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 December 14
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                        Interstellar Comet 2I/Borisov
      Image Credit: [3]NASA, [4]ESA, and [5]D. Jewitt ([6]UCLA) et al.

   Explanation: [7]From somewhere else in the Milky Way galaxy, [8]Comet
   2I/Borisov is just visiting the Solar System. Discovered by Crimean
   amateur astronomer Gennady Borisov on August 30, 2019, the first known
   interstellar comet is captured in these two recent [9]Hubble Space
   Telescope images. On the left, a distant background galaxy near the
   line-of-sight to Borisov is blurred as [10]Hubble tracked the speeding
   comet and dust tail about 327 million kilometers from Earth. At right,
   2I/Borisov appears shortly after perihelion, it's closest approach to
   Sun. Borisov's closest approach to our fair planet, a distance of about
   290 million kilometers, will come on December 28. Even though Hubble's
   sharp images don't resolve the comet's nucleus, they do lead to
   estimates of less than 1 kilometer for its diameter.

                       Tomorrow's picture: cloudy day
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    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/1912/borisovStsci1826.jpg
   3. https://www.nasa.gov/
   4. http://www.spacetelescope.org/
   5. http://www2.ess.ucla.edu/~jewitt/David_Jewitt.html
   6. http://www.ess.ucla.edu/
   7. https://apod.nasa.gov/apod/ap191018.html
   8. https://en.wikipedia.org/wiki/2I/Borisov
   9. https://hubblesite.org/contents/news-releases/2019/news-2019-61
  10. https://hubblesite.org/contents/media/videos/2019/53/1244-Video
  11. https://apod.nasa.gov/apod/ap191213.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=191214
  21. https://apod.nasa.gov/apod/ap191215.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/