The Northern Lights are among the world's most awe-inspiring sights. For centuries they've commanded reverence from various cultures, each with its own interpretation on the lights' origins. Today we know they're caused by solar winds interacting with charged particles in the Earth's magnetic field. The results are glowing streaks of light moving across the sky in vibrant hues of green, yellow, purple, and red. Although several of the most famous aurora-viewing destinations, such as Norway, Sweden, and Denmark, are expensive countries to visit, other locales offer prime vantage points to travelers on limited budgets. There's no guarantee the lights will glow on any given night, but picking the right location increases the odds of getting your money's worth.