The Light Falling on Mauna Kea

THE LIGHT FALLING ON MAUNA KEA/ Peter Musolf It is a kind ofbelieving without beliefthat we believe in. —Charles Wright THE SUMMIT of Hawaii's Mauna Kea is a broken circle of stark ridges and brown and red cinder cones surrounding a shallow, tilting valley. Light gushes down unimpeded, like water from a fire hose. Twenty miles to the south, the dark bulk of Mauna Loa, the island's other volcanic titan, shoulders through the clouds. To the northwest, seventy miles distant, neighboring Maui's Haleakala reminds me of a surfacing humpback. At 13,800 feet I feel giddy, but not simply because the oxygen is scarce. This place itself has raised a dizzying emotion in me, part terror at the sudden evidence of nature's inhuman scale, part exultation that even here a brave, inquisitive—and possibly absurd— handful of humanity has managed to find a foothold. These people are astronomers. Their observatories, eleven varying assemblages of sphere, cylinder and box, stand about the scene like exhibits in a lunar sculpture garden. One astronomer who uses these tools is a woman named Andrea Ghez, a gifted observer whose recent work has settled a long-standing debate by establishing that the center of our galaxy is a black hole. When an opportunity to meet Andrea came up, I jumped at the chance because my experience at the summit had unsettled me. Before Mauna Kea, I realized, the genuine scope of the world outside my personal dominion did not matter to me much. I was the biggest thing in the universe. Mountains and stars were just a pretty backdrop. Mauna Kea, though, shoved me out onto the real stage, a place Andrea had reached before me. Now I wanted to see the universe she sees, and I wanted to find out what the trick is to living peaceably with a full awareness of the natural world's immensity. I payAndrea a visit at her UCLAoffice on an early-September Friday, five months after my trip to the summit. Her door is half open, and as I enter she is gazing at a large computer screen filled with columns of close-packed numbers. There are two things you notice immediately about Andrea: her shoulder-wide frizz of brown hair and her eyes, which, when she turns them upon you, zap you with the intensity of 62 · The Missouri Review their gaze. Although they may spend more time focused on computer screens than on stars, they are the eyes you expect to find in an astronomer . Andrea's view of the distant and dust-clouded center of our galaxy is a good deal better than that of other astronomers. The fuzzy blob of light observers usually see resolves for her into a collection of distinct, individual stars. She manages this remarkable featby revving up her telescope's near-infrared camera with speckle interferometry, an imaging technique that Andrea has turned into the astronomical equivalent ofX-ray glasses. Speckle works by snapping up to ten pictures a second of a target area. One study can number exposures in the thousands, which Andrea later combines into a single image, averaging out the distortions caused when starlight passes through the earth's turbulent atmosphere. The final product looks like a small pinch of fine black pepper scattered upon a white plate. Each speck is a star. By the summer of 1998, Andrea was ready to summarize two years of intermittent midgalaxy observations. Since Kepler, astronomers have known that the period of an orbiting body and its distance from the gravity source it orbits are fixed. This means that if they can locate an orbiter and learn its velocity, they can determine its distance from the gravity dominating it. Using her perfected speckle-graph technique , Andrea located her stars precisely and nailed down their velocities . The movements of the ninety stars in her survey, she discovered, were being driven by the same nearby source of enormous gravity. How enormous? She calculated that the source pulls roughly 2.6 million times harder than the sun pulls on the earth. Where was it? Just where some people had been speculating it might be. WhatAndrea had in her specks was...