(June 27) - More than 100 years ago, an enigmatic explosion devastated 80 million trees in a Russian forest. Today, researchers say the mystery known as the Tunguska event may be solved.
They say new evidence suggests a comet -- not a meteor as previously thought -- was behind the explosion. And, as the BBC reported, they're pointing to clouds that form thousands of miles away at Earth's polices to explain the theory.

Scientists claim these "noctilucent" clouds -- formations that are similar to what was seen after the Tunguska event -- reach the poles because water vapor appears to be quickly traveling in two dimensions, rather than three. The phenomenon, experts believe, happens when something like a magnetic field constrains the vapor, forcing it to move extremely fast in the remaining two dimensions.
Researchers noted this occurring when the shuttles Discovery and Endeavour launched in 1997 and 2003, respectively. The launches deposit tons of water into the upper atmosphere.
All of this, according to scientists, suggests a water-laden comet that shed its icy coating in that same part of the atmosphere is what flattened 830 square miles of Siberian forests in 1908, reported Examiner.com.
"It's totally new and unexpected physics," Michael Kelley of Cornell University told the BBC. "It's almost like putting together a 100-year-old murder mystery."