On average, an asteroid the size of Apophis (370 metres) is expected to impact Earth once in about 80,000 years. … 99942 Apophis. Model of 99942 Apophis’s shape, assuming the entire surface is of a similar composition.DiscoveryDiscovered byRoy A. Tucker David J. Tholen Fabrizio Bernardi99942 Apophis – Wikipedia en.wikipedia.org › wiki › 99942_Apophis