When stars are viewed on a human timescale, they appear to never change
During one of my recent night sky tours, an elderly guest gazed into the sky and asked if the stars ever move. He said the constellations look the same now as when he was a child, and he was convinced that nothing in the heavens ever changes. It was an excellent observation but one that didn’t consider an important fact: Human time scales are considerably different than cosmic time scales. Even the healthiest of humans will live at most about a century, and during our lives, we measure time in seconds, minutes, hours, days, weeks, months, years and decades. The cosmos, on the other ...