Hurricanes
A hurricane is a giant heat engine powered by warm ocean water, and when it runs out of fuel it falls apart.
Plate Tectonics
A theory that explains why South America and Africa's coastlines look like they'd fit together — because, hundreds of millions of years ago, they did.
Renewable Energy
Within about a decade, solar and wind went from pricey idealistic alternatives to cheaper than fossil fuels in many regions.
Ocean Currents
The Gulf Stream helps keep Western Europe mild, and scientists worry melting polar ice could disrupt the circulation behind it.
Climate Change
The greenhouse effect keeps Earth livable. The trouble began when human emissions started piling extra on top, around the industrial era.
Earthquakes
Most earthquakes are too small for any human to feel, caught only by seismometers quietly logging the ground's tiny movements.
Volcanoes
About 75% of the world's active volcanoes crowd into one Pacific horseshoe, aptly nicknamed the Ring of Fire.