When the most distant object in the known universe first appeared on a photograph taken through the Sloan Digital Sky Survey telescope at Apache Point, New Mexico, the astronomers on watch had no idea what they'd stumbled upon. The dim speck was barely visible under extreme magnification and looked utterly unremarkable amid several thousand points of light scattered across a swath of the northern sky. The treasure in the star field remained hidden until the digital photo was scrutinized at the Fermi National Accelerator Laboratory near Chicago by a cluster of powerful computers equipped with advanced image-processing software that notes the color and shape of each point of light.
EYE ON THE SKY: Perched on a 9,200-foot peak in the Sacramento Mountains of south-central New Mexico, far from any large cities, the Sloan Digital Sky Survey's 2.5-meter telescope peers into a night sky that is among the darkest in the United States. The atmosphere at the site is remarkably free of water vapor or pollutants that degrade celestial images.
Usually, a blob of light denotes a galaxy and a pinpoint of light means a star. But the computer indicated this pinpoint was too red to be an ordinary star. So the Sky Survey's astronomers took a closer look with the powerful Keck telescope atop Mauna Kea, Hawaii. They made a spectrogram that provided a more precise breakdown of the light's constituent colors, revealing what it is made of and where in space it is actually located. "As soon as the spectrum came up on the screen," recalls Princeton astrophysicist Michael Strauss, "it was obvious to everyone in the control room what we'd found." The speck of light was a distant quasar—a celestial powerhouse with a giant black hole at its center that sucks in primordial matter and heats it to an incandescence exceeding that of a trillion stars. This quasar's light began the 12-billion-year journey from the outermost edge of the universe to Earth less than 1 billion years after the Big Bang, making it the oldest heavenly object humans have ever seen. "We were," says Strauss, with a touch of nonchalance, "pretty excited."
No wonder. Finding record-breaking quasars—the Sky Survey has now snagged the four furthest away from Earth—is already giving astronomers invaluable information about the epoch when the first quasars and galaxies lit up and burned through the fog of opaque gas that filled the universe following the Big Bang. The project, run by a consortium of labs and universities that includes Fermilab, Princeton, the University of Chicago, and Johns Hopkins, has also discovered thousands of new asteroids in our own solar system and located more than 20 brown dwarfs—objects that are bigger than a planet but smaller than a star and which may be a key to understanding the process of planet formation.
