The sky we see is always changing. The Sun, Moon, planets, and stars rise and set each day as the Earth rotates. They also change their relative positions in the sky depending on the time of the month or year. We can predict their motions and know where to look. Less frequently, but just as predictably, are the changes of season, meteor showers, and eclipses. And comets appear periodically, some right on schedule, some for the first time. For each object, you can check when to observe.