Ever wonder why the red planet is red? About 180 million years ago, a planet-shattering yet naturally occurring nuclear reaction may have wiped out everything on Mars, sending a shockwave that turned the planet into dry sand. Even more incredible: A natural nuclear reaction could have occurred on our own planet -- and could happen again, said Dr. John Brandenburg, a senior propulsion scientist at Orbital Technologies Corp. "The Martian surface is covered with a thin layer of radioactive substances including uranium, thorium and radioactive potassium -- and this pattern radiates from a hot spot [on Mars],” Brandenburg told FoxNews.com. “A nuclear explosion could have sent debris all around the planet," he said. "Maps of gamma rays on Mars show a big red spot that seems like a radiating debris pattern ... on the opposite side of the planet there is another red spot." According to Brandenburg, the natural explosion, the equivalent of 1 million one-megaton hydrogen bombs, occurred in the northern Mare Acidalium region of Mars where there is a heavy concentration of radioactivity. This explosion filled the Martian atmosphere with radio-isotopes as well, which are seen in recent gamma ray spectrometry data taken by NASA, he said. The radioactivity also explains why the planet looks red. More Was There a Natural Nuclear Blast on Mars?