Future Outlook Astronomers anticipate that larger and larger ground-based
telescopes can be built in the future, using highly
computerized control systems to eliminate many of the constraints imposed by viewing through the Earth's atmosphere. Space-based telescopes, both in orbit and perhaps on the Moon, would provide other benefits and could also be linked by computer to Earth-based
instruments. Medium-size telescopes also continue to serve
important functions. Wide-field observations have been expanded by the recent combination of such instruments with charge-coupled device (CCD) detectors, the best targets being those with very low surface brightness and large angular extent. (Examples include the sodium "tails" extending from planets such as Jupiter.) Ground-based refractor telescopes remain in service for high-accuracy astrometry, because measurement of precise positions of celestial objects has important applications in analyzing the distribution and motion of mass in the universe.