US power grid costs rise, but service slips

America's power grid is like an old car. It gets the job done, even if its performance is slipping. But the repair bills go up every year and experts say only a major overhaul will reverse its decline.

Kepler's supernovae

(—Supernovae, the explosive deaths of massive stars, are among the most momentous events in the cosmos because they disburse into space all of the chemical elements that were produced inside their progenitor stars, ...