Both the North side and South Col of Mt. Everest are dangerous -- but in different ways.
Astronauts and satellites provide views of the top of the world from low-earth orbit.
Mt. Everest is a natural laboratory that continues to teach scientists lessons about how the body works and why lack of oxygen causes so many problems for climbers and heart failure patients.
Weather forecasting for Everest is better than it used to be, but huge mountains remain dangerously unpredictable.