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. 2023 July 8 [2]See Explanation. Clicking on the picture will download the highest resolution version available. Stickney Crater Image Credit: [3]HiRISE, [4]MRO, [5]LPL (U. Arizona), [6]NASA Explanation: Stickney Crater, the largest crater on the martian moon Phobos, is named for [7]Chloe Angeline Stickney Hall, [8]mathematician and wife of astronomer Asaph Hall. Asaph Hall discovered both the [9]Red Planet's moons in 1877. Over 9 kilometers across, Stickney is nearly half the diameter of Phobos itself, so large that the impact that blasted out the crater likely came close to shattering the tiny moon. This [10]enhanced-color image of Stickney and surroundings was recorded by the HiRISE camera onboard the Mars Reconnaissance Orbiter as it passed within some six thousand kilometers [11]of Phobos in March of 2008. Even though the surface gravity of [12]asteroid-like Phobos is less than 1/1000th Earth's gravity, streaks suggest loose material slid down inside the crater walls over time. Light bluish regions near the crater's rim could indicate a relatively freshly exposed surface. The origin of the curious grooves along the surface is mysterious but may be related to tidal stresses experienced by [13]close-orbiting Phobos or [14]the crater-forming impact itself. Tomorrow's picture: doomed star __________________________________________________________________ [15]< | [16]Archive | [17]Submissions | [18]Index | [19]Search | [20]Calendar | [21]RSS | [22]Education | [23]About APOD | [24]Discuss | [25]> __________________________________________________________________ Authors & editors: [26]Robert Nemiroff ([27]MTU) & [28]Jerry Bonnell ([29]UMCP) NASA Official: Phillip Newman [30]Specific rights apply. [31]NASA Web Privacy Policy and Important Notices A service of: [32]ASD at [33]NASA / [34]GSFC & [35]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2307/PSP_007769_9010_IRB_Stickney.jpg 3. https://hirise.lpl.arizona.edu/ 4. https://mars.jpl.nasa.gov/mro/ 5. https://www.lpl.arizona.edu/ 6. https://www.nasa.gov/ 7. http://en.wikipedia.org/wiki/Angeline_Stickney 8. https://archive.org/details/anastronomerswi03hallgoog 9. https://apod.nasa.gov/apod/ap201030.html 10. http://hirise.lpl.arizona.edu/phobos.php 11. https://apod.nasa.gov/apod/ap170721.html 12. https://solarsystem.nasa.gov/moons/mars-moons/phobos/in-depth/ 13. https://apod.nasa.gov/apod/ap220703.html 14. http://adsabs.harvard.edu/abs/2016GeoRL..4310595B 15. https://apod.nasa.gov/apod/ap230707.html 16. https://apod.nasa.gov/apod/archivepix.html 17. https://apod.nasa.gov/apod/lib/apsubmit2015.html 18. https://apod.nasa.gov/apod/lib/aptree.html 19. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 20. https://apod.nasa.gov/apod/calendar/allyears.html 21. https://apod.nasa.gov/apod.rss 22. https://apod.nasa.gov/apod/lib/edlinks.html 23. https://apod.nasa.gov/apod/lib/about_apod.html 24. http://asterisk.apod.com/discuss_apod.php?date=230708 25. https://apod.nasa.gov/apod/ap230709.html 26. http://www.phy.mtu.edu/faculty/Nemiroff.html 27. http://www.phy.mtu.edu/ 28. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 29. http://www.astro.umd.edu/ 30. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 31. https://www.nasa.gov/about/highlights/HP_Privacy.html 32. https://astrophysics.gsfc.nasa.gov/ 33. https://www.nasa.gov/ 34. https://www.nasa.gov/centers/goddard/ 35. http://www.mtu.edu/