... QR Codes: Not for Human Eyes . ... What if you could fly through the universe and see dark matter? ... Tunguska: The Largest Recent Impact Event . ... The most powerful natural explosion in recent Earth history occurred on 1908 June 30 when a meteor exploded above the Tunguska River in Siberia, Russia. ... Cocoon Nebula Wide Field . ... Dry Ice Pits on Mars . ... During 2006, a large solar flare from an Earth-sized sunspot produced a tsunami-type shock wave that was spectacular even for the Sun. ...