Persian astronomy or Iranian astronomy refers to the

astronomy Astronomy is a natural science that studies celestial objects and the phenomena that occur in the cosmos. It uses mathematics, physics, and chemistry in order to explain their origin and their overall evolution. Objects of interest includ ...

in ancient Persian history.

Pre-Islamic history

Ancient

Persians Persians ( ), or the Persian people (), are an Iranian ethnic group from West Asia that came from an earlier group called the Proto-Iranians, which likely split from the Indo-Iranians in 1800 BCE from either Afghanistan or Central Asia. They ...

celebrated the vernal equinox,

summer solstice The summer solstice or estival solstice occurs when one of Earth's poles has its maximum tilt toward the Sun. It happens twice yearly, once in each hemisphere ( Northern and Southern). The summer solstice is the day with the longest peri ...

, autumnal equinox, and

winter solstice The winter solstice, or hibernal solstice, occurs when either of Earth's geographical pole, poles reaches its maximum axial tilt, tilt away from the Sun. This happens twice yearly, once in each hemisphere (Northern Hemisphere, Northern and So ...

through a variety of different festivals and traditions.

Vernal equinox

Nowruz Nowruz (, , () , () , () , () , Kurdish language, Kurdish: () , () , () , () , , , , () , , ) is the Iranian or Persian New Year. Historically, it has been observed by Iranian peoples, but is now celebrated by many ...

is the day of the vernal equinox and the moment the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

crosses the

celestial equator The celestial equator is the great circle of the imaginary celestial sphere on the same plane as the equator of Earth. By extension, it is also a plane of reference in the equatorial coordinate system. Due to Earth's axial tilt, the celestial ...

has been calculated for years. Nowruz was an important day during the Achaemenid period and continued in importance through the Sasanian dynasty.

Summer solstice

Tirgan is an ancient Iranian festival celebrating the

Autumnal equinox

Mehregan Mehregan () or Jashn-e Mehr ( ''Mithra Festival'') is a Zoroastrianism, Zoroastrian and Iranian peoples, Iranian festival celebrated to honor the yazata Mithra (), which is responsible for friendship, affection and love. Name "Mehregan" is ...

is an ancient

Zoroastrian Zoroastrianism ( ), also called Mazdayasnā () or Beh-dīn (), is an Iranian religion centred on the Avesta and the teachings of Zarathushtra Spitama, who is more commonly referred to by the Greek translation, Zoroaster ( ). Among the wo ...

and Persian festival celebrating the autumnal equinox since at least the 4th century BC.

Winter solstice

Yaldā Night is an ancient Iranian festival celebrating the

of the

Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...

Star systems

Some old Persian names in astronomy have barely survived; the names of the four Royal stars that were used by the Persians for

almanac An almanac (also spelled almanack and almanach) is a regularly published listing of a set of current information about one or multiple subjects. It includes information like weather forecasting, weather forecasts, farmers' sowing, planting dates ...

s are

Aldebaran Aldebaran () is a star in the zodiac constellation of Taurus. It has the Bayer designation α Tauri, which is Latinized to Alpha Tauri and abbreviated Alpha Tau or α Tau. Aldebaran varies in brightness from an apparent vis ...

Regulus Regulus is the brightest object in the constellation Leo (constellation), Leo and one of the List of brightest stars, brightest stars in the night sky. It has the Bayer designation designated α Leonis, which is Latinisation of names, ...

Antares Antares is the brightest star in the constellation of Scorpius. It has the Bayer designation α Scorpii, which is Latinisation of names, Latinised to Alpha Scorpii. Often referred to as "the heart of the scorpion", Antares is flanked by ...

and Fomalhaut, and are thought by scientists to equate to the modern-day

star systems A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. It may sometimes be used to refer to a single star. A large group of stars bound by gravitation is generally called a ''st ...

of Alcyone, Regulus, Albireo, and Bungula (Alpha Centauri) for almanacs.

Planets

Tablet inscriptions set forth observations of

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...

from the 43rd year of the reign of

Artaxerxes II Arses (; 445 – 359/8 BC), known by his regnal name Artaxerxes II ( ; ), was King of Kings of the Achaemenid Empire from 405/4 BC to 358 BC. He was the son and successor of Darius II () and his mother was Parysatis. Soon after his accession, Ar ...

to the thirteenth year of

Alexander the Great Alexander III of Macedon (; 20/21 July 356 BC – 10/11 June 323 BC), most commonly known as Alexander the Great, was a king of the Ancient Greece, ancient Greek kingdom of Macedonia (ancient kingdom), Macedon. He succeeded his father Philip ...

. The positions of the planets throughout the year were determined using astrological charts.

After Muslim conquests

After the

Muslim conquest of Persia As part of the early Muslim conquests, which were initiated by Muhammad in 622, the Rashidun Caliphate conquered the Sasanian Empire between 632 and 654. This event led to the decline of Zoroastrianism, which had been the official religion of ...

, much of Persian astronomy and

astrology Astrology is a range of Divination, divinatory practices, recognized as pseudoscientific since the 18th century, that propose that information about human affairs and terrestrial events may be discerned by studying the apparent positions ...

became intertwined with the

astronomy in the medieval Islamic world Medieval Islamic astronomy comprises the astronomical developments made in the Islamic world, particularly during the Islamic Golden Age (9th–13th centuries), and mostly written in the Arabic language. These developments mostly took place in th ...

, paving way for the

Islamic Golden Age The Islamic Golden Age was a period of scientific, economic, and cultural flourishing in the history of Islam, traditionally dated from the 8th century to the 13th century. This period is traditionally understood to have begun during the reign o ...

. Scientists translated studies in

Sanskrit Sanskrit (; stem form ; nominal singular , ,) is a classical language belonging to the Indo-Aryan languages, Indo-Aryan branch of the Indo-European languages. It arose in northwest South Asia after its predecessor languages had Trans-cultural ...

Middle Persian Middle Persian, also known by its endonym Pārsīk or Pārsīg ( Inscriptional Pahlavi script: , Manichaean script: , Avestan script: ) in its later form, is a Western Middle Iranian language which became the literary language of the Sasania ...

, and

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

into

Arabic Arabic (, , or , ) is a Central Semitic languages, Central Semitic language of the Afroasiatic languages, Afroasiatic language family spoken primarily in the Arab world. The International Organization for Standardization (ISO) assigns lang ...

, 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, the

moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

, and the five known planets. The first major Muslim work of astronomy was ''Zij al-Sindhind'' by Persian mathematician

al-Khwarizmi Muhammad ibn Musa al-Khwarizmi , or simply al-Khwarizmi, was a mathematician active during the Islamic Golden Age, who produced Arabic-language works in mathematics, astronomy, and geography. Around 820, he worked at the House of Wisdom in B ...

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 introduced Ptolemaic 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.Dallal (1999), pg. 163

References

{{Astronomy navbox Astronomy in Iran Persian culture Culture of Iran