Hidden Universe Uncovered

摘要

To the human eye, the night sky is a canopy of stars. With the aid of a small telescope it is possible to see our nearest Galactic neighbours, and using sensitive charge-coupled detectors and the worlds largest optical telescopes we can go beyond this and peer into the farthest reaches of the Universe. However, even the most sensitive of these visible-light surveys miss much of the light emitted by galaxies over the history of the Universe. This missing light comes from the youngest stars, which are still cocooned in their natal dust clouds. Dust clouds absorb starlight and re-emit it at far-infrared wavelengths. Surveys of the sky in the far-infrared and the longer-wavelength submillimetre wavebands are thus essential if we are to obtain a complete picture of the star-formation history of galaxies, and hence to identify more precisely the epoch at which galaxies such as our own formed.