# Celestial sphere The null infinity of 4d Minkowski space = celestial sphere cross the null line. The celestial sphere is therefore a two-sphere, and it is where the [[0010 Celestial holography|celestial CFT]] lives. ## Relevant topics - see difference to ordinary CFT at [[0041 CFT vs CCFT]] - [[0250 Celestial torus]] ## Modifications - [[BanerjeeGhoshPandeySaha2019]] - modified celestial amplitudes - lives on 3d null infinity