The simplest questions are sometimes the hardest to answer. Why is the sky blue? Why is water wet? Why do we need sleep? Why are there 24 hours in a day? For each question, author Joel Levy provides a simple, single-line answer followed by more in-depth information about the scientific background on these essential topics. The book spans physics, biology, chemistry, geology, geography, meteorology, paleontology, and planetary science—allowing readers to wow friends and family alike with pithy answers to the obvious questions they never thought to ask.