Mega Mirror To Power Massive New Telescope

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One upon a time, the largest glass telescope mirror was 100 inches in diameter. Today, scientists are casting a mirror 27 feet in diameter that will be part of one of the most powerful telescopes on Earth. NPR's Joe Palca speaks with weekends on All Things Considered host Guy Raz from the mirror laboratory, located under the football stadium at the University of Arizona.


Later today, the temperature inside a giant spinning furnace in Tucson, Arizona will reach 2,140 degrees Fahrenheit. Twenty-one tons of glass will become molten and flow into a honeycomb frame. The goal is to make a giant mirror 27 feet across. It'll be one of the seven mirrors that make up the giant Magellan telescope. That's the telescope being built in the Andes Mountains in Chile.

NPR's Joe Palca is at the mirror lab at the University of Arizona, and he joins me on the line from there. Joe, describe where you're standing right now.

JOE PALCA, BYLINE: So now, I'm standing right over this spinning giant furnace. It's a - like a giant merry-go-round, and it's got this glass that's slowly being heated up, and it will begin to flow into this honeycomb mold. But I'm going to step away from here because it's really noisy.

RAZ: So, Joe, explain what will happen once this mirror is mounted. What will we be able to see in outer space that we cannot see right now?

PALCA: Well, the whole name of the game in astronomy is getting photons into your telescope. The larger the mirror, the more photons you get. And this is also going to get very high resolution. So they expect that they may actually be able to image planets going around stars with this telescope. And they also think they may be able to use it to look way back to the earliest things that formed in the universe and that will inform theories about how the universe was created in the first place.

RAZ: When will this all be ready?

PALCA: They're aiming for 2020.

RAZ: Oh, man.

PALCA: But telescopes tend to slip, and when money is short, things slow down. So 2020 is the optimistic start.

RAZ: So, Joe, we have to wait eight years before we can see some of these images.

PALCA: Yeah. It's - and this is only the second. They've got five more mirrors to make. So they're actually beginning to start what they hope will be a mirror here until they're finished, and then they'll begin shipping them down to Chile.

RAZ: All right. You promise to update us in 2020?


PALCA: Absolutely.

RAZ: That's NPR's Joe Palca at the mirror lab at the University of Arizona. Joe, thanks.

PALCA: You bet.

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