World's largest mirror cast successfully

After slowly heating the mirror's glass to a maximum temperature of 2,165 degrees Fahrenheit, the mirror's mold was rotated for 70 hours during the initial phase of cooling. It will now take about 12 weeks for the mirror to completely cool, according to a University of Arizona news release.

"I feel very good," said John Hill, project director for the Large Binocular Telescope at Steward Observatory. "I've been working on this for over 16 years."

The mirror is the world's largest ever cast. It is one of two that will be mounted on the LBT at the Mount Graham International Observatory.

Together the mirrors will have the light-gathering power of one 11.8-meter instrument and the image sharpness of a 22.8-meter mirror, making it the most powerful telescope in the world.

Peter Strittmatter, Steward Observatory director, called the 17-ton mirror a major milestone.

"We are extremely pleased with the success of the casting at this stage in the process," Strittmatter said.

"This stands as a very historic moment for the mirror lab, the university and the LBT Project," he said.

Hill said there is a possibility of Germany and Ohio State University joining the project.

The project is a collaboration between the UA, Italy's astronomical community and the Tucson-based Research Corporation.

Roger Angel, scientific director of the Mirror Lab and UA regents professor of astronomy, said the UA mirror lab will be casting two mirrors for a telescope larger than the LBT on Mount Graham.

The mirrors will not be larger than the 8.4-meter mirror but will have greater light-gathering power, he said.

"This telescope will enable research at the cutting edge in almost all areas of astronomical disciplines, including the origins of our universe, the formation of galaxies and the exploration of other solar systems," Angel said.