"Mountains are the beginning and the end of all natural scenery." - John Ruskin
According to the United Nations, December 11 is International Mountain Day. Mountains play a surprisingly important role in the ecosystems on Earth, providing most of the world's freshwater. Today, mountains entice people with the promise of adventure, snow during the summer months, and the exhilaration of sliding down their slopes on skis or boards. The tallest mountain in the world is Mt. Everest, standing tall at an impressive 29,029 feet. Hundreds of people flock to the mountain every year, hoping to be one of the few that manage to scale it. Perhaps in the future, people will attempt to scale Mars' Olympus Mons, standing a staggering 69,841 feet above the red planet's surface.