Persian astronomy orIranian astronomy refers to theastronomy inancient Persian history.^[1]

AncientPersians celebrated thevernal equinox,summer solstice,autumnal equinox, andwinter solstice through a variety of different festivals and traditions.^[2]

Nowruz is the day of thevernal equinox and the moment theSun crosses thecelestial equator has been calculated for years. Nowruz was an important day during theAchaemenid period and continued in importance through theSasanian dynasty.^[3][4]

Tirgan is an ancient Iranian festival celebrating thesummer solstice.^[5]

Mehregan is an ancientZoroastrian and Persian festival celebrating theautumnal equinox since at least the4th century BC.^[6]

Yaldā Night is an ancient Iranian festival celebrating thewinter solstice of theNorthern Hemisphere.^[2][7][8]

Some oldPersian names in astronomy have barely survived; the names of the fourRoyal stars that were used by the Persians foralmanacs areAldebaran,Regulus,Antares andFomalhaut, and are thought by scientists to equate to the modern-daystar systems ofAlcyone, Regulus,Albireo, andBungula (Alpha Centauri) for almanacs.^[9]

Tablet inscriptions set forth observations ofJupiter from the 43rd year of the reign ofArtaxerxes II to the thirteenth year ofAlexander the Great.^[9] The positions of the planets throughout the year were determined using astrological charts.^[9]

After theMuslim conquest of Persia, much of Persian astronomy andastrology became intertwined with theastronomy in the medieval Islamic world, paving way for theIslamic Golden Age. Scientists translated studies inSanskrit,Middle Persian, andGreek intoArabic, where the Indian Sanskrit and Persian Pahlavi (Middle Persian) sources taught medieval astronomers methods for calculating the position of heavenly bodies, and for creating tables recording the movement of the sun, themoon, and the five known planets.^[10]

The first major Muslim work of astronomy wasZij al-Sindhind by Persian mathematicianal-Khwarizmi in 830. The work contains tables for the movements of the Sun, the moon and the five planets known at the time, and is significant as it introducedPtolemaic concepts into Islamic sciences. This work also marks the turning point in Islamic astronomy. Hitherto, Muslim astronomers had adopted a primarily research approach to the field, translating works of others and learning already discovered knowledge. Al-Khwarizmi's work marked the beginning of nontraditional methods of study and calculations.^[11]