Editing Ibn al-Haytham (section)

=== Celestial physics ===
Alhazen discussed the [[physics]] of the celestial region in his ''Epitome of Astronomy'', arguing that Ptolemaic models must be understood in terms of physical objects rather than abstract hypotheses{{snd}}in other words that it should be possible to create physical models where (for example) none of the celestial bodies would collide with each other. The suggestion of mechanical models for the Earth centred [[Ptolemaic model]] "greatly contributed to the eventual triumph of the Ptolemaic system among the Christians of the West". Alhazen's determination to root astronomy in the realm of physical objects was important, however, because it meant astronomical hypotheses "were accountable to the [[Physical law|laws of physics]]", and could be criticised and improved upon in those terms.<ref>{{harvnb|Duhem|1969|p=28}}.</ref>

He also wrote ''Maqala fi daw al-qamar'' (''On the Light of the Moon'').