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. 2019 November 30 [2]See Explanation. Clicking on the picture will download the highest resolution version available. Star Trails for a Red Planet Image Credit & [3]Copyright: [4]Dengyi Huang Explanation: [5]Does Mars have a north star? In long exposures of [6]Earth's night sky, star trails make concentric arcs around the north celestial pole, the direction of our fair planet's [7]axis of rotation. [8]Bright star Polaris is presently the Earth's North Star, close on the sky to Earth's north celestial pole. But long exposures on [9]Mars show star trails too, concentric arcs about a celestial pole determined by Mars' axis of rotation. Tilted like planet Earth's, the martian axis of rotation points in a different direction in space though. [10]It points to a place on the sky between stars in Cygnus and Cepheus with no bright star comparable to Earth's north star Polaris nearby. So even though this ruddy, weathered landscape is [11]remarkably reminiscent of terrain in images from the [12]martian surface, the view must be from planet Earth, with north star Polaris near the center of concentric star trails. The landforms in the foreground are found in Qinghai Province in [13]northwestern China. Tomorrow's picture: blue starburst __________________________________________________________________ [14]< | [15]Archive | [16]Submissions | [17]Index | [18]Search | [19]Calendar | [20]RSS | [21]Education | [22]About APOD | [23]Discuss | [24]> __________________________________________________________________ Authors & editors: [25]Robert Nemiroff ([26]MTU) & [27]Jerry Bonnell ([28]UMCP) NASA Official: Phillip Newman [29]Specific rights apply. [30]NASA Web Privacy Policy and Important Notices A service of: [31]ASD at [32]NASA / [33]GSFC & [34]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/1911/StarTrailsOnRedPlanet2048.jpg 3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 4. mailto: huang dengyi [at] 126 [dot] com 5. https://earthsky.org/astronomy-essentials/mars-north-south-star 6. https://apod.nasa.gov/apod/ap131023.html 7. https://apod.nasa.gov/apod/ap070519.html 8. https://apod.nasa.gov/apod/ap110514.html 9. https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA03615 10. https://en.wikipedia.org/wiki/Astronomy_on_Mars#Celestial_poles_and_ecliptic 11. https://en.wikipedia.org/wiki/Yardangs_on_Mars 12. https://phys.org/news/2019-04-small-china-mars-base-teens.html 13. https://en.wikipedia.org/wiki/Dunhuang_Yardang_National_Geopark 14. https://apod.nasa.gov/apod/ap191129.html 15. https://apod.nasa.gov/apod/archivepix.html 16. https://apod.nasa.gov/apod/lib/apsubmit2015.html 17. https://apod.nasa.gov/apod/lib/aptree.html 18. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 19. https://apod.nasa.gov/apod/calendar/allyears.html 20. https://apod.nasa.gov/apod.rss 21. https://apod.nasa.gov/apod/lib/edlinks.html 22. https://apod.nasa.gov/apod/lib/about_apod.html 23. http://asterisk.apod.com/discuss_apod.php?date=191130 24. https://apod.nasa.gov/apod/ap191201.html 25. http://www.phy.mtu.edu/faculty/Nemiroff.html 26. http://www.phy.mtu.edu/ 27. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 28. http://www.astro.umd.edu/ 29. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 30. https://www.nasa.gov/about/highlights/HP_Privacy.html 31. https://astrophysics.gsfc.nasa.gov/ 32. https://www.nasa.gov/ 33. https://www.nasa.gov/centers/goddard/ 34. http://www.mtu.edu/