Think of Hawaii, and you will conjure up a picture of palm trees, guitars, bikinis and an azure blue sea. Many parts of it really are like this, but go to Big Island and you will find a different scene. There are two towering volcanoes, one dormant and the other violently active. You will also find one of the world’s greatest observatories. Why Mauna Kea? Because it is so lofty, and pokes above the thickest and unsteadies layers of an atmosphere. Not much life can survive – but astronomers love it, and the summit positively bristles with domes.