Variations in the Brightness of Polaris

Over the past few decades there have been variations in the brightness of Polaris, the North Star. Around the 1990s, scientists realized that Polaris was becoming dimmer, only to increase in brightness again in the 2000s.

The variation in Polaris' brightness can be attributed to it belonging to a class of stars known as Cepheid variables, whose luminosity varies with time. Because the brightness of these Cepheids is directly related to the pulsation period, they serve an important function as standard candles that allow astronomers to measure distances in space.

Scott Engle, an astronomer at Villanova University, is part of a team that has been observing these fluctuations over the past years. Interestingly, in order to gauge how much brighter the North Star has become, they used data acquired by Tycho Brahe and dating as far back as the 10th century! Although not entirely accurate, they estimate that the start has become 2.5-4.6 times brighter!

Another interesting note is that even though Engle's team received approval to observe Polaris with the Hubble Space Telescope (HST), the HST team were reluctant because they feared that it might damage the sensitive Cosmic Origins Spectograph detector used in the telescope. Thankfully, nothing seems to have gone wrong.

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