The great gravitational attractor holds together a system of 17 major planets and dwarf planets and their moons, asteroids, meteoroids, comets, and even the remote Oort cloud. It is its gravity that holds us captive in an orbit that is not too hot and not too cold. It is indeed central to our lives—the source of daylight, the driver of the planet’s winds and ocean currents, the source of energy for our activities, and for our food itself. Some past cultures have recognized its importance and have considered the Sun to be worthy of worship. Now we think that it is worthy of study, to learn about its light, its surface, and its magnetism and to apply what we know about matter and energy, to understand processes within.