20-ton Mirror Cast in Rotating Fire May One Day Help Unlock Mysteries of the Universe

The third in a series of seven 20-ton mirrors that will one day comprise the Giant Magellan Telescope (GMT) was cast inside a rotating furnace at the University of Arizona's Steward Observatory Mirror Lab (SOML) on Saturday, marking another milestone in the construction of a telescope that, once complete, will be capable of capturing images 10 times sharper than the Hubble Space Telescope.

Constructed from borosilicate glass, the mirror was spun cast in a furnace reaching 2,140 degrees Fahrenheit and measures a total of 27 feet across.

Despite this massive size, the mirror's surface must be smooth within a twentieth of a wavelength of light after it is polished in order to work.

Upon completion, all seven mirrors will be pieced together to form a single mirror 80 feet in diameter, bringing starlight to a common focus with the help of a set of secondary mirrors configured in a similar pattern. The resulting power, according to those behind the $700 million project, will enable scientists to gain new insight into astronomy's most pressing questions, including the identification of planets outside our solar system, the nature of dark matter and dark energy, the physics behind black holes and the evolution of stars and galaxies.

"The giant mirrors being spun cast for the GMT at the Steward Observatory Mirror Lab are like the sails of the great ships of exploration ca. 1500, except here the discoveries are not lands across the ocean, but rather the nature of whole new worlds and island universes, spanning all of space and time," Joaquin Ruiz, Dean of the College of Science at  the University of Arizona, said in a statement.

The GMT is currently scheduled to begin operations in 2020 at Las Campanas Observatory located in the Atacama Desert in northern Chile.