As constant as the North Star?Jan 1, 2003
AS CONSTANT AS THE NORTH STAR? While Polaris has a laudable reputation as a celestial anchor, it doesn't win points for being one of the brighter stars in the sky. Recently, a group of researchers at the University of Toronto, led by Professor J. Donald Fernie, released a study suggesting Polaris has recently become even less of a standout.
Polaris is a variable star, belonging to a class of stars called cepheids that regularly fluctuate in brightness. A star can pulsate like this due to a buildup of internal pressure that causes it to expand and produce more light. Ultimately, however, the star cannot sustain this expansion and collapses back to its former size, becoming dimmer in the process.
Polaris had been on a regular schedule, exhibiting a 10% gain in brightness every four days. Now it seems that Polaris has departed from this schedule and its bright state is only 1% brighter than its dimmest level.
Even though it looks like Polaris is destined to remain a sighting challenge to the latitude-hungry navigator, at least northern types have a pole star; those in southerly latitudes are not so lucky.