It was a busy weekend at the Steward Observatory Mirror Lab. On Saturday, the lab's technicians cast 20 tons of molten glass into an ultra-precise parabolic mirror—the third of seven. By 2020, the mirrors will have been transported to Chile's arid Atacama Desert and assembled into the new kid on the cosmological block: the Giant Magellan Telescope.
Using adaptive optics, an 80-foot aperture, and a honeycomb structure, the GMT will record deep space images 10 times sharper than the Hubble. It will be the highest resolution telescope ever made, and it won't even have to leave the planet.
The GMT owes its high precision to its meticulously crafted design. The mirror cast over the weekend will require a full year of polishing until it is within 1/20 the wavelength of light. That's a light tolerance level of one part per billion. To get a sense of the scale, imagine the mirror is the size of the United States. The tallest mountain on the surface would be about an inch high. In short: these mirrors are the smoothest thing to grace the Earth since Robert Downey Jr.
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