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 July 22
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                  HDR: Earth's Circular Shadow on the Moon
              Image Credit & Copyright: [3]Cristian Fattinnanzi

   Explanation: What could create such a large circular shadow on the
   Moon? The Earth. Last week's full Moon -- the [4]Buck Moon -- was so
   full that it fell almost exactly [5]in a line with the [6]Sun and the
   [7]Earth. When that happens the Earth casts its [8]shadow onto the
   Moon. The circularity of the Earth's shadow on the Moon was commented
   on by [9]Aristotle and so has [10]been noticed since at least the
   [11]4th century BC. What's new is humanity's ability to record [12]this
   shadow with such [13]high dynamic range (HDR). The featured HDR
   composite of last week's partial [14]lunar eclipse combines 15 images
   and include an exposure as short as 1/400th of a second -- so as not to
   overexpose the brightest part -- and an exposure that lasted five
   seconds -- to bring up the dimmest part. This dimmest part -- inside
   [15]Earth's umbra -- is [16]not completely dark because some [17]light
   is refracted through the [18]Earth's atmosphere [19]onto the Moon. A
   [20]total lunar eclipse will [21]occur next in 2021 May.

   Partial Lunar Eclipse in 2019 July: [22]Some memorable images submitted
                                   to APOD
                 Tomorrow's picture: extragalactic ejection
     __________________________________________________________________

      [23]< | [24]Archive | [25]Submissions | [26]Index | [27]Search |
   [28]Calendar | [29]RSS | [30]Education | [31]About APOD | [32]Discuss |
                                    [33]>
     __________________________________________________________________

    Authors & editors: [34]Robert Nemiroff ([35]MTU) & [36]Jerry Bonnell
                                 ([37]UMCP)
          NASA Official: Phillip Newman [38]Specific rights apply.
              [39]NASA Web Privacy Policy and Important Notices
                A service of: [40]ASD at [41]NASA / [42]GSFC
                           & [43]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/1907/PartialLunarEclipse_Fattinnanzi_3345.jpg
   3. http://www.cristianfattinnanzi.it/
   4. https://www.timeanddate.com/astronomy/moon/buck.html
   5. https://sservi.nasa.gov/articles/eclipse-perspective-what-would-an-astronaut-see-from-the-moon/
   6. https://solarsystem.nasa.gov/solar-system/sun/overview/
   7. https://solarsystem.nasa.gov/planets/earth/overview/
   8. https://apod.nasa.gov/apod/ap130524.html
   9. https://en.wikipedia.org/wiki/Aristotle
  10. https://www.aps.org/publications/apsnews/200606/history.cfm
  11. https://en.wikipedia.org/wiki/4th_century_BC
  12. https://apod.nasa.gov/apod/ap190718.html
  13. https://en.wikipedia.org/wiki/High-dynamic-range_imaging
  14. https://eclipse.gsfc.nasa.gov/lunar.html
  15. https://apod.nasa.gov/apod/ap190126.html
  16. https://ameliacarruthers.files.wordpress.com/2015/01/black-cat-in-a-dark-room-there-is-nothing-harder.png
  17. https://earthsky.org/space/why-does-the-moon-look-red-during-a-total-lunar-eclipse
  18. https://apod.nasa.gov/apod/ap140803.html
  19. https://apod.nasa.gov/apod/ap190717.html
  20. https://apod.nasa.gov/apod/ap190120.html
  21. https://eclipse.gsfc.nasa.gov/LEdecade/LEdecade2021.html
  22. https://www.facebook.com/pg/APOD.Sky/photos/?tab=album&album_id=2009822242455318
  23. https://apod.nasa.gov/apod/ap190721.html
  24. https://apod.nasa.gov/apod/archivepix.html
  25. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  26. https://apod.nasa.gov/apod/lib/aptree.html
  27. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  28. https://apod.nasa.gov/apod/calendar/allyears.html
  29. https://apod.nasa.gov/apod.rss
  30. https://apod.nasa.gov/apod/lib/edlinks.html
  31. https://apod.nasa.gov/apod/lib/about_apod.html
  32. http://asterisk.apod.com/discuss_apod.php?date=190722
  33. https://apod.nasa.gov/apod/ap190723.html
  34. http://www.phy.mtu.edu/faculty/Nemiroff.html
  35. http://www.phy.mtu.edu/
  36. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  37. http://www.astro.umd.edu/
  38. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  39. https://www.nasa.gov/about/highlights/HP_Privacy.html
  40. https://astrophysics.gsfc.nasa.gov/
  41. https://www.nasa.gov/
  42. https://www.nasa.gov/centers/goddard/
  43. http://www.mtu.edu/