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. 2026 May 20 [2]A dark and whispy cloud blocks the background light from surrounding gas and stars. It resembles the head, snout, and jaws of a wolf. The Dark Wolf Nebula Image Credit & Copyright: [3]William Vrbasso Text: [4]Keighley Rockcliffe ([5]NASA [6]GSFC, [7]UMBC CSST, [8]CRESST II) Explanation: A dark wolf lies in gum. No, this isn’t a riddle! [9]Today's image features [10]the Dark Wolf Nebula ([11]Sandqvist–Lindroos 17), a spooky dust cloud embedded within the [12]Gum 55 ([13]RCW 113) Nebula in [14]the Scorpius constellation. While [15]dust is a pest to us, it serves a vital role in creating the necessary conditions for [16]stars to be born. The Dark Wolf absorbs the intense [17]ultraviolet and [18]visible light emitted by young stars in Gum 55 and re-emits it at longer, mainly [19]infrared, wavelengths. This prevents the higher energy light from heating up the gas in the region. When a region of gas is cool enough, gravity takes over and causes the gas to collapse into a star. Not only does [20]dust act as an interstellar thermostat, but it is also [21]the meet-cute for single hydrogen atoms forming molecular hydrogen, the building block for stars. The seemingly sinister Dark Wolf is actually a harbinger of cosmic life. Tomorrow's picture: write __________________________________________________________________ [22]< | [23]Archive | [24]Submissions | [25]Index | [26]Search | [27]Calendar | [28]RSS | [29]Education | [30]About APOD | [31]Discuss | [32]> __________________________________________________________________ Authors & editors: [33]Robert Nemiroff ([34]MTU) & [35]Jerry Bonnell ([36]UMCP) NASA Official: Amber Straughn [37]Specific rights apply. [38]NASA Web Privacy, [39]Accessibility, [40]Notices; A service of: [41]ASD at [42]NASA / [43]GSFC, [44]NASA Science Activation & [45]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2605/dark_wolf.jpg 3. https://www.stellaraustralis.com/ 4. https://kerockcliffe.com/ 5. https://science.gsfc.nasa.gov/sci/bio/keighley.e.rockcliffe 6. https://www.nasa.gov/goddard/ 7. https://csst.umbc.edu/directory/ 8. https://cresst2.umd.edu/ 9. https://www.instagram.com/p/DKYkOj9PUVg/ 10. https://www.eso.org/public/news/eso2416/ 11. https://ui.adsabs.harvard.edu/scan/manifest/1976A&A....53..179S 12. https://articles.adsabs.harvard.edu/pdf/1955MmRAS..67..155G 13. https://articles.adsabs.harvard.edu/pdf/1960MNRAS.121..103R 14. https://apod.nasa.gov/apod/ap210616.html 15. https://science.nasa.gov/universe/dust-in-the-stellar-wind-a-cosmological-primer/ 16. https://science.nasa.gov/universe/stars/ 17. https://science.nasa.gov/ems/10_ultravioletwaves/ 18. https://science.nasa.gov/ems/09_visiblelight/ 19. https://science.nasa.gov/ems/07_infraredwaves/ 20. https://astronomy.swin.edu.au/cosmos/d/Dust+Grain 21. https://en.wikipedia.org/wiki/Meet_cute 22. https://apod.nasa.gov/apod/ap260519.html 23. https://apod.nasa.gov/apod/archivepix.html 24. https://apod.nasa.gov/apod/lib/apsubmit2015.html 25. https://apod.nasa.gov/apod/lib/aptree.html 26. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 27. https://apod.nasa.gov/apod/calendar/allyears.html 28. https://apod.com/feed.rss 29. https://apod.nasa.gov/apod/lib/edlinks.html 30. https://apod.nasa.gov/apod/lib/about_apod.html 31. https://asterisk.apod.com/discuss_apod.php?date=260520 32. https://apod.nasa.gov/apod/ap260521.html 33. http://www.phy.mtu.edu/faculty/Nemiroff.html 34. http://www.phy.mtu.edu/ 35. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 36. http://www.astro.umd.edu/ 37. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 38. https://www.nasa.gov/about/highlights/HP_Privacy.html 39. https://www.nasa.gov/general/accessibility/ 40. https://www.nasa.gov/privacy/ 41. https://astrophysics.gsfc.nasa.gov/ 42. https://www.nasa.gov/ 43. https://www.nasa.gov/centers/goddard/ 44. https://science.nasa.gov/learners 45. http://www.mtu.edu/