It’s pretty easy to imagine carving glass to make parts for a piece of technology. We see them everyday–in eyeglasses, in microscopes in high school chemistry classes, and even in most telescopes. But astronomers have done something a bit different. They’ve made a telescope with a far weirder component: liquid mercury.
The International Liquid Mirror Telescope (ILMT), situated atop a mountain in the Himalayas, has a spinning vat of liquid mercury as its mirror. This international project—a collaboration between India, Belgium, Poland, Uzbekistan, and Canada—recently successfully observed its first supernova, illustrating that these fluid marvels can be used for modern astronomy. Their results are available on the pre-print server arXiv, and published in the Bulletin of the Liège Royal Society of Sciences.
“The ILMT is the first liquid mirror telescope designed specifically for astronomy and located at a good astronomical site,” explains Paul Hickson, co-author on the new work and astronomer at The University of British Columbia. In the past, NASA has used small liquid mirror telescopes (LMTs) to keep tabs on asteroids and other space debris, but these were generally in less desirable locations and smaller in size than the four-meter diameter ILMT.
The major telescopes of astronomy, like the James Webb Space Telescope or the Keck Observatory in Hawai’i, use humongous glass mirrors that have been carefully ground into a perfect parabola, the shape needed to focus light in a reflecting telescope. LMTs work by rotating a liquid—typically mercury—to make a parabola instead. Telescope operators have to keep careful tabs on the rotating fluid, as any tiny disturbances will blur their images.
Because they get around the tricky and time-consuming work of perfecting a glass behemoth, LMTs are often cheaper to make. However, they have one really significant drawback, which can be a dealbreaker for a lot of science cases. These…
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