Subj : Daily APOD Report To : All From : Ben Ritchey Date : Mon Dec 31 2018 09:25:56 Astronomy Picture of the Day Astronomy Picture of the Day Discover the cosmos! [1] Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2018 December 31 [2] The Witch Head Nebula Image Credit & Copyright: Digitized Sky Survey [3] (POSS II); Processing: Utkarsh Mishra [4] Explanation: Double, double toil and trouble; [5] Fire burn, and cauldron bubble .... maybe Macbeth should have consulted the Witch Head Nebula. A frighteningly shaped reflection nebula [6] , this cosmic crone is about 800 light-years away though. Its malevolent visage seems to glare toward nearby bright star Rigel in Orion [7] , just off the right edge of this frame. More formally known as IC 2118, the interstellar cloud [8] of dust and gas is nearly 70 light-years across, its dust grains reflecting Rigel's starlight. In this composite portrait [9] , the nebula's color is caused not only by the star's intense bluish light but because the dust grains scatter blue light [10] more efficiently than red. The same physical process causes Earth's daytime sky to appear blue [11] , although the scatterers in planet Earth's atmosphere are molecules of nitrogen and oxygen. Free Download: 2019 APOD Calendar (v5) [12] Tomorrow's picture: galaxy hat ------------------------------------------------------------------------------- < [13] | Archive [14] | Submissions [15] | Index [16] | Search [17] | Calendar [18] | RSS [19] | Education [20] | About APOD [21] | Discuss [22] | > [23] ------------------------------------------------------------------------------- Authors & editors: Robert Nemiroff [24] (MTU [25] ) & Jerry Bonnell [26] (UMCP [27] ) NASA Official: Phillip Newman Specific rights apply [28] . NASA Web Privacy Policy and Important Notices [29] A service of: ASD [30] at NASA [31] / GSFC [32] & Michigan Tech. U. [33] ---------- Site notes: [1] archivepix.html [2] image/1812/WitchHeadNebula_Mishra_2725.jpg [3] http://archive.stsci.edu/dss/copyright.html [4] https://www.flickr.com/photos/163350986@N06/ [5] http://www.potw.org/archive/potw283.html [6] ap011228.html [7] ap150316.html [8] http://arxiv.org/abs/1007.0241 [9] https://www.flickr.com/photos/163350986@N06/45335453644/in/dateposted-public [10] http://leo.astronomy.cz/mix/mix.html [11] http://math.ucr.edu/home/baez/physics/General/ BlueSky/blue_sky.html [12] https://apod.nasa.gov/apod/image/1812/ApodCalendar2019v5_Dave.pdf [13] ap181230.html [14] archivepix.html [15] lib/apsubmit2015.html [16] lib/aptree.html [17] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search [18] calendar/allyears.html [19] /apod.rss [20] lib/edlinks.html [21] lib/about_apod.html [22] http://asterisk.apod.com/discuss_apod.php?date=181231 [23] ap190101.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] 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/ --- Mystic BBS v1.12 A42 (Windows/32) * Origin: FIDONet - The Positronium Repository (1:393/68) .