AUSTIN, TEXAS — Astronomers from The University of Texas at Austin have revived a plan to build a massive 100-meter wide mirror — made of liquid — on the surface of the moon. <br /><br />The scientists described the importance of such a huge project in a new paper published in The Astrophysical Journal. <br /><br />They say a giant moon-based telescope would be able to capture light from objects nearly as old as the Big Bang. <br /><br />Liquid mirrors are lighter, simpler, faster to construct, and ten times cheaper than conventional glass telescope mirrors. <br /><br />The key to a liquid mirror telescope is that the liquid must be rotated constantly. <br /><br />When the liquid rotates, gravity pulls down on its surface, while inertia pulls it sideways at the edge of the dish. <br /><br />As a result, the liquid forms a uniform and perfect parabola, the ideal reflecting surface for a telescope. <br /><br />Work is underway to find the perfect mix of liquids, as it requires a liquid metal to drift on top of other liquids, plus a thin layer of material on top to minimize evaporation. <br /><br />Liquid mirrors usually use mercury, but that won't work on the moon, as mercury will freeze in the very cold moon temperatures.
