Hawaii, United States
At the 14,000 feet above sea level on Hawaii's Mauna Kea, there are clear skies 90 percent of the year, making the volcanic mountain attractive to astronomers. It's no wonder, then, that 11 countries have set up shop there, making it home base for some of the biggest telescopes in the world. For visitors who don't want to deal with the altitude sickness at the top, below the summit—but still at an impressive 9,300 feet above sea level—there's the Onizuka Center for International Astronomy Visitor Information Station. There, you can find telescopes available for public use—including a solar telescope, fitted with protective filters, that'll let you actually stare at the sun. (Take that, Mom.) The Visitor Information Station also hosts free nightly stargazing programs.
Visit: The Onizuka Center for International Astronomy Visitor Information Station is open every day from 9 am until 10 pm. There are tours to the observatories at the summit every Saturday and Sunday at 1 pm, but visitors must provide their own 4-wheel-drive vehicle with low range to participate in the tour.
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