Reflections on Space: Liquid Mirror Telescopes in Beyond Planet Earth

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Many scientists' vision of a Moon colony includes a liquid mirror telescope, which appears in the background of this image. © AMNH/M. Garlick

Imagine a mirror as wide as a football field at the South Pole of the Moon. Instead of polished glass, its surface is made of a reflective liquid, which spins in a circle.

Scientists hope to make this vision a reality one day by using a liquid mirror to build a giant lunar telescope that would allow astronomers to see farther into the universe than ever before. In the Museum’s special exhibition Beyond Planet Earth: The Future of Space Exploration, visitors can see two liquid mirror telescopes: one featured as part of a Moonscape diorama, the other, an interactive model that can be operated with the push of a button.

When a liquid spins, it forms a parabolic shape similar to the curve of the mirror on a traditional telescope. A liquid mirror telescope exploits this property to make a surface that, when rotated at constant speed, resembles a gently arched solid. This type of telescope would be easier and lighter to carry through space because the liquid could be stored in a vat for the journey to the Moon, and the overall cost and maintenance would be astronomically lower than conventional instruments because it would not need constant adjustment or cleaning.

While mercury-based liquid mirror telescopes already exist on Earth, astrophysicist Mike Shara, curator of Beyond Planet Earth, says building one on the Moon would allow astronomers to take this technology to the next level. “On the Moon, there’s no atmosphere,” explains Dr. Shara. “Wind wouldn’t ripple the surface of the liquid, and every night would be cloudless, giving the clearest views of deep space. A large enough liquid mirror telescope on the Moon would allow you to image the continents on distant planets.”

Beyond Planet Earth: The Future of Space Exploration opens November 19. Click here to buy tickets.