Omar Khayyam's 971st birthday: Why this Persian mathematician was special?

Google is celebrating Omar Khayyam's 971st by a special, creative doodle.

Omar Khayyam's 971st birthday is being celebrated by Google on May 18 with a special, creative doodle. This is one of those rare times that Google has repeated a doodle.

In 2012 as well, Omar's 964th birthday was celebrated by Google with a special doodle which was very well received by users.

Omar Khayyam was a Persian mathematician, but he was also a well-known astronomer, and poet. He was born in Nishapur, in northeastern Iran, and spent most of his life near the court of the Karakhanid and Seljuq rulers in the period which witnessed the First Crusade.

As a mathematician, Omar Khayyam is very well-known for his work on the classification and solution of cubic equations, where he provided geometric solutions by the intersection of conics. 

Omar Khayyam was first to give a general method for solving cubic equations. Although he didn't consider negative roots, his methods are sufficient to find geometrically all real (positive or negative) roots of cubic equations.