Astronomers have discovered that Polaris, the north star, is getting brighter.
They say the star has suddenly reversed two decades of dimming.
It is expanding at more than 100 times the rate they expected – and nobody is sure why.
A team led by Scott Engle of Villanova University in Pennsylvania recalibrated historic measurements of Polaris by Ptolemy in 137 C.E., the Persian astronomer Al-Sufi in 964 C.E., and others.
They investigated the fluctuations of the star over the course of several years, combing through historical records and utilising the Hubble Space Telescope.
The team found that Polaris is 2.5 times brighter today than in Ptolemy’s time, which they say is a remarkable rate of change.