Looking At The Stars Through a Puddle of Mercury

[JMAC]

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Popular Science
12/11/23

"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."

"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 unique telescopes can only point straight up (known as zenith pointing), as any tilting will disturb the spinning fluid with gravity. So unlike conventional telescopes, they can’t simply slew to any target in the sky—they’re fixed in place, and so have to wait for a target to pass overhead."



https://www.popsci.com/science/inter...ror-telescope/


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