How bright is Asteroid 99942 Apophis?
The current visual magnitude of Asteroid 99942 Apophis is 16.19. Given its brightness, Asteroid 99942 Apophis should be visible with the help of a telescope havng an aperture of 20 inches (500mm) or more.
The following chart is the predicted light curve (visual magnitude as a function of time) of Asteroid 99942 Apophis, according to the most recent ephemerides data. Magnitude data is sampled with a 2 days interval and there might be inaccuracies for objects changing brightness very rapidly during the course of a few days. For comets there could be large discrepancies between the observed and predicted brightness because of their highly dynamic behaviour.