Light and Time

Light is electromagnetic radiation that travels in waves, enabling us to see and carry information across distances, such as from the Sun to Earth. It moves at an incredible speed—about 186,282 miles per second—meaning electromagnetic signals, including light, take time to reach us from distant objects. Time is a measure of the sequence and duration of events, providing a framework to understand change and motion. Understanding that light takes time to travel helps us realize that observing distant stars and galaxies shows us their past, as their light takes years or even millions of years to reach us, linking light and time in the fabric of the universe.