Very Large Telescopes

The Earth’s most powerful telescope goes online next weekBy Annalee Newitz, io9.com

We are about to see what happens when stars come to life. On March 13, the Atacama Large Millimeter/Sub Millimeter Array (ALMA) goes online. It's the most powerful such telescope ever built, and is part of a class of "very large telescopes" that combine the power of several massive antennae to gather information about distant regions in the universe. ALMA is in northern Chile's high desert, 16,500 feet above sea level. And it will show us things about the universe we've never seen before.

EarthSky's Emily Howard has the story:
　

According to the scientists, one nation alone couldn't build ALMA. Working with the host country Chile, some of the largest observatories in the world joined together for ALMA. These include the National Radio Astronomy Observatory in North America, the European Southern Observatory, and observatories in Japan, Brazil and throughout Latin America.

Sixty-six large radio dishes connect together to form ALMA. These dishes are located 30 minutes by car from the town of San Pedro de Atacama in Chile – at the top of the world – at an altitude of 16,500 feet, or 5,000 meters.

At that height and in the desert, there is little water vapor in the air. Those conditions are perfect for ALMA because water in the air blocks starlight in the portion of the "electromagnetic spectrum" that scientists want to study.

ALMA will observe starlight at wavelengths invisible to your eye – the long infrared wavelengths of starlight. Space observatories, like the Hubble Space Telescope, orbit high above the blanket of Earth's atmosphere to see the universe at these wavelengths. Astronomers hope that ALMA will be even better than space telescopes at exploring the infrared universe – because they can build it much larger on land than they can in space today.

Because ALMA can pick up these long wavelengths of light, it will help astronomers explore the cool, chemically complex dust that surrounds newborn stars and planets. One goal of the project is to understand star formation — and, hopefully, a phase in our early universe when galaxies went through what you might call a "star boom." Basically, many stars were spawned at once. ALMA may help astronomers understand what catalyzed this boom.

Before all of ALMA's telescopes had been constructed, the array had already provided data to scientists that allowed them to discover how galaxies make new stars when they collide. The image above is of the Antennae Galaxies, which are in the middle of a smashup. Below, you can see ALMA's millimeter and submillimeter light view, which reveals areas of intense star formation in the dust. Remember, this was an image created when ALMA wasn't complete — images from the fully functioning array will be much sharper.

ALMA isn't the only giant telescope that's coming online in the highlands of Chile. Over at the Simons Foundation, Natalie Wolchover has a great overview of the next generation of extremely large telescopes. She writes:
　

The huge telescopes will look back in time at some of the earliest light ever emitted by objects. The universe inflated like the surface of a balloon shortly after the Big Bang, and some places stretched so far from here that their first bursts of light are only now arriving. Resolving this light would reveal the structure and chemical makeup of the universe's first objects, which, as faint images from the Hubble Space Telescope suggest, developed much earlier than current theories would predict. Better observations are likely to lead to new theories of the birth and evolution of space and time, Gilmore said.

　

At projected costs ranging from $900 million to $1.6 billion each, the Giant Magellan Telescope, the Thirty Meter Telescope and the European Extremely Large Telescope - which will have segmented mirrors measuring 24.5 meters, 30 meters and 39.3 meters across, respectively - will dwarf existing optical telescopes (the current largest is 10.4 meters). They will be between 5 and 200 times more powerful, depending on the telescope and the task.

These telescopes will be able to explore everything from galaxy formation to weather on planets in other solar systems. They'll also be able to peek into the history of our universe, plumbing the mysteries of the origins of space and time as we know them.

http://io9.com/5989612/the-most-powerful-telescope-ever-constructed-goes-online-next-week