National Geographic News
Space picture: The Antennae Galaxies as seen by a new observatory.

ALMA's new view of the Antennae Galaxies, combined with data from the Hubble Space Telescope.


Victoria Jaggard

National Geographic News

Published October 3, 2011

The Antennae Galaxies glow with psychedelic colors in the first publicly released picture that uses data from the Atacama Large Millimetre/sub-millimetre Array, or ALMA, a new telescope high in Chile's northern desert.

Similar in design to radio telescope arrays, the internationally funded ALMA is being hailed as the most complex ground-based observatory yet built. When construction is complete in 2013, the array will feature 66 antennas spread across 9.9 miles (16 kilometers) that will be linked with fiber optics to function as a single telescope.

(See a picture of an ALMA antenna being driven up Chile's Chajnantor plateau.)

"We've been waiting a very long time to get to the point where ALMA is really able to do science. Some people have been working on this project for more than 20 years," project scientist Richard Hills told the AFP news service.

"So it has been a long road, but all the bits and pieces that we need to make this telescope work now [are coming] together."

New Telescope Needs to Be High and Dry

ALMA is designed to detect millimeter and submillimeter wavelengths, which have much longer waves than visible light.

Unlike radio waves, which pass easily through Earth's atmosphere, submillimeter waves are blocked by water vapor, a common gas in the lower atmosphere. That's why ALMA sits 16,400 feet (5,000 meters) above sea level, in a dry environment that minimizes atmospheric distortions.

(Find out how studies of extreme microbes in the Atacama Desert may aid the hunt for life on other worlds.)

By detecting millimeter and submillimeter wavelengths with unprecedented resolution, ALMA will help uncover some of the darkest, coldest, and most distant objects in the universe.

The above image, for example, showcases the Antennae Galaxies, a pair of colliding galaxies 70 million light-years from Earth. The galaxies can be seen in visible light—this picture includes optical and infrared data from the NASA/ESA Hubble Space Telescope. But while the optical data show the galaxies' brightly glowing newborn stars (blue), the millimeter data from ALMA reveals the otherwise invisible clouds of cold gas from which these stars are forming (red and yellow).

(See Hubble's sharpest picture of the Antennae Galaxies.)

ALMA's "first light" picture was made during a test of the array's systems in preparation for the first round of science observations. Scientists captured most of the data for this picture using just 12 of the working antennas.

Over the next nine months, astronomers around the world will conduct the first hundred ALMA science projects, including investigations of the supermassive black hole at the center of the Milky Way, the formation of planets around other stars, and the first galaxies that formed shortly after the big bang.

(Related: "Mysterious Structures Balloon From Milky Way's Core.")

One of the first ALMA projects, for instance, will be led by David Wilner from the Harvard–Smithsonian Center for Astrophysics in Massachusetts. His team will examine the disk of planet-forming debris around AU Microscopii, an extremely young star 33 light-years away.

"We will use ALMA to image the 'birth ring' of planetesimals that we believe orbits this young star," Wilner said in a press statement. "Only with ALMA … can we hope to discover clumps in these dusty asteroid belts, which can be the markers of unseen planets."



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