variable star

A variable star is a type of star whose brightness changes over time. This fluctuation can occur over short periods, like hours or days, or over much longer timescales. The variations in brightness can be caused by different factors, such as changes in the star’s size, temperature, or position in relation to Earth. Some variable stars regularly pulse in brightness, while others may have irregular changes. Astronomers study these stars to learn more about stellar life cycles and the processes occurring within and around them.