Finding the Speed of Light: The 1676 Discovery that Dazzled the World

Gr 3-5–Ole Rømer was a young Danish scientist in 1676 working for a French astronomer when he made the remarkable discovery that the appearance of light is not instantaneous; light actually moves and has a speed. It all started with his fascination with Io, one of Jupiter’s moons, and his observations that Io’s orbit seemed to slow down every now and then. Through careful and intricate math calculations, Rømer eventually realized that Io wasn’t slowing down; rather, the light from Io was taking longer to reach Earth because of its uneven orbit. This book includes a lot of text, and the narrative occasionally meanders, making it confusing to follow. Speech bubbles sometimes complement the story of Rømer and the scientists with whom he worked, and sometimes focus on facts or explanations, adding to the inconsistent feel. Descriptions of scientific and mathematical concepts are detailed and fairly complicated. The lovely watercolors are full of washes of blues and deep purples, fitting the subject. Back matter includes a brief time line and an afterword that extends some of the ideas from the book, but there is no bibliography or further reading list.