In order to protect against such events (or at least reduce their effects), NASA has developed ways to monitor near-Earth objects. For example, NEAR (Near-Earth Asteroid Rendezvous) is a spacecraft that monitors Eros, one of the largest asteroids being studied. Eros is scheduled for a near-Earth approach on January 31, 2012. This huge flying rock is the shape of a potato, and its size is 442 square Km. Scientists believe that it might strike the Earth in 1.5-5 million years. The probability of one of these NEOs hitting the Earth over the next hundred years is virtually negligible. However, scientists are concerned, because at present there are about 900 asteroids circulating our solar system.