MEDIEVAL LATIN ASTRONOMY
• “MIDDLE AGES” – TIME FROM THE FALL OF ROME IN 476 UNTIL
THE FALL OF CONSTANTINOPLE IN 1453
• EVEN THOUGH ROME RULED AFTER IT CONQUERED GREECE IN THE
2ND CENTURY BC THE LANGUAGE OF SCHOLARSHIP WAS GREEK.
• IN THE EARLY 500’S AD ANICIUS MANILIUS SEVERINUS BOETHIUS
SET OUT TO TRANSLATE ALL OF THE ANCIENT GREEK WORKS INTO
LATIN.
• BEFORE ACCOMPLISHING MUCH HE WAS EXECUTED
• BOETHIUS WORKS CODIFIED WHAT WE NOW CALL THE
QUADRIVIUM:
–
–
–
–
ARITHMETIC (THEORY OF DISCRETE QUANTITIES)
HARMONY (THEORY OF NATURE)
GEOMETRY (THEORY OF CONTINUOUS QUANTITIES)
ASTRONOMY
MEDIEVAL LATIN ASTRONOMY
• MARTIANUS CAPELLA OF CARTHAGE WROTE
AN ALLEGORY OF HEAVENLY MARRIAGE IN
THE 5TH CENTURY AD
• IN IT HE DESCRIBED A SYSTEM SIMILAR TO
THAT OF HERACLIDES (AND FORESHADOWING
TYCHO’S SYSTEM) IN WHICH MERCURY AND
VENUS CIRCLED THE SUN AND THE SUN, IN
TURN, CIRCLED THE EARTH.
MEDIEVAL LATIN ASTRONOMY
• AMBROSIUS THEODOSIUS MACROBIUS (5TH CENTURY
AD) ENUNCIATED A COSMOLOGY DRAWN FROM PLATO
AND THE PYTHAGOREANS:
– SPHERICAL EARTH
• CENTER OF THE UNIVERSE
• ENCIRCLED BY SEVEN PLANETARY SPHERES
– THEY WERE ENCIRCLED BY THE STARRY SPHERE WHICH ROTATED DAILY
FROM EAST TO WEST DRAGGING THE PLANETARY SPHERES ALONG.
• EACH PLANETARY SPHERE HAD ITS OWN MOTION
– THE EARTH WAS DIVIDED BY OCEANS INTO FOUR
QUARTERS
– THE SIZE OF THE EARTH WAS THAT DETERMINED BY
ERATOSTHENES
MEDIEVAL LATIN ASTRONOMY
• A RELIABLE CALENDAR WAS NEEDED IN CHRISTENDOM, AS IN
ISLAM, TO SET FESTIVAL TIMES
• EASTER WAS DETERMINED TO OCCUR ON:
– FIRST SUNDAY FOLLOWING THE
– PASCHAL (DERIVED FROM THE WORD “PASSOVER”) FULL MOON
(ACTUALLY 14TH DAY OF THE MOON) FOLLOWING - (DETERMINED
USING METONIC CYCLE) THE
– VERNAL EQUINOX
• TIME OF DAY WAS IMPORTANT TO CERTAIN PRAYER TIMES AND
VESPERS
• DETERMINED BY:
– LOCATION OF THE STARS
– WATER CLOCKS
– RHYTHMIC CHANTING
MEDIEVAL LATIN ASTRONOMY
• ASTRONOMY REVIVED IN THE
WEST WHEN CONTACT WITH
ISLAMIC ASTRONOMERS WAS
MADE THROUGH SPAIN IN THE
10TH CENTURY.
• GERBERT OF AURILLAC (LATER
POPE SYLVESTER II) BROUGHT
KNOWLEDGE OF THE ASTROLABE
FROM SPAIN TO ROME IN 1025
• ASTROLOGY BECAME IMPORTANT
DURING THE BLACK PLAGUE
(BLACK DEATH) OF 1348-1350
• ARISTOTLE’S ANALOGY OF THE
HEAVENS AND THE HUMAN BODY
(SEE PANEL TO THE RIGHT)
PROMOTED MEASUREMENTS OF
THE POSITIONS OF THE PLANETS.
MEDIEVAL LATIN ASTRONOMY
• WHEN TOLEDO FELL IN 1085 MANY OF THE EARLIER ISLAMIC
WORKS BECAME AVAILABLE TO THOSE IN THE WEST
• GERARD OF CREMONA WENT TO SPAIN AND TRANSLATED MORE
THAT 70 VOLUMES INTO LATIN
• THEY COULD NOW PREDICT THE POSITIONS OF THE PLANETS
• HOWEVER, THEORIES OF THE MOTIONS SET DOWN IN THE
ALMAGEST REMAINED A MYSTERY TO THEM.
• PARIS BECAME A CENTER OF LEARNING IN THE 13TH CENTURY.
• THE STUDY OF ARTS AND SCIENCE WAS ELEVATED TO THAT OF
THEOLOGY.
• THOMAS AQUINAS ADDRESSED THE PROBLEMS THAT AROSE BY
INTRODUCING “PAGAN” IDEAS INTO THEIR CURRICULUM. IN FACT
ARISTOTILEAN IDEAS WERE ELEVATED TO THAT OF REVELATION.
• THE ALMAGEST REMAINED TOO DIFFICULT FOR MOST STUDENTS.
MEDIEVAL LATIN ASTRONOMY
• PARISIAN SCHOLARS ACKNOWLEDGED THAT PRECESSION
OCCURRED
• THEY ALSO (ERRONEOUSLY) THOUGHT THAT THERE WAS A
VARIATION IN PRECESSION WHICH THEY LABELED “TREPIDATION”.
• THEY WERE PARTICULARLY INTERESTED IN CORRELATING THE
ARISTOTILEAN PARTS OF THE UNIVERSE WITH THOSE REFERRED TO
IN THE BOOK OF GENESIS.
– THE FIRST SEVEN SPHERES WERE THOSE OF THE PLANETS
– THE EIGHTH SPHERE WAS THAT OF THE “FIRMAMENT”, WHERE THE
FIXED STARS RESIDED AND IN WHICH PRECESSION OCCURRED.
– GENESIS’ “WATERS ABOVE THE FIRMAMENT” REFERRED TO THE
NINTH (OR NINTH AND TENTH) SPHERE. IT WAS CRYSTALLINE AND
WAS WHERE “TREPIDATION” WAS THOUGHT TO OCCUR.
– THE ELEVENTH SPHERE WAS MOTIONLESS. IT REFERRED TO HEAVEN,
THE ABODE OF GOD.
MEDIEVAL LATIN ASTRONOMY
• IN ABOUT 1230 JOHN OF HOLYWOOD
(SACROBOSCO) WROTE THREE NEW TEXTBOOKS
RELATED TO TIME KEEPING AND ASTRONOMY.
• HIS SPHERE WAS ADOPTED AS A TEXT BUT WAS
MOSTLY UNSATISFACTORY IN ITS TREATMENTS
• AN ANONYMOUS TEXT THEORY OF THE PLANETS
REPLACED IT.
• IT WAS, IN TURN, REPLACED BY BETTER WORKS.
• THE LEVEL OF MEDIEVAL ASTRONOMY
PROGRESSED SLOWLY.
MEDIEVAL LATIN ASTRONOMY
• IN THE 13TH CENTURY KING ALFONSO X OF
CASTILE PUBLISHED A NEW SET OF TABLES OF
PLANETARY MOTION
• CALLED THE “ALPHONSINE TABLES”
• THEY REPLACED THE OLD “TOLEDAN TABLES”
INHERITED FROM THE ISLAMIC ASTRONOMERS
• NEW INSTRUMENTS LIKE THE ASTROLABE
APPEARED AND MASSIVE OLD OBSERVATORIES
WERE NO LONGER NECESSARY.
MEDIEVAL LATIN ASTRONOMY
THE OLD QUADRANT, USED TO
MEASURE ALTITUDES
THE NEW QUADRANT/ASTROLABE,
INTRODUCED BY “PROFATIUS THE JEW”,
JACOB BEN MAHIR
MEDIEVAL LATIN ASTRONOMY
• THE CROSS STAFF
• INTRODUCED BY LEVI BEN
GERSON
• MEASURED ANGLE
BETWEEN TWO OBJECTS
• USED TO DETERMINE A
MARINER’S LATITUDE
• MEASURED ALTITUDE OF
SUN AT NOON
• POLARIS NOT ADEQUATE IN
1500 AS IT WAS 3 DEGREES
FROM THE POLE THEN
MEDIEVAL LATIN ASTRONOMY
A NOCTURNAL – USED TO
DETERMINE THE TIME AT NIGHT
A NOCTURLABE – USED TO
DETERMINE TIME AT NIGHT AND TO
TIME THE TIDES
MEDIEVAL LATIN ASTRONOMY
TIME KEEPING
ASTRONOMICAL CLOCK OF RICHARD
OF WALLINGFORD, ABBOT OF ST
ALBANS, EARLY 14TH CENTURY
ASTRARIUM – INVENTED BY
GIOVANI DE’ DONDI IN 1364 , LIVED
IN PADUA
PREVIOUSLY HELD CONCEPTS ARE CALLED INTO
QUESTION
• MOST BELIEVED THAT THE CONCEPT OF THE
EQUANT WAS INCORRECT. PLANETARY MOTION
HAD TO BE UNIFORM
• ARISTOTLE IDEAS ARE QUESTIONED
– COULD THE EARTH ACTUALLY BE ROTATING?
– HIS LAWS OF INERTIA WERE CLEARLY WRONG
• FOR EXAMPLE, AN ARROW SHOT INTO THE AIR CONTINUED
TO RECEDE FROM THE EARTH AFTER IT HAD LEFT THE BOW.
ARISTOTILEAN PRECEPTS SUGGESTED THAT, SINCE THE
ARROW WAS “EARTH” IT SHOULD IMMEDIATELY SEEK THE
EARTH
• ARISTOTLE SUGGESTED THAT AIR SUPPLIED THE FORCE THE
CAUSED THE ARROW TO CONTINUE TO RISE
MEDIEVAL LATIN ASTRONOMY
• JEAN BURIDAN (c. 1295 – c. 1358) AND NICOLE
ORESME (c. 1320 – C. 1382) SUGGESTED THAT
AIR WAS NOT THE FORCE BUT “IMPETUS” (WHAT
WE WOULD CALL MOMENTUM) PROVIDED BY
THE BOW SUPPLIED THE FORCE.
• BURIDAN ARGUED THAT, IF THE EARTH WERE
ROTATING, IT WOULD MOVE THE ARCHER AS
WELL AS THE ARROW AND THAT ONE COULD
NOT TELL FROM SUCH AN EXPERIMENT
WHETHER THE EARTH ROTATED
• BURIDAN BELIEVED THAT THE EARTH WAS FIXED
MEDIEVAL LATIN ASTRONOMY
• BURIDAN ALSO DISAGREED WITH THE
ARISTITOLEAN IDEA THAT “GOD” OR “GODS”
SUPPLIED THE FORCE(S) THAT KEPT THE
CELESTIAL SPHERE TURNING
• HE SAID THAT, IN THE ABSENCE OF FRICTION,
NO FORCE WOULD BE NEEDED – IMPETUS
WOULD KEEP IT TURNING
• THIS LOOKS VERY MUCH LIKE NEWTON’S
“FIRST LAW”
MEDIEVAL LATIN ASTRONOMY
THE RENAISSANCE APPROACHES
•
•
•
•
GUTENBURG DEVELOPS THE PRINTING PRESS IN 1450
THE GUTENBURG BIBLE IS PUBLISHED IN 1455
WITH PRINTING SCRIBES’ ERRORS CEASED
JOHANNES BESSARION (c. 1395 – c. 1472), GEORG PEURBACH
(1422–1461) AND JOHANNES MULLER OF KONIGSBERG (1436-1476)
COLLABORATED TO PUBLISH A NUMBER OF ASTRONOMICAL
TREATISES.
– PEURBACH WROTE NEW THEORIES OF THE PLANETS
– MULLER OVERSAW IT’S PRINTING AFTER PEURBACH’S DEATH
– BESSARION SET OUT TO PRINT AN ABRIDGED VERSION OF THE
ALMAGEST – HE SUCCEDED IN PRINTING ONLY SIX VOLUMES
– MULLER OVERSAW IT’S PRINTING AFTER BESSARION’S DEATH
• BERNARD WALTHER (1430-1504), A MERCHANT IN NUREMBERG,
BUILT ON MULLER’S WORK AND PRODUCED A NUMBER OF
OBSERVATIONS LATER USED BY COPERNICUS, TYCHO AND KEPLER