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 September 7 [2]See Explanation. Clicking on the picture will download the highest resolution version available. In Wolf's Cave Image Credit & [3]Copyright: [4]Charlie Bracken, Mladen Dugec, Max Whitby Explanation: [5]The mysterious blue reflection nebula found in catalogs as VdB 152 or Ced 201 really is very faint. It lies at the tip of the long [6]dark nebula Barnard 175 in a dusty complex that has also been called [7]Wolf's Cave. At the center of this deep and widefield telescopic view, the cosmic apparitions are nearly 1,400 light-years away along the northern Milky Way in the [8]royal constellation Cepheus. Near the edge of a large molecular cloud, pockets of interstellar dust in the region block light from background stars or scatter light from the embedded bright star giving the the nebula its characteristic blue color. Ultraviolet light from the star is also [9]thought to cause a dim reddish luminescence in the nebular dust. Though stars do form in [10]molecular clouds, this star seems to have only accidentally wandered into the area, as its measured velocity through space is very different from the cloud's velocity. Another dense, obscuring dark nebula, LDN 1221, is easy to spot at the upper right in the frame, while the more colorful planetary nebula [11]Dengel-Hartl 5 is just below center. Faint reddish emission from an ancient supernova remnant [12]can also be traced (lower right to upper left) against the dust-rich complex in Cepheus. Tomorrow's picture: perijove 11 __________________________________________________________________ [13]< | [14]Archive | [15]Submissions | [16]Index | [17]Search | [18]Calendar | [19]RSS | [20]Education | [21]About APOD | [22]Discuss | [23]> __________________________________________________________________ Authors & editors: [24]Robert Nemiroff ([25]MTU) & [26]Jerry Bonnell ([27]UMCP) NASA Official: Phillip Newman [28]Specific rights apply. [29]NASA Web Privacy Policy and Important Notices A service of: [30]ASD at [31]NASA / [32]GSFC & [33]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/1909/WolfsCaveCBMDMW.jpg 3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 4. https://digitalstars.wordpress.com/ 5. https://ui.adsabs.harvard.edu/abs/1908MNRAS..69..117W/abstract 6. https://apod.nasa.gov/apod/ap090425.html 7. https://www.universetoday.com/17215/the-cepheus-flare-lights-the-entrance-to-wolfs-cave-cederblad-201-and-van-den-bergh-152-by-kent-wood/ 8. https://earthsky.org/sky-archive/constellation-cepheus-looks-like-a-house 9. https://ui.adsabs.harvard.edu/abs/1985ApJ...294..225W/abstract 10. http://coolcosmos.ipac.caltech.edu/cosmic_classroom/cosmic_reference/molecular_clouds.html 11. https://astrodonimaging.com/gallery/dengel-hartl-5-in-cepheus/ 12. http://bf-astro.com/vdB152/vdB152.htm 13. https://apod.nasa.gov/apod/ap190906.html 14. https://apod.nasa.gov/apod/archivepix.html 15. https://apod.nasa.gov/apod/lib/apsubmit2015.html 16. https://apod.nasa.gov/apod/lib/aptree.html 17. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 18. https://apod.nasa.gov/apod/calendar/allyears.html 19. https://apod.nasa.gov/apod.rss 20. https://apod.nasa.gov/apod/lib/edlinks.html 21. https://apod.nasa.gov/apod/lib/about_apod.html 22. http://asterisk.apod.com/discuss_apod.php?date=190907 23. https://apod.nasa.gov/apod/ap190908.html 24. http://www.phy.mtu.edu/faculty/Nemiroff.html 25. http://www.phy.mtu.edu/ 26. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 27. http://www.astro.umd.edu/ 28. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 29. https://www.nasa.gov/about/highlights/HP_Privacy.html 30. https://astrophysics.gsfc.nasa.gov/ 31. https://www.nasa.gov/ 32. https://www.nasa.gov/centers/goddard/ 33. http://www.mtu.edu/