When it comes to ethanol, the United States may have reached its limit — at least for now. In 2007, Congress passed a law that would require the nation to use more ethanol and other biofuels each year. But for reasons of chemistry and economics, ...

Space is getting awfully messy. The amount of debris in Earth's orbit keeps multiplying each year, damaging satellites and putting astronauts in harm's way. If the problem gets severe enough, it could eventually make low-Earth orbit unusable. Scientists have known about the space trash problem ...

The U.S. job market is slowly improving, and most economists expect that gradual recovery to continue this year. Yet one of the most disturbing trends of the Great Recession is still very far from being reversed. America's middle-class jobs have been decimated since 2007, ...