For every astronomical topic that I have approached there has turned out to be a broader realm of possibilities than is commonly accepted or acknowledged. The "excursions" of this book are the examples. They mostly depart from the mainstream of conventional wisdom to offer a wider perspective with opportunities for further research. While my intent is to supplement that mainstream, the effect may appear to dismiss rather than to reconsider accepted tenets. Ample praise and credit for those accomplishments are already available in textbooks. Readers may very well disagree with some of the...