Sun, Earth and Sky

This book was written for my daughter, Julia; her love and comfort have helped sustain me. It is a pleasure to watch Julia noticing details of every- thing around her. Children and other curious people perceive worlds that are invisible to most of us. Here we describe some of these natural unseen worlds, from the hid- den heart of the Sun to our transparent air. They have been discovered and explored through the space-age extension of our senses. A mere half-century ago astronomers were able to view the cosmos only in visible light. Modern technology has now widened the range of our perception to include the invisible realms of subatomic particles, magnetic fields, radio waves, ultraviolet radiation and X-rays. They are broadening and sharpening our vision of the Sun, and providing a more complete description of the Earth's environment. Thus, a marvelous new cosmos is now unfolding and opening up, as new instruments give us the eyes to see the invisible and hands to touch what cannot be felt.