ANTENNAE ON THE MARCH
Each 230-ton radio telescope in the Very Large Array rides on a Y-shaped stretch of railroad track in the desert near Socorro, New Mexico. Three times a year the telescopes change formation to zoom in on small details or pull back to get the big picture.
In 1932, a Bell Telephone Laboratories engineer named Karl Jansky was hunting down sources of radio static when he detected a persistent noise coming from one part of the sky. The source, as it turned out, was some cosmic unrest at the heart of the Milky Way. No optical telescope could see past impenetrable clouds of gas and dust. But Jansky’s radio could hear what was happening.
Since then, astronomers have confirmed that the best way to learn about deep space is often to tune in to its hissy song. And hundreds of millions of dollars have been spent on ever-more-ambitious devices for doing so. For example, the radio telescope built in 1963 in Arecibo, Puerto Rico, stretches 1,000 feet across a small valley. With it, astronomers have listened to the rapid spinning of burned-out stellar corpses and discovered an improbable family of planets serenely circling one of them. The Japanese government recently launched a radio telescope into space itself, and next year nasa will loft another satellite to study the short-wavelength radio waves left over from the time of the Big Bang.
Still, no telescope inspires more awe than the Very Large Array, completed in 1980. Its 27 radio dishes, each 82 feet wide, stand in formation across the New Mexico desert like a set of abandoned alien spacecraft. A series of computers and electronic connections unites them into one huge telescope, 22 miles wide. The whole gargantuan herd, called the vla for short, lumbers along railroad tracks to form different patterns that adapt to scientists’ needs.
The array can transform feeble radio signals into spectacular images. Unlike light waves, radio waves are long enough—about an inch to a yard for the images in this article—to leap right over bits of interstellar debris. And while light comes mostly from stars, radio waves emerge from many kinds of cosmic disturbances. Seen through a traditional telescope, light from the galaxy M87 shows little more than a fuzzy ellipse of stars. A new vla image reveals twin jets of gas shooting from that galaxy’s center, inflating a placenta of energized gas 200,000 light-years wide. The jets originate in a compact object at the galaxy’s center, probably a black hole weighing as much as three billion suns.
Nearly every discovery is a surprise where this still-infant technology is concerned. Just recently, the Very Long Baseline Array—10 matched telescopes, linked together to form an instrument effectively 5,000 miles wide—baffled researchers with the news that the universe is smaller and younger than was previously thought. They’ll just have to keep tuning in to see what comes next.
By sweeping his rotating radio detector back and forth, Bell
Labs engineer Karl Jansky identified the first deep-space radio signals.
THE BIG PICTURE
The cobe satellite, launched in 1989, carried the study of microwaves into space and confirmed that the universe began in a hot fireball.
In 1993 a star blew up in nearby galaxy M81, sending a shell of hot, radioactive gas speeding outward at thousands of miles per second.
The tremendous resolving power of the Very Long Baseline Array allowed astronomers to watch as the irregular shell of gas expanded into the interstellar medium.