Mysteries of the Universe

“THERE ARE MORE THINGS IN HEAVEN and earth, Horatio, Than are dreamt of in your philosophy.” Hamlet was speaking of ghosts and murder, but he might well have been summarizing the past decade of scientific discovery, described by one prominent astronomer in these pages as “spectacular in terms of achievements.” In that time Pluto was demoted from its status as a planet but, weighed against the loss, researchers peering into the universe with powerful new telescopes and space probes have discovered 500 planets beyond our solar system; gathered extraordinary images from the recently tuned-up Hubble Space Telescope; scanned radio signals in search of extraterrestrial life; drilled into the rock of Mars; discovered new rings of Saturn; tracked the trajectory of potentially catastrophic asteroids hurtling toward Earth; and looked toward the dense…

FROM THE SUMMIT OF MAUNA KEA, nearly 14,000 feet above the Pacific Ocean, the Milky Way tilts luminously across the night sky, an edge-on view of our galaxy. Parts of the great disk are obscured by dust, and beyond one of those dusty blots, near the teapot of the constellation Sagittarius, lies the center of the Milky Way. Hidden there is a deeply mysterious structure around which more than 200 billion stars revolve. Behind me atop the craggy rocks of this dormant volcano on the island of Hawaii are the twin domes of the W. M. Keck Observatory. Each dome houses a telescope with a giant mirror almost 33 feet wide and, like a fly’s eye, made of interlocking segments. The mirrors are among the world’s largest for gathering starlight, and…

SINGULARITY The center of a black hole, called a singularity, is infinitely dense. Nothing, not even light, can escape its gravity—making it impossible to observe directly. What happens to all the space dust, planets and even stars that are pulled into the black hole’s singularity? “The ultimate fate is not known,” says astrophysicist Avi Loeb. EVENT HORIZON The edge of a black hole, or its event horizon, is where the gravity becomes strong enough to hold light. ACCRETION DISK The gas and dust and other matter that are drawn toward a black hole form an accretion disk. The matter heats up as it spirals toward the event horizon, radiating X-rays that reveal the black hole’s location and mass.…

INSIDE A GLASS CASE WAS A PLAIN-LOOKING TUBE, worn and scuffed. Lying in the street, it would have looked like a length of old pipe. But as I approached it, Derrick Pitts—only half in jest—commanded: “Bow down!” The unremarkable-looking object is in fact one of the most important artifacts in the history of science: it’s one of only two surviving telescopes known to have been made by Galileo Galilei, the man who helped revolutionize our conception of the universe. The telescope was the centerpiece of “Galileo, the Medici and the Age of Astronomy,” an exhibition at the Franklin Institute in Philadelphia in 2009. Pitts, who runs the institute’s planetarium and other astronomy programs, says that receiving the telescope from Florence’s Galileo Museum—the first time the instrument ever left Florence—was “something of a…

WE’RE AWASH IN NEUTRINOS. They’re among the lightest of the two dozen or so known subatomic particles and they come from many sources: from the Big Bang that began the universe, from exploding stars and, most of all, from the Sun. They come straight through Earth at nearly the speed of light, all the time, day and night, in enormous numbers. About 100 trillion neutrinos pass through our bodies every second. The problem for physicists is that neutrinos are impossible to see and difficult to detect. Any instrument designed to do so may feel solid to the touch, but to neutrinos, even stainless steel is mostly empty space, as wide open as a solar system is to a comet. What’s more, neutrinos, unlike most subatomic particles, have no electric charge—they’re neutral,…

MOST OF US DO WHAT WE CAN for the environment, but Rik Hill’s actual job is to protect the planet. “Look at that!” he says, pointing at a moving blip of light on a computer screen. “It’s an unknown object. We just discovered one.” We’re in an observatory on the summit of Mount Lemmon, a 9,000-foot peak north of Tucson, Arizona. Hill’s boss, Ed Beshore, leans in and nods. “That’s an NE-O,” he says, referring to a near Earth object. “It’s a nice one. It’s bright, and it’s moving fast.” Hill, an astronomer, sends an e-mail to the Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, where the Minor Planet Center monitors hundreds of thousands of small bodies in our solar system. The message gives the object’s coordinates at the time of its discovery so…