Subj : Daily APOD Report To : All From : Ben Ritchey Date : Wed Mar 20 2019 03:59:45 APOD: 2019 March 19 - Abell 370: Galaxy Cluster Gravitational Lens 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. 2019 March 19 [2] Abell 370: Galaxy Cluster Gravitational Lens Image Credit: NASA [3] , ESA [4] , Hubble [5] ; Processing & Copyright: Rogelio Bernal Andreo [6] (DeepSkyColors.com [7] ) Explanation: What are those strange arcs? While imaging the cluster of galaxies Abell 370, astronomers noticed an unusual arc. The arc wasn't understood right away -- not until better images showed that the arc was a previously unseen type of astrophysical [8] artifact of a gravitational lens [9] , where the lens was the center of an entire cluster of galaxies [10] . Today, we know that this arc [11] , the brightest arc in the cluster, actually consists of two distorted images [12] of a fairly normal galaxy that happens to lie far in the distance. Abell 370's gravity [13] caused the background galaxies' light -- and others -- to spread out and come to the observer along multiple paths [14] , not unlike a distant light appears through the stem of a wine glass [15] . Almost all of the yellow images featured here [16] are galaxies in the Abell 370 cluster. An astute eye [17] can pick up many strange arcs [18] and distorted arclets [19] , however, that are actually gravitationally lensed [20] images of distant normal galaxies [21] . Studying Abell 370 [22] and its images gives astronomers a unique window into the distribution of normal and dark [23] matter [24] in galaxy clusters [25] and the universe. Tomorrow's picture: welcome to the equinox [26] ------------------------------------------------------------------------------- < [27] | Archive [28] | Submissions [29] | Index [30] | Search [31] | Calendar [32] | RSS [33] | Education [34] | About APOD [35] | Discuss [36] | > [37] ------------------------------------------------------------------------------- Authors & editors: Robert Nemiroff [38] (MTU [39] ) & Jerry Bonnell [40] (UMCP [41] ) NASA Official: Phillip Newman Specific rights apply [42] . NASA Web Privacy Policy and Important Notices [43] A service of: ASD [44] at NASA [45] / GSFC [46] & Michigan Tech. U. [47] ---------- Site notes: [1] archivepix.html [2] image/1903/Abell370Arcs_HubbleAndreo_1840.jpg [3] https://www.nasa.gov/ [4] https://www.esa.int/About_Us/Welcome_to_ESA [5] https://www.nasa.gov/mission_pages/hubble/story/index.html [6] https://en.wikipedia.org/wiki/Rogelio_Bernal_Andreo [7] http://www.deepskycolors.com/ [8] https://science.gsfc.nasa.gov/astrophysics/ [9] http://en.wikipedia.org/wiki/Gravitational_lens [10] ap180326.html [11] ap990104.html [12] http://adsabs.harvard.edu/abs/1999A%26A...347...21B [13] http://spaceplace.nasa.gov/what-is-gravity/en/ [14] http://www.youtube.com/watch?v=BkBNf_nFuhM [15] http://wela.astro.ulg.ac.be/themes/extragal/gravlens/bibdat/engl/DE/didac.html [16] https://www.flickr.com/photos/deepskycolors/47346430111/in/dateposted/ [17] https://thumbs.dreamstime.com/z/cat-myopia-27165838.jpg [18] ap080210.html [19] ap090823.html [20] https://arxiv.org/abs/astro-ph/9312003 [21] ap180305.html [22] http://en.wikipedia.org/wiki/Abell_370 [23] http://en.wikipedia.org/wiki/Dark_matter [24] http://chandra.harvard.edu/xray_astro/dark_matter/ [25] ap070516.html [26] ap190320.html [27] ap190318.html [28] archivepix.html [29] lib/apsubmit2015.html [30] lib/aptree.html [31] https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search [32] calendar/allyears.html [33] /apod.rss [34] lib/edlinks.html [35] lib/about_apod.html [36] http://asterisk.apod.com/discuss_apod.php?date=190319 [37] ap190320.html [38] http://www.phy.mtu.edu/faculty/Nemiroff.html [39] http://www.phy.mtu.edu/ [40] https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html [41] http://www.astro.umd.edu/ [42] lib/about_apod.html#srapply [43] https://www.nasa.gov/about/highlights/HP_Privacy.html [44] https://astrophysics.gsfc.nasa.gov/ [45] https://www.nasa.gov/ [46] https://www.nasa.gov/centers/goddard/ [47] http://www.mtu.edu/ --- Mystic BBS v1.12 A43 (Windows/32) * Origin: FIDONet - The Positronium Repository (1:393/68) .