Washington, Apr 2: Ever wondered why Mars is red? According to a scientist, 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.

"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],” Dr. John Brandenburg, a senior propulsion scientist at Orbital Technologies Corp, told Fox News.

“A nuclear explosion could have sent debris all around the planet.

"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," he added.

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. (ANI)