The visibility of Venus

Albert J. Ahumada, NASA Ames Research Center, al.ahumada@nasa.gov NASA Ames Research Center Abstract Venus is the only planet or star that can be seen by the naked eye during the day. Following the method of Westheimer (1985) for representing a point source as a single pixel on a screen with a resolution of 120 pixels per degree, we can convert the magnitude of Venus and the sky luminance into a luminance contrast signal with a contrast of 2.22. Detection models calibrated to the Modelfest data predict that such a target is below threshold (Watson and Ahumada, 2005). Modifications are proposed to the models to keep Venus visible.