Amateur astronomers and astrophotographers must understand how to find the North Star to align their telescopes. This is referred to as polar alignment and it is a critical step of the process when using an equatorial telescope mount. That was until recent observations uncovered 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. a b c d Lee, B. C.; Mkrtichian, D. E.; Han, I.; Park, M. G.; Kim, K. M. (2008). "Precise Radial Velocities of Polaris: Detection of Amplitude Growth". The Astronomical Journal. 135 (6): 2240. arXiv: 0804.2793. Bibcode: 2008AJ....135.2240L. doi: 10.1088/0004-6256/135/6/2240. S2CID 12176373. Liu, C.; Bailer-Jones, C. A. L.; Sordo, R.; Vallenari, A.; etal. (2012). "The expected performance of stellar parametrization with Gaia spectrophotometry". Monthly Notices of the Royal Astronomical Society. 426 (3): 2463. arXiv: 1207.6005. Bibcode: 2012MNRAS.426.2463L. doi: 10.1111/j.1365-2966.2012.21797.x. S2CID 1841271.

a b Bailer-Jones, C. A. L; Rybizki, J; Fouesneau, M; Mantelet, G; Andrae, R (2018). "Estimating Distance from Parallaxes. IV. Distances to 1.33 Billion Stars in Gaia Data Release 2". The Astronomical Journal. 156 (2): 58. arXiv: 1804.10121. Bibcode: 2018AJ....156...58B. doi: 10.3847/1538-3881/aacb21. S2CID 119289017. What’s more, since it’s so close to the north celestial pole, Polaris always at the same altitude above the horizon as your latitude. This is a smart, sophisticated, topical spy story hard to put down…I highly recommend this book for anyone longing to know more about this shadowy nation and its secretive regime.”– The Missourian Cepheid variable stars can be used to measure the distance to galaxies and the expansion rate of the universe. This is why it is so important to understand their physics and evolution.

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By the way, Polaris is famous for more reasons than one. It’s famous for hardly moving while the other stars wheel around it. And it’s famous for marking the end of the Little Dipper‘s handle. The Little Dipper is tougher to spot in the night sky than the Big Dipper. But if you use the Big Dipper’s pointer stars to locate Polaris, you’ll be one step closer to seeing the Little Dipper. The Big Dipper leads you to the Little Dipper. Polaris marks the end of the handle of the Little Dipper. Its height in the sky depends on your location Meanwhile, where I live Polaris is lower, around 41 degrees from the horizon. How to find Polaris, the North Star The Plough asterism. Credit: Bernhard Hubl / CCDGuide.com Star of The North reads like a cross between Child-44 and I am Pilgrim and is every bit as good as both of them. Read this book and you will not only feel that you've been to North Korea you will also never, ever want to go there. Brutally realistic, fascinatingly detailed, it's a fantastic thriller whose fantasy is all the more powerful for being based on truth. Simon Toyne, bestselling author of the Sanctus trilogy and Solomon Creed series This means they’re so far to the north that they don’t rise and set as other stars do, and they don’t come and go with the seasons. Astronomers estimate Polaris’ distance at 434 light-years. Considering the distance, Polaris must be a respectably luminous star. Polaris is a yellow supergiant star shining with the luminosity of 1,260 suns. And it varies in brightness, too!

Irion, R (2004). "American Astronomical Society meeting. As inconstant as the Northern Star". Science. 304 (5678): 1740–1. doi: 10.1126/science.304.5678.1740b. PMID 15205508. S2CID 129246155. As the closest Cepheid variable its distance is used as part of the cosmic distance ladder. The revised Hipparcos stellar parallax gives a distance to Polaris of about 433 light-years (133 parsecs), while the successor mission Gaia gives a distance of about 448 light-years (137 parsecs). Calculations by other methods vary widely. Once we’ve found the Plough, all we need to do is draw a line between Merak (β UMa) and Dubhe (α UMa), the two stars at the end of the Plough’s blade, and then out through the blade’s top.The next fairly bright star we see is Polaris.a b Neilson, H. R.; Engle, S. G.; Guinan, E.; Langer, N.; Wasatonic, R. P.; Williams, D. B. (2012). "The Period Change of the Cepheid Polaris Suggests Enhanced Mass Loss". The Astrophysical Journal. 745 (2): L32. arXiv: 1201.0761. Bibcode: 2012ApJ...745L..32N. doi: 10.1088/2041-8205/745/2/L32. S2CID 118625176.

The single point of light that we see as Polaris is a triple star system, or three stars orbiting a common center of mass. The primary star, Polaris A, is a supergiant with about six times the mass of our sun. A close companion, Polaris Ab, orbits 2 billion miles from Polaris. You are unlikely to ever see this star, because it is too close to Polaris. Cassoipeia, Cepheus, Dracoand objects in that part of the sky are also all circumpolar, and it’s exciting to show people who are new to the skies how to find those, too. Merak and Dubhe are also known as the 'Pointers', because they point to Polaris, the North Star. al-Raḥmān ibn ʻUmar Ṣūfī (1874). Description des Etoiles fixes. Commissionnaires de lÁcadémie Impériale des sciences. p.45. Cayrel de Strobel, G.; Soubiran, C.; Ralite, N. (2001). "Catalogue of [Fe/H] determinations for FGK stars: 2001 edition". Astronomy and Astrophysics. 373: 159–163. arXiv: astro-ph/0106438. Bibcode: 2001A&A...373..159C. doi: 10.1051/0004-6361:20010525. S2CID 17519049. In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN) [41] to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 [42] included a table of the first two batches of names approved by the WGSN; which included Polaris for the star α Ursae Minoris Aa.The Hipparcos spacecraft used stellar parallax to take measurements from 1989 and 1993 with the accuracy of 0.97 milliarcseconds (970 microarcseconds), and it obtained accurate measurements for stellar distances up to 1,000pc away. [58] The Hipparcos data was examined again with more advanced error correction and statistical techniques. [2] Despite the advantages of Hipparcos astrometry, the uncertainty in its Polaris data has been pointed out and some researchers have questioned the accuracy of Hipparcos when measuring binary Cepheids like Polaris. [9] The Hipparcos reduction specifically for Polaris has been re-examined and reaffirmed but there is still not widespread agreement about the distance. [59]

a b c d e f g h i Usenko, I. A.; Klochkova, V. G. (2008). "Polaris B, an optical companion of the Polaris (α UMi) system: Atmospheric parameters, chemical composition, distance and mass". Monthly Notices of the Royal Astronomical Society: Letters. 387 (1): L1. arXiv: 0708.0333. Bibcode: 2008MNRAS.387L...1U. doi: 10.1111/j.1745-3933.2008.00426.x. S2CID 18848139.It’s a good plot, greatly enriched by the portrait of the totalitarian society that John draws Marcel Berlins, The Times Star of the North is one to look out for when it’s published in early May. Original, cleverly plotted and easy to read. After a brilliant set up it’s action all the way to the finish. As the strands of the story come together the plot reaches a nail biting and powerful conclusion.” - Nudge-Book.com, http://nudge-book.com/blog/2018/02/star-of-the-north-by-d-b-john/ Star trails shown circling around Polaris, the North Star. Image via Goodfreephotos.com/ Unsplash. Used with permission. Don’t wait for it to set The primary star, Polaris A, is a supergiant more than two thousand times brighter than our sun. The next closest companion is Polaris Ab, a main-sequence star. A) The idea started to take shape in December 2011 when I saw the news footage from the streets of Pyongyang shortly after Kim Jong-il’s death was announced. People were crying and wailing, prostrating themselves on the snow, appealing the sky with their hands. It was as if they were under a spell. There was something desperate about the grieving, too, as if they knew that punishment awaited those who shed too few tears. This was the world’s last remaining totalitarian tyranny, where the rules of human behavior, I realized, were different. It made me want to know about the inner lives of North Koreans, and I started to wonder what it would be like to depict them in private, without the masks they wore in public.