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Inconstant north star

Posted: Sat Apr 29, 2023 8:11 pm
by JimCunn
It is well known that Polaris (the north star) is a Cepheid variable, but its periodic brightness variations have been steadily decreasing in amplitude for the last hundred years. Around the beginning of the 20th Century, Polaris’ brightness fluctuated every four days by 10%. Only ten years ago this variation had dropped to 2%, but recent observations display an increase in variability to 4%. Polaris is an odd star in that it is a Cephid variable with a declining variability, and now astronomers are baffled as to why the brightness fluctuation has been revived…

Oh well, in only 13,000 years Thuban will be the north star, so it's only a temporary thing.... 😉

Re: Inconstant north star

Posted: Sun Apr 30, 2023 10:48 am
by North Country Gal
And if you go back far enough in time, Thuban was the north star then, too.

Re: Inconstant north star

Posted: Mon May 08, 2023 1:02 pm
by JimCunn
Yup. About 13,000 years in either direction 😉