A、To overcome the problem of weak light. B、To take more photographs. C、To photograph astronomical objects without using a telesc

Most people think of astronomers as people who spend their time in cold observatories peering through telescope every night. In fact, a typical, astronomer spends most of his or her time analyzing data and may only be at the telescope a few weeks of the year. Some astronomers work on purely theoretical problems and never use a telescope at all. You night not know how rarely images are viewed directly through telescopes. The most common way to observe the skies is to photograph them. The process is very simple. First, a photographic plate is coated with a lightsensitive material. The plate is positioned so that the image received by the telescope is recorded on it. Then, the image cam he developed, enlarged and published so that many people can study it. Because most astronomical objects are very remote, the light we receive from them is rather feeble. But by using a telescope as a camera, long time exposures can be made. In this way objects can be photographed that are a hundred times tm faint to be seen by just looking through a telescope.