Van Gogh's Starry Night Star Fishing Today I want to tell you about variable stars. They intrigue me because they change. They change in brightness. Some repeat cycles with almost clocklike precision others change irregularly. Some require only hours or days to return to their starting brightness. Others require years to change. Yet, whether they change imperceptibly or violently all variable stars change. The most spectacular variable is the Nova. It can get up to 200,000 times brighter than the Sun. But, alas, it is temporary. It periodically blows off a tiny percent of the Sun's mass at speeds up to 600 miles a second until it loses too much mass to continue. Whereas Supernovas brighten up to 10 billion times the Sun's brightness for a few days and then fade away forever. One more thing. Variable stars change their brightness by pulsating ever expanding and contracting like a balloon, They repeat their brightness cycles from one day to hundreds of … [Read more...]