- Caelum /ˈsiːləm/ is a faint constellation in the southern sky, introduced in the 1750s by Nicolas Louis de Lacaille and counted among the 88 modern constellations. Its name means “chisel” in Latin, and it was formerly known as Caelum Sculptorium (“Engraver’s Chisel”); it is a rare word, unrelated to the far more common Latin caelum, meaning “sky”, “heaven”, or “atmosphere”. It is the eighth-smallest constellation, and subtends a solid angle of around 0.038 steradians, just less than that of Corona Australis.
- The Illusions Index (illusionsindex.org)
The Illusions Index is a fully searchable, interactive curated collection of illusions. The illusions are categorised into different types, allowing you to search for, and compare, illusions that fall under one or more type. Staff and students at the Centre for the Study of Perceptual Experience have researched each illusion to provide detailed information about what it teaches us about the philosophy and psychology of perception.
