¿ Astronomy Picture of the Day [1]Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2021 April 28 [2]A picture of the the star Polaris surrounded by gas clouds and other stars. Please see the explanation for more detailed information. North Star: Polaris and Surrounding Dust Image Credit & Copyright: [3]Bray Falls Explanation: Why is Polaris called the North Star? First, [4]Polaris is the nearest [5]bright star toward the north [6]spin axis of the Earth. Therefore, as the Earth turns, stars appear to revolve around Polaris, but Polaris itself always stays in the same northerly direction -- making it the [7]North Star. Since no bright star is near the [8]south spin axis of the Earth, there is currently [9]no South Star. Thousands of years ago, Earth's spin axis pointed in a slightly different direction so that [10]Vega was the North Star. Although [11]Polaris is not the brightest star on the sky, it is easily located because it is [12]nearly aligned with two stars in the cup of the [13]Big Dipper. [14]Polaris is near the center of the eight-degree wide [15]featured image, an image that has been [16]digitally manipulated to suppress surrounding dim stars but accentuate the faint gas and dust of the [17]Intergalactic Flux Nebula (IFN). The surface of [18]Cepheid Polaris slowly [19]pulsates, causing the star to [20]change its brightness by a few percent over the course of a few days. Portal Universe: [21]Random APOD Generator Tomorrow's picture: open space __________________________________________________________________ [22]< | [23]Archive | [24]Submissions | [25]Index | [26]Search | [27]Calendar | [28]RSS | [29]Education | [30]About APOD | [31]Discuss | [32]> __________________________________________________________________ Authors & editors: [33]Robert Nemiroff ([34]MTU) & [35]Jerry Bonnell ([36]UMCP) NASA Official: Phillip Newman [37]Specific rights apply. [38]NASA Web Privacy Policy and Important Notices A service of: [39]ASD at [40]NASA / [41]GSFC & [42]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2104/Polaris_Falls_3543.jpg 3. https://www.instagram.com/astrofalls/ 4. https://en.wikipedia.org/wiki/Polaris 5. https://apod.nasa.gov/apod/ap190625.html 6. https://en.wikipedia.org/wiki/Axial_tilt#/media/File:AxialTiltObliquity.png 7. https://earthsky.org/brightest-stars/polaris-the-present-day-north-star 8. https://apod.nasa.gov/apod/ap210101.html 9. http://curious.astro.cornell.edu/our-solar-system/81-the-universe/stars-and-star-clusters/stargazing/374-is-there-a-south-star-intermediate 10. https://www.space.com/21719-vega.html 11. https://apod.nasa.gov/apod/ap150602.html 12. https://apod.nasa.gov/apod/ap201116.html 13. https://earthsky.org/favorite-star-patterns/big-and-little-dippers-highlight-northern-sky 14. https://upload.wikimedia.org/wikipedia/commons/c/cb/Ursa_Minor_IAU.svg 15. https://www.instagram.com/p/CNkySjvHTjx/?utm_source=ig_web_copy_link 16. https://i.pinimg.com/originals/07/9c/3e/079c3ea0dce59cc171629800294b0f3d.jpg 17. https://apod.nasa.gov/apod/ap170627.html 18. https://starchild.gsfc.nasa.gov/docs/StarChild/questions/cepheids.html 19. https://youtu.be/7ohkKiZTJOg 20. https://youtu.be/q-szkabhXQQ 21. https://apod.nasa.gov/apod/random_apod.html 22. https://apod.nasa.gov/apod/ap210427.html 23. https://apod.nasa.gov/apod/archivepix.html 24. https://apod.nasa.gov/apod/lib/apsubmit2015.html 25. https://apod.nasa.gov/apod/lib/aptree.html 26. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 27. https://apod.nasa.gov/apod/calendar/allyears.html 28. https://apod.nasa.gov/apod.rss 29. https://apod.nasa.gov/apod/lib/edlinks.html 30. https://apod.nasa.gov/apod/lib/about_apod.html 31. http://asterisk.apod.com/discuss_apod.php?date=210428 32. https://apod.nasa.gov/apod/ap210429.html 33. http://www.phy.mtu.edu/faculty/Nemiroff.html 34. http://www.phy.mtu.edu/ 35. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 36. http://www.astro.umd.edu/ 37. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 38. https://www.nasa.gov/about/highlights/HP_Privacy.html 39. https://astrophysics.gsfc.nasa.gov/ 40. https://www.nasa.gov/ 41. https://www.nasa.gov/centers/goddard/ 42. http://www.mtu.edu/