The moon has no core dynamo magnetic field, but spacecraft detect numerous strong localized magnetic fields in the crust of the moon. Many of these magnetic anomalies are antipodal to large impact basins. Scientists at Purdue University and the University of California, Santa Cruz, led by Brandon Johnson, Purdue associate professor of earth, atmospheric, and planetary sciences, ran impact simulations that showed that during oblique impact, ejected material piles up at the impact antipode.