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.

                               2025 January 31
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                        The Variable Nebula NGC 2261
      Image Credit & [3]Copyright: [4]Tommy Lease (Denver Astronomical
                                  Society)

   Explanation: The interstellar cloud of dust and gas captured in this
   sharp telescopic snapshot is seen to change its appearance noticeably
   over periods as short as a few weeks. Discovered over 200 years ago and
   cataloged as NGC 2261, bright star R Monocerotis lies at the tip of the
   fan-shaped nebula. About one light-year across and 2500 light-years
   away, [5]NGC 2261 was studied early last century by astronomer Edwin
   Hubble and the mysterious cosmic cloud is now more famous as Hubble's
   Variable Nebula. So what makes Hubble's nebula vary? NGC 2261 is
   composed of a dusty [6]reflection nebula fanning out from the star [7]R
   Monocerotis. The leading [8]variability explanation holds that dense
   knots of obscuring dust pass close to [9]R Mon and cast [10]moving
   shadows across the dust clouds in the rest of [11]Hubble's Variable
   Nebula.

                      Tomorrow's picture: light-weekend
     __________________________________________________________________

      [12]< | [13]Archive | [14]Submissions | [15]Index | [16]Search |
   [17]Calendar | [18]RSS | [19]Education | [20]About APOD | [21]Discuss |
                                    [22]>
     __________________________________________________________________

    Authors & editors: [23]Robert Nemiroff ([24]MTU) & [25]Jerry Bonnell
                                 ([26]UMCP)
          NASA Official: Amber Straughn [27]Specific rights apply.
              [28]NASA Web Privacy Policy and Important Notices
                A service of: [29]ASD at [30]NASA / [31]GSFC,
                         [32]NASA Science Activation
                           & [33]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/2501/HubblesVariablecopy.jpg
   3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
   4. https://www.instagram.com/colorado_astro/
   5. https://ui.adsabs.harvard.edu/abs/1916ApJ....44..190H/abstract
   6. https://apod.nasa.gov/apod/reflection_nebulae.html
   7. http://adsabs.harvard.edu/abs/1997ApJ...489..210C
   8. http://adsabs.harvard.edu/abs/1978ApJ...226..455A
   9. http://adsabs.harvard.edu/abs/1997ApJ...489..210C
  10. https://bigamateurtelescope.com/project/hubbles-variable-nebula/
  11. https://science.nasa.gov/mission/hubble/science/explore-the-night-sky/hubble-caldwell-catalog/caldwell-46/
  12. https://apod.nasa.gov/apod/ap250130.html
  13. https://apod.nasa.gov/apod/archivepix.html
  14. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  15. https://apod.nasa.gov/apod/lib/aptree.html
  16. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  17. https://apod.nasa.gov/apod/calendar/allyears.html
  18. https://apod.nasa.gov/apod.rss
  19. https://apod.nasa.gov/apod/lib/edlinks.html
  20. https://apod.nasa.gov/apod/lib/about_apod.html
  21. http://asterisk.apod.com/discuss_apod.php?date=250131
  22. https://apod.nasa.gov/apod/ap250201.html
  23. http://www.phy.mtu.edu/faculty/Nemiroff.html
  24. http://www.phy.mtu.edu/
  25. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  26. http://www.astro.umd.edu/
  27. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  28. https://www.nasa.gov/about/highlights/HP_Privacy.html
  29. https://astrophysics.gsfc.nasa.gov/
  30. https://www.nasa.gov/
  31. https://www.nasa.gov/centers/goddard/
  32. https://science.nasa.gov/learners
  33. http://www.mtu.edu/