAL WORLD, WITH SPECIAL EMPHASIS ON ASTROLOGY.

• HOWEVER, TO CHECK ALL OF HIS THEORIES, HE BADLY NEEDED TYCHO’S DATA.• TYCHO WAS NOW IN PRAGUE. KEPLER NEEDED TYCHO’S SUPPORT, BOTH

FINANCIAL AND PROFESSIONAL. AND, KEPLER WAS IN TROUBLE WITH THE CHURCH AS HE WAS BEING PRESSURED INTO CONVERTING TO CATHOLOCISM.

• KEPLER TRAVELED TO PRAGUE TO MEET TYCHO.

HOW DID KEPLER GET HIS HANDS ON TYCHO’S DATA?

• TYCHO KNEW THAT KEPLER WANTED ACCESS TO HIS DATA BUT REFUSED TO LET HIM COPY THEM.

• KEPLER ANGRILY LEFT PRAGUE TWO MONTHS LATER BUT RETURNED AND RECONCILED TWO MONTHS AFTER THAT.

• KEPLER MOVED TO PRAGUE PERMANENTLY AFTER HAVING BEEN BANNED FROM GRAZ FOR REFUSING TO CONVERT TO CATHOLICISM.

• IN 1601 TYCHO TASKED KEPLER WITH WRITING A TRACT AGAINST URSUS, TYCHO’S NOW DECEASED FOE.

• AFTER TYCHO’S DEATH KEPLER SNATCHED HIS DATA.• EVENTUALLY HIS HEIRS REGAINED THE VALUABLE DATA BUT NOT

BEFORE KEPLER HAD COPIED ALL THAT HE WANTED.

JOHANNES KEPLER• AFTER TYCHO’S DEATH KEPLER REPLACED HIM AS THE IMPERIAL MATHEMATICIAN.• MARS WAS OF SPECIAL INTEREST

– IT (OTHER THAN MERCURY) HAS THE MOST ECCENTRIC ORBIT OF ANY PLANET– TYCHO HAD MADE COPIUS OBSERVATIONS OF IT

• USING ABOUT HALF OF TYCHO’S DATA HE GENERATED A SYSTEM PREDICTING MARS’ ORBIT AS SEEN FROM THE EARTH WHEN MARS WAS AT OPPOSITION

• HE THEN USED THE OTHER HALF OF TYCHO’S DATA TO REVERSE THE PROCESS TO PREDICT THE POSITION OF THE EARTH AS SEEN FROM MARS.

• HE HAD ADOPTED THE IDEA THAT PLANETARY ORBITS WERE ELLIPTICAL. REMEMBER, APPOLONIUS HAD DEFINED THE SHAPE OF AN ELLIPSE ABOUT 1500 YEARS EARLIER.

• TYCHO’S DATA FORCED HIM TO ABANDON THE IDEA THAT THE SUN WAS AT THE CENTER OF THE ELLIPSE AND PUT IT A FOCUS. HIS “SUN-CENTERED ELLIPSE” THEORY DISAGREED WITH TYCHO’S DATA BY ABOUT 8 ARC MINUTES. HE FELT TYCHO’S DATA WERE MORE ACCURATE THAT THAT AND ABANDONED HIS THEORY.

KEPLERS’ SUPERNOVA (1604)SN-1604

• THOUGHT BY ASTROLOGERS TO BE THE ANNOUNCEMENT OF A NEW ERA. THEY HAD THOUGHT THERE WAS AN 800 YEAR PERIOD IN THE STARS. 1600 YEARS EARLIER WAS THE TIME OF CHRIST. 800 YEARS AFTER THAT WAS THE BEGINNING OF THE REIGN OF CHARLEMAIGN.

• HE OBSERVED, AS DID TYCHO, THAT SUCH OBJECTS DO NOT HAVE ANY MEASURABLE PARALLAX THEREFORE THEY ARE OUTSIDE THE EARTH’S ATMOSPHERE.

KEPLERS’ SUPERNOVA (1604)SN-1604

• SUPERNOVA IS LOCATED AT THE FOOT OF OPHIUCHUS (THE SNAKE HOLDER) ONE OF THE CONSTELLATIONS NAMED BY PTOLEMY

JOHANNES KEPLER

• IN 1610 GALILEO OBSERVED THE MOONS OF JUPITER AND SOUGHT KEPLER’S THOUGHTS

• KEPLER RESPONDED ENTHUSIASTICALLY AND PROCEEDED TO PUBLISH ANALYSES OF BOTH GALILEO’S AND HIS OWN TELESCOPES

• IT APPEARS BOTH THOUGHT THAT JUPITER WAS SOMETHING VERY SPECIAL, PROVING THAT THE EARTH WAS NOT THE CENTER OF ALL REVOLUTIONS

GALILEAN TELESCOPEVIRTUAL ERECT IMAGE – CURRENT DAY OPERA GLASSES

KEPLER’S TELESCOPEINVERTED IMAGE

KEPLER’S HARMONICES MUNDI, (HARMONY OF THE WORLDS)

• PUBLISHED IN 1619• MOST OF IT DEALT WITH

ASTROLOGY• HE ATTEMPTED TO

CORRELATE MUSICAL TONES WITH PLANETARY SPEED.

• NOTE: BACH’S WELL TEMPERED CLAVIER WAS STILL A CENTURY AWAY.

• WE GET HIS THIRD LAW FROM IT.

KEPLER’S Epitome astronomia Copernicanae (Epitome of Copernican Astronomy)

• PUBLISHED IN FOUR VOLUMES FROM 1615-1621

• HE WROTE MUCH OF IT DURING HIS MOTHER’S WITCHCRAFT TRIAL

• HIS MOST INFLUENTIAL WORK• CONTAINED ALL OF HIS THREE LAWS

KEPLER’S LAWS

• PLANETS MOVE IN ELLIPTICAL ORBITS, THE SUN AT A FOCUS.

• THE RADIUS VECTOR OF A PLANETARY ORBIT SWEEPS OUT EQUAL AREAS IN EQUAL TIMES.

• P2 = a3, WHERE P IS THE SIDEREAL PERIOD OF A PLANET IN EARTH YEARS AND A IS THE SEMI-MAJOR AXIS IN ASTRONOMICAL UNITS.

JOHANNES KEPLER

• IN 1627, 26 YEARS AFTER THEY HAD BEEN COMMISSIONED (HE HAD TROUBLE WITH TYCHO’S HEIRS AND THE PUBLISHING REQUIREMENTS OF THE EMPEROR), HE FINISHED THE RUDOLPHINE TABLES.

• IN 1631, ONE YEAR AFTER HIS DEATH, PIERRE GASSENDI, A FRENCH ASTRONOMER, MADE THE FIRST OBSERVATION OF MERCURY’S SOLAR TRANSIT.

• KEPLER’S TABLES WERE ACCURATE TO 1/6TH OF A DEGREE, THIRTY TIMES MORE ACCURATE THAN THE OLD COPERNICAN (PRUTENIC) TABLES.

JOHANNES KEPLER• IN 1625 HE RAN AFOUL OF THE CATHOLIC CHURCH ONCE AGAIN• AGENTS OF THE CATHOLIC “COUNTER-REFORMATION” SEALED HIS LIBRARY.• HE MOVED TO ULM IN 1626 WHERE HE PRINTED HIS TABLES AT HIS OWN

EXPENSE.• MILITARY TENSION EASED IN 1628 AND, EVEN THOUGH THE EMPEROR

(FERDINAND) WAS A STAUNCH CATHOLIC, HE WAS NAMED AN OFFICIAL ADVISOR TO GENERAL WALLENSTEIN, FERDINAND’S HIGHEST RANKING GENERAL.

• HIS PRIMARY DUTIES TO THE GENERAL WERE TO SUPPLY SUPERIOR DATA TO THE GENERAL’S ASTROLOGERS.

• AFTER A BRIEF ILLNESS HE DIED IN REGENSBURG IN 1630.• HIS GRAVE SITE WAS DESTROYED WHEN THE SWEDISH ARMY DESTROYED

THE CHURCH YARD AND ITS LOCATION IS UNKNOWN.