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37211_Ward's World+MGH Telescope

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Telescope (continued) Modern astronomers essentially never use large telescopes for real-time, visual observations in the manner of the astronomers of previous centuries. Instead, researchers use telescopes to record volumes of data for future study and computer-driven analysis. Light received from most astronomical objects is made up of radiation of all wavelengths. The spectral characteristics of this radiation may be extracted by special instruments called spectrographs. Standard, solid-state detectors called charge- coupled devices (CCDs) or other imaging devices are used in conjunction with spectrographs to record spectral information. Photometry carried out with different filters yields basic infor- mation about the source with shorter observing time than that required for a complete spectroscopic analysis. The Earth's atmosphere limits the effectiveness of larger tele- scopes through image scintillation and motion, collectively known as poor seeing. However, adaptive optics allow ground- based telescopes to overcome blurriness and distortion caused by the atmospheric turbulence (Fig. 3). Techniques of interfer- + ward ' s science Fig. 2 A depiction of Galileo demonstrating the use of a telescope to a crowd in the 17th century. (Credit: Getty Images) Fig. 1 Multi-wavelength study of the core of the galaxy NGC 1512, revealing pockets of new star formation in both dust- obscured and clear regions. The Hubble Space Telescope obtained images of the galactic center in seven different wavelengths, from the ultraviolet to the infrared, shown in the boxes surrounding the centered, composite image. Wavelengths invisible to the human eye are assigned a representative color. These wavelengths are, clockwise from bottom left: 220 nm (ultraviolet); 328 nm (ultraviolet); 545 nm (visible); 659 nm (visible); 827 nm (infrared); 1600 nm (infrared); and 1870 nm (infrared). [Credit: NASA, ESA, Dan Maoz (Tel-Aviv University, Israel, and Columbia University, USA)] Fig. 3 At the European Southern Observatory's Very Large Telescope (VLT) in Chile, one of the four 8.2-m unit telescopes beams a high-powered laser as part of its adaptive optics system. [Credit: ESO/A. Ghizzi Panizza (www.albertoghizzipanizza.com)]

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