Energy Efficiency

Jason Gillman / Morguefile

When a city replaces its old-fashioned streetlights with efficient LED lights, it can save a bundle of money on its electricity bills. But it can also dramatically increase light pollution, which is really unpleasant for astronomers and those among of us who like to do a little star-gazing on cloudless nights. The kind of light these LEDs emit can cloud our view of constellations.