Abraham Ben Chaja [Chija] (1070 - 1105)
Ben Chaja was born around 1070 in Barcelona, Spain. He was a pupil of Rabbi Moses Haddarschan . Ben Chaja is said to have been a great astronomer and wrote some works on Astronomy and Geography. One tells about the form of the earth, the elements and the structure of the spheres. (Manuscripts may be in the Vatican, in Vienna and Paris). This work was printed in Basel by Oswald Schreckenfuchs, including a latin translation.

Other works included papers on astrology, trigonometry and music.Ben Chaja was called 'the great Astronomer', he died after 1105. Ben Chaja was the teacher of Ben Esra.

Reference(s):
Allgemeine Enzyklopädie der Wissenschaften und der Künste, Part 1, Vol. 1, p. 157
Illustr. Lexikon der Astronomie, by Adolph Drechsler, Verlag J.J. Weber, Leipzig 1881, p. 5
Pogg. Vol. I, p.5