On 15 February 2013, a 17–20 metre Apollo asteroid slammed into Earth's atmosphere over Chelyabinsk, Russia, releasing the energy of roughly 500 kilotons of TNT. Because it approached from the direction of the Sun, no telescope saw it coming. The impactor was on the outbound leg of its last orbit around the Sun — an Apollo-type path from the asteroid belt through perihelion near 0.76 AU in late December 2012, then back toward Earth. The simulation begins on 1 January 2013 with the asteroid still beyond the Moon, letting you follow its final weeks before atmospheric entry. The event remains the largest known airburst since Tunguska and a stark reminder of how blind spots in sky surveys can hide even significant near-Earth objects.