# Khayyáam, Omar (1048–1122)

Omar Khayyáam was a Persian mathematician, astronomer, and poet who, on the accession as sultan of Jalal ad Din Malik Shah, was appointed astronomer royal. Other leading astronomers were also brought to the court observatory in Esfahan and, for 18 years, Khayyáam supervised and produced work of outstanding quality. During this time, Khayyáam led work on compiling astronomical tables and he also contributed to calendar reform in 1079. He measured the length of the year as 365.24219858156 days, which is incredible on two accounts: first that anyone would have the audacity to claim this degree of accuracy (we know now that the length of the year changes in the sixth decimal place within a lifetime) and second that it is astonishingly accurate. For comparison, the length of the year at the end of the twentieth century was 365.242190 days.

Khayyáam's work on algebra was known throughout Europe in the Middle Ages. Among his most important contributions, he discovered a geometrical method to solve cubic equations by intersecting a parabola with a circle, discussed what would become known as Pascal's triangle, and asked if a ratio could be regarded as a number. He is best known, however, as a poet and, in particular, as a result of the popular English translation, in 1859, by Edward Fitzgerald (1809–1883), as the author of the Rubaiyat – a collection 600 short four-line poems. Rosehips from Khayyáam's tomb were germinated at Kew Gardens, London, and planted on Fitzgerald's tomb in St. Michael's Churchyard, Boulge, Suffolk, in 1893; the original plant has died, but its descendents continue to bloom. Omar's full name is Ghiyath al-Din Abu'l-Fath Umar ibn Ibrahim Al-Nisaburi al-Khayyami.