National Geographic : 2017 Aug
Even on the starriest of nights, the human eye sees just a tiny fraction of the cosmos. So if the curve of the Big Dipper or the four points of the Southern Cross appear magnificent, consider how many more phenomena must exist out of view. That prospect is what led astrono- mer Natasha Hurley-Walker to a radio telescope deep in the outback of West- ern Australia. The telescope, called the Murchison Widefield Array, is made up of thousands of antennas that see through celestial dust and detect “radio light”—revealing colors and objects in a spectrum not visible to humans, even with the aid of optical telescopes like Hubble. Stretched across nearly four square miles of desert, the antennas— cheaper to produce and maintain than typical dishes—look like “an army of mechanical spiders,” she says. In the past four years, Hurley-Walker and a team of researchers—from the In- ternational Centre for Radio Astronomy Research in Perth as well as other insti- tutions in Australia and New Zealand— have stitched together more than 40,000 images taken by the telescope. The result is a groundbreaking por- trait of the entire southern sky. It exposes hundreds of thousands of galaxies mil- lions of light-years away. And it shows in unobscured, blazing color the radio glow of the Milky Way, lit up with the remains of exploded stars and intense magnetic fields. This sweeping survey, says Hurley-Walker, “allows people to see the sky with radio eyes.” Her research is far from finished. Hurley-Walker is now working with an international team to develop a radio telescope many times bigger and more sensitive than the Murchison Widefield Array. Its technology could pick up faint- er signals, which would unveil millions more galaxies and—if her wish comes true—“the birth of the very first stars.” ARRAY OF LIGHT By Catherine Zuckerman EXPLORE SPACE GAMMA RAY X-RAY VISIBLE In this composite image, the Milky Way and radio galaxy Centaurus A glow in the southern night sky above a section of the Murchison Widefield Array telescope. Below, the center of the Milky Way is shown at various wavelengths.