[Journal of SPIE]. More photons, he says, basically means more science about incredibly faint, distant objects. I began building it in the spring of 2008, but the bulk of the work was done in July of 2008 with first light occurring on July 25. It's subject to tarnish, and oxidation, and corrosion.". The technique allows them to take a silver-coated mirror—and coat it with extremely uniform layers of transparent aluminum oxide, to protect against corrosion. Building a mirror for any giant telescope is no simple feat. "We in astronomy are always greedy. Take a plastic bottle (from drinks etc) 0.5 liters, add a few spoons of grit in the bottle and add 6-8 times the volume of water. Scientific American is part of Springer Nature, which owns or has commercial relations with thousands of scientific publications (many of them can be found at, More reflective telescope mirrors allow astronomers to capture more photons. And that's where the optics problem comes in. To compute the power or magnification (M) of your telescope, you will use the focal lengths computed in the experiment named, "Focusing Light With a Lens," page 49 in the Educator Guide: Optics - Light, Color and their Uses.Insert the number for each previously computed focal length into the following equation: ", So you want the most reflective material for your mirrors. —and coat it with extremely uniform layers of transparent aluminum oxide, to protect against corrosion. Shake well before pouring the grit on the mirror. Building a reflector telescope can be decomposed in 2 steps: make the mirror and build the tube/mount. Casting a $20 Million Mirror for the World’s Largest Telescope The traditional mirror coating, aluminum, reflects only about 90 percent of light. Santa Cruz, —is scaled up to coat mirror segments up to a meter in diameter. When put to use, these better mirrors might allow astronomers to capture more photons… and shed more light—literally—on faraway galaxies and stars. After a pause for work on two other mirrors, the lab is in the process of grinding Segments 2 and 3. In this post, we’ll talk about the first one which is the most time consuming but also the most interesting. Subscribers get more award-winning coverage of advances in science & technology. Here at the Mirror Lab, we finished making the first Giant Magellan Telescope segment in 2012. Like silver, which reflects 97 to 99 percent of visible and infrared light, respectively. Its what I decided to use to make the mirror. Big improvement over aluminum. Bounce that light around a few times in a telescope, and you lose valuable photons. We want every photon we can collect." And mirrors aren't perfectly reflective. —and do more science. But silver's got problems too. It was 40"x40" and 0.75" thick. This Instructable describe the planning, design, and par… 60-Second Science - 0 minute ago - By Christopher Intagliata, 60-Second Science - 20 hours ago - By Susanne Bard, 60-Second Science - November 18, 2020 - By Christopher Intagliata, 60-Second Science - November 17, 2020 - By Scott Hershberger, Divide and Conquer Could Be Good COVID Strategy, 60-Second Science - November 12, 2020 - By W. Wayt Gibbs, 60-Second Science - November 10, 2020 - By Mark Stratton, Funky Cheese Rinds Release an Influential Stench. The traditional mirror coating, aluminum, reflects only about 90 percent of light. Bounce that light around a few times in a telescope, and you lose valuable photons. "It is finicky. Observations, Data, and Conclusions. ], Scientific American Space & Physics is a roundup of the most important stories about the universe and beyond. Meaning you could coat all 500 mirrors of a state-of-the-art telescope—like the planned Thirty Meter Telescope—in a matter of months. It starts to look like a telescope mirror :) The #400 grit is the finest size you will add with the teaspoon. The technique allows them to take a silver-coated mirror. "The throughput, the actual number of photons that are detected in the end in a modern spectrograph, you're doing good if you get thirty percent. Finer than that, they need to be premixed with water.