Mauna Kea: Hawaii
Take in the big night sky on the Big Island. The highest point in Hawaii, Mauna Kea is a dormant volcano with an elevation of nearly 14,000 feet. It's also the site of the world's largest and most advanced astronomical observatory. Three factors make this such a good stargazing spot; there's virtually no light pollution due to its location in the Pacific, a strong island-wide lighting ordinance and above all, a tropical inversion cloud layer that isolates it from the moist ocean air below. The result is dry, pollutant-free skies and tons of stars. One look and you'll understand why many astronomers consider the stargazing atop Mauna Kea to be the best on the planet.
Katahdin Woods and Waters National Monument (International Dark Sky Sanctuary): Maine
This International Dark Sky Sanctuary is located in western Maine, not far from the famous 100 Mile Wilderness, the most remote section of the Appalachian Trail. Mount Katahdin marks the beginning of the trail. At 5,269 it's the highest mountain in the state and the centerpiece of Baxter State Park. And yes, it sure is dark. Every September, the Friends of Katahdin Woods and Waters celebrate Stars Over Katahdin. The day-long event includes a campfire chat hosted by Dark Sky Maine followed by the chance to use a telescope with an expert astronomer on hand to assist you.
Central Idaho Dark Sky Reserve (International Dark Sky Reserve): Idaho
Less than three hours east of Boise, the Central Idaho Dark Sky Reserve encompasses nearly 1,500 square miles of the Sawtooth National Forest. This is America's first Gold Tier International Dark Sky Reserve. As such, they boast some of the darkest skies in the lower 48 and the chance to see the Milky Way, Andromeda Galaxy, and numerous satellites including the Space Station. Visitors can even see the Galilean Moons of Jupiter and the rings of Saturn with the aid of a small telescope.