Supersizing The Heavens

摘要

Space-based observatories have much to recommend them; they, see in wavelengths forever hidden from observers on Earth's surface, and with the crystal clarity of an airless sky. But they are hard put to compete in one of the most important aspects of telescope design: size. Whether you want a telescope for a backyard or a mountain top, the larger the light-gathering surface, the more photons you will catch. With a primary mirror measuring 42 metres across, the European Extremely Large Telescope (E-ELT) is designed to pick out features only hinted at in the best images made by orbiting telescopes, detecting objects as faint as the planets around other stars.