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 October 4 [2]See Explanation. Clicking on the picture will download the highest resolution version available. InSight on a Cloudy Day Image Credit: [3]NASA, [4]JPL-Caltech, [5]Mars InSight Explanation: [6]Clouds drift through the sky as the light fades near sunset in this three frame animated gif. The scene was captured on sol 145 beginning around 6:30pm local time by a camera on the Mars InSight lander. Of course, InSight's martian day, sol 145, corresponds to Earth calendar date April 25, 2019. Under the 69 centimeter (2.3 foot) diameter dome in the foreground is the lander's sensitive [7]seismometer SEIS designed to detect marsquakes. Earthquakes reveal internal structures on planet Earth, and so tremors detected by SEIS can explore beneath the martian surface. In particular, two typical marsquakes were recorded by SEIS on [8]May 22 (sol 173) and [9]July 25 (sol 235). The subtle tremors from the Red Planet are at very low frequencies though, and for listening have to be processed into the audio frequency range. In the sped up recordings external noises more prevalent on cool martian evenings and likely caused by mechanical shifts and contractions have been technically [10]dubbed dinks and donks. Tomorrow's picture: moon shadow __________________________________________________________________ [11]< | [12]Archive | [13]Submissions | [14]Index | [15]Search | [16]Calendar | [17]RSS | [18]Education | [19]About APOD | [20]Discuss | [21]> __________________________________________________________________ Authors & editors: [22]Robert Nemiroff ([23]MTU) & [24]Jerry Bonnell ([25]UMCP) NASA Official: Phillip Newman [26]Specific rights apply. [27]NASA Web Privacy Policy and Important Notices A service of: [28]ASD at [29]NASA / [30]GSFC & [31]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/1910/PIA23180_raw.gif 3. https://www.nasa.gov/ 4. https://www.jpl.nasa.gov/ 5. https://mars.nasa.gov/insight/ 6. https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA23180 7. https://mars.nasa.gov/insight/spacecraft/instruments/seis/ 8. https://soundcloud.com/nasa/quake-sol-173 9. https://soundcloud.com/nasa/quake-sol-235 10. https://www.nasa.gov/feature/jpl/nasas-insight-hears-peculiar-sounds-on-mars 11. https://apod.nasa.gov/apod/ap191003.html 12. https://apod.nasa.gov/apod/archivepix.html 13. https://apod.nasa.gov/apod/lib/apsubmit2015.html 14. https://apod.nasa.gov/apod/lib/aptree.html 15. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 16. https://apod.nasa.gov/apod/calendar/allyears.html 17. https://apod.nasa.gov/apod.rss 18. https://apod.nasa.gov/apod/lib/edlinks.html 19. https://apod.nasa.gov/apod/lib/about_apod.html 20. http://asterisk.apod.com/discuss_apod.php?date=191004 21. https://apod.nasa.gov/apod/ap191005.html 22. http://www.phy.mtu.edu/faculty/Nemiroff.html 23. http://www.phy.mtu.edu/ 24. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 25. http://www.astro.umd.edu/ 26. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 27. https://www.nasa.gov/about/highlights/HP_Privacy.html 28. https://astrophysics.gsfc.nasa.gov/ 29. https://www.nasa.gov/ 30. https://www.nasa.gov/centers/goddard/ 31. http://www.mtu.edu/