Three of today’s largest telescopes—Gemini North, Subaru, and Keck—stand within hailing distance of one another atop the nearly 14,000-foot peak of Hawaii’s Mauna Kea, an inactive volcano. The altitude puts them above 40 percent of Earth’s atmosphere—and most of its water vapor, which is opaque to the infrared wavelengths the astronomers like to study—but also makes it difficult for the astronomers and engineers who work there to breathe and think.

[Via National Geographic]