Polaris Brightening

Polaris has been the North Star for thousands of years, but for the past few centuries it's been getting brighter.

Astronomers have known for roughly one century that Polaris is a Cepheid variable.  It pulses in brightness over a cycle.  Using both current and historical data, however, a team has determined that Polaris is brighter now than it was centuries ago, and that it continues to brighten.  So do other Cepheids.  Since Cepheids are used to determine distances in the universe based on their reliability, understanding the unexpected brightening is important.