Major impetus came from religious observances: Major impetus came from religious observances

Major impetus came from religious observances:

• Major impetus came from religious observances:

• Presented an assortment of problems in mathematical
• astronomy.

• Religious customs presenting problems in spherical astronomy:

• Crescent Moon: start of Islamic month
• Direction of Qibla: praying toward Mecca
• Proper time for the five daily prayers.

Baghdad

• Baghdad

• Started from the reign of Caliph al-Mansur (754-775)
• Under Harun ar-Rashid and al-Ma’mun, the school of Baghdad produced its most important works.
• Old theories were revised, Ptolemy’s errors were rectified, and the astronomical tables of the Greeks corrected.
• Most Important Astronomical Works:
• Detailed study of the exact duration of the solar year (al-Battani)
• Prediction of solar and lunar eclipses (al-Battani)
• Theory of the lunar crescent visibility.
• Al-Battani’s Zij, considered as the most important astronomical works between the time of Ptolemy and that of Copernicus.

Cairo:

• Cairo:

• Founded by the illustrated Ali Ibn Yunus, inventor of the pendulum, and the solar quadrant.
• Most Important Astronomical Works:
• “Al-Hakimi Zij”, astronomical tables edited by Ibn Yunus, used in Cairo into the 19th century.
• More than 100 solar observations and planetary conjunctions are reported in the Hakimi Zij.
• Optical treatises of Hassan Ibn al-Haytham, which served as the basis for the works of Roger Bacon and Kepler.

Many cultures around the world observed the sky and marked important alignments

• Many cultures around the world observed the sky and marked important alignments

• But, having no written language, left no detailed records of their astronomical beliefs.

• Greek astronomy, derived in part from Babylon and Egypt, is better known because written documents have survived.

• Greek astronomers believed firmly in two principles:

• Geocentric universe: Earth center of the whole universe
• Perfect heavens: Heavens must be made of spheres in uniform motion

• Ptolemy Universe: Added epicycles to account for the retrograde motion

Muslim astronomers:

• Muslim astronomers:
• Revised old theories.
• Rectified Ptolemy’s errors.
• Corrected the astronomical tables of the Greeks.

• School of Baghdad:

• Best work: Al-Battani’s Zij, considered as the most important astronomical works between the time of Ptolemy and that of Copernicus.

• School of Cairo:

• Best work: “Al-Hakimi Zij”, astronomical tables edited by Ibn Yunus, used in Cairo into the 19th century.

Ptolemy's model of the universe

• Ptolemy's model of the universe

• a. was heliocentric.

• b. included elliptical orbits.

• c. contained epicycles.

• d. all of the above

• 2. The purpose of using epicycles to explain the motion of the planets

• in the night sky was to account for

• a. prograde motion.

• b. Mercury and Venus’ limited angular distance from the Sun.

• c. retrograde motion.

• d. non-uniform speed of the planets in their orbits.

Why did the Greeks believed firmly in the geocentric system?

• Why did the Greeks believed firmly in the geocentric system?

Maragha:

• Maragha:

• Started with Nasir al-Din al-Tusi by the construction of the Maragha observatory in 1259.
• Responsible for the revival of Islamic science in all fields.
• Astronomical activities influenced the observatories of Samarqand and Istanbul, and also those in the West.

• Most Important Astronomical Works:

• Compilation of the “Ilkhani Zij” displaying the results of 12 years of observations at the Maragha observatory.

Samarqand:

• Samarqand:

• Started with the foundation of a “Madrasa” by Ulugh Begh in 1420.
• Lecturers included the most famous Muslim mathematicians and astronomers (Kadi Zada and al-Kashi) brought under one roof.
• Thousands of students were lectured and were assisted by hundred of scientists.
• An Observatory was built to fulfill the task of completing the educational needs of the students in astronomy.

• Most Important Astronomical Works:

• Compilation of Ulugh Begh’s Zij displaying the results of 20 years of observations at the Samarqand observatory.
• Yearly movements of Saturn, Jupiter, Mars, and Venus were known to within the limits of two to five seconds of those of modern times.

Why would one say the Copernican hypothesis was correct but the model inaccurate?

• Why would one say the Copernican hypothesis was correct but the model inaccurate?

Greek astronomy was based on a geocentric universe.

• Greek astronomy was based on a geocentric universe.

• Islamic astronomy revised the Greek astronomy and introduced the concept of observatory.

• Renaissance astronomers refuted the geocentric model, and supported the heliocentric model.

• Kepler’s three empirical laws explain the motion of planets in the heliocentric model.