There are a lot of good things to say about Maui (Hawaii's second biggest island) in winter: temps are cooler; big-wave surfing kicks up along the North Shore and whale watching is at its best, as humpbacks winter in the warm, shallow waters just offshore. What's more, at 10,000 feet, near the top of Haleakala volcano, Haleakala National Park has some of the best night sky conditions in the world. The visual horizon stretches away as far as 115 miles out to sea, offering a nearly 360-degree view of the sky. And, with hardly any cities (not to mention the black expanse of the Pacific Ocean) within a 2,300-mile radius, there's almost no light pollution, allowing you unfettered views of the heavens. Rent binoculars from an island dive shop, pick up a star map from one of the park's visitor centers and you may be able to spot the moons of Jupiter.