He reckoned the value as 1 per century, a value that was not improved upon until about 1000 years later, by Islamic astronomers.

From about the 10th century, they were made more sophisticated as navigational aids by Islamic astronomers.

"We're hoping to get a speaker to talk about the tremendous contribution of the Islamic astronomers," Ms. Burns said.

For medieval Islamic astronomers, there was an obvious challenge to find a simpler trigonometric method.

Al-Khazini is one of the few Islamic astronomers to be known for doing original observations.

Over 200 different zījes have been identified that were produced by Islamic astronomers during the period from the eighth to the fifteenth centuries.

Indian and Islamic astronomers estimated the size of Mars and its distance from Earth.

It was invented in ancient Greece and developed by Islamic astronomers.

His works inspired a generation of Islamic astronomers in Andalusia.

Islamic astronomers described other models of trepidation.