Global Warming wiped out the Canals on Mars-
Man`s carbon dioxide pollution on Earth has spread rapidly in the last 150 years thru space to the Moon and beyond to the asteroid belt to Mars, wiping out the water canals that Leonardo da Vinci saw hundreds of years ago, causing Global Warming there, now devoid of all Martian civilization where there was vitality before. [sarc]
Could be a question to a man in the street by Jay Leno. :-)