Astronomy ‘s Newest, Biggest Stargazer

Kyodo / Landov

The parabolic antennas of the Alma radio telescope on an Andean plateau in northern Chile on March 12, 2013.

Its not often you get to see a telescope dance, but thats exactly what happened in the thin, dry air of Chiles Atacama Desert on March 12. Thats when astronomys newest, biggest, most powerful stargazing machine was formally dedicated, after more than a year of preliminary operations. As the speeches from various political and scientific dignitaries came to a close, the Atacama Large Millimeter-submillimeter Array, or ALMA a set of 57 radio dishes perched on the Chajnantor Plateau, some 16,600 ft. (5,060 m) above sea level began to swivel and sway, in perfect, choreographed unison, as music filled a tent packed with scientific VIPs.

OK, maybe it was a little over the top, but ALMAs creators, including scientists and engineers from Europe, North America, Asia and Chile had the right to make a fuss. The $1.3-billion array is a technological tour-de-force that will produce images ten times sharper than the Hubble; study galaxies from the dawn of time; tease out the secrets of solar systems as they form; and more. Within a decade, says Leslie Sage, Senior Editor for Physical Sciences at the journal Nature, ALMA will have revolutionized astronomy more than the Hubble ever has.

Actually, that revolution has already begun. Even as ALMAs dishes were performing their coming-out ballet, astronomers were announcing that during its earlier, shakedown runs, the telescope had discovered surprising numbers of so-called starburst galaxies, where new suns are being born at a prodigious rate, just a billion years after the Big Bang which is a billion years earlier than anyone had expected.

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Last year, a team of observers used the array to detect the presence of unseen planets orbiting the star Fomalhaut, inferring the existence of the worldsby their effects on a ring of dust. These first results are spectacular, says Pierre Cox, ALMAs incoming director, and they were done with a limited number of antennasin the case of the planets, with just 15 of what will ultimately be 66 dishes, working in concert.

Thats one big reason the new telescope is so powerful: by combining the signals from all those dishes, ALMA can simulate a single dish as much as 10 miles (16 km) across. That makes ALMAs images preternaturally sharp. The powerful detectors at the heart of each dish, meanwhile, cooled to within a few degrees above absolute zero (-460F, or -273C) can sense the ping of incoming electromagnetic radiation with unprecedented sensitivity.

In this case, the radiation in question isnt ordinary visible light, but rather a form of light that lies in between the infrared and the microwave parts of the spectrum. Some astronomical phenomena, like the rings of cool dust that eventually turn into planets, naturally glow brightest in the millimeter-submillimeter part of the spectrum. Others, such as distant galaxies, start off with a smaller wavelength but their emissions are then stretched into the millimeter-submillimeter region as they cross a universe thats constantly expanding.

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Astronomy 's Newest, Biggest Stargazer

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