How to Build an 80-foot-wide Telescope Mirror to See Deep Space – By Buddy Martin, University of Arizona, Dae Wook Kim, University of Arizona, The Conversation on January 15, 2016


Two scientists working on the Giant Magellan Telescope explain the mammoth and intricate construction

Artist’s concept of the completed Giant Magellan Telescope which will be situated in the Atacama Desert some 115 km (71 mi) north-northeast of La Serena, Chile. GMTO Corporation/Wikimedia Commons

When astronomers point their telescopes up at the sky to see distant supernovae or quasars, they’re collecting light that’s traveled millions or even billions of light-years through space. Even huge and powerful energy sources in the cosmos are unimaginably tiny and faint when we view them from such a distance. In order to learn about galaxies as they were forming soon after the Big Bang, and about nearby but much smaller and fainter objects, astronomers need more powerful telescopes.

Perhaps the poster child for programs that require extraordinary sensitivity and the sharpest possible images is the search for planets around other stars, where the body we’re trying to detect is extremely close to its star and roughly a billion times fainter. Finding earth-like planets is one of the most exciting prospects for the next generation of telescopes, and could eventually lead to discovering extraterrestrial signatures of life.

Detectors in research telescopes are already so sensitive that they capture almost every incoming photon, so there’s only one way to detect fainter objects and resolve structure on finer scales: build a bigger telescope. A large telescope doesn’t just capture more photons, it can also produce sharper images. That’s because the wave nature of light sets a limit to the telescope’s resolution, known as the diffraction limit; the sharpness of the image depends on the wavelength of the light and the telescope’s diameter.

As optical scientists, our contribution to the next generation of telescopes is figuring out how to craft the gargantuan mirrors they rely on to collect light from far away. Here’s how we’re perfecting the technology that will enable tomorrow’s astrophysical discoveries.

Article continues:

http://www.scientificamerican.com/article/how-to-build-an-80-foot-wide-telescope-mirror-to-see-deep-space/

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