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. 2020 January 8 [2]See Explanation. Clicking on the picture will download the highest resolution version available. Galaxies in the River Image Credit & [3]Copyright: [4]Star Shadows Remote Observatory, [5]PROMPT, CTIO Explanation: Large galaxies grow by eating small ones. [6]Even our own galaxy engages in a sort of galactic [7]cannibalism, absorbing small galaxies that are too close and are [8]captured by the Milky Way's gravity. In fact, the [9]practice is common in the universe and illustrated by this striking pair of interacting galaxies from the banks of the southern constellation [10]Eridanus, [11]The River. Located over 50 million light years away, the large, distorted [12]spiral NGC 1532 is seen locked in a gravitational struggle with dwarf galaxy NGC 1531 (right of center), a struggle the smaller galaxy [13]will eventually lose. Seen edge-on, spiral NGC 1532 spans about 100,000 light-years. Nicely detailed in this sharp image, the NGC 1532/1531 pair is thought to be similar to the well-studied system of face-on spiral and small companion [14]known as M51. Tomorrow's picture: happy perihelion __________________________________________________________________ [15]< | [16]Archive | [17]Submissions | [18]Index | [19]Search | [20]Calendar | [21]RSS | [22]Education | [23]About APOD | [24]Discuss | [25]> __________________________________________________________________ Authors & editors: [26]Robert Nemiroff ([27]MTU) & [28]Jerry Bonnell ([29]UMCP) NASA Official: Phillip Newman [30]Specific rights apply. [31]NASA Web Privacy Policy and Important Notices A service of: [32]ASD at [33]NASA / [34]GSFC & [35]Michigan Tech. U. References 1. https://apod.nasa.gov/apod/archivepix.html 2. https://apod.nasa.gov/apod/image/2001/NGC1532-final3_4096r.jpg 3. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 4. http://www.starshadows.com/index.cfm 5. http://user.physics.unc.edu/~reichart/promptteam.html 6. https://apod.nasa.gov/apod/ap050529.html 7. http://www.cosmotography.com/images/galaxy_cannibalism.html 8. http://arxiv.org/abs/astro-ph/0407566 9. https://www.nasa.gov/image-feature/goddard/2017/hubble-catches-a-galaxy-duo-by-the-hare 10. http://www.hawastsoc.org/deepsky/eri/index.html 11. https://apod.nasa.gov/apod/ap160102.html 12. http://ourcolorfulcosmos.com/mazlin/galaxies/ngc-1531-2-widefield/ 13. https://apod.nasa.gov/apod/ap080619.html 14. https://apod.nasa.gov/apod/ap150502.html 15. https://apod.nasa.gov/apod/ap200107.html 16. https://apod.nasa.gov/apod/archivepix.html 17. https://apod.nasa.gov/apod/lib/apsubmit2015.html 18. https://apod.nasa.gov/apod/lib/aptree.html 19. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search 20. https://apod.nasa.gov/apod/calendar/allyears.html 21. https://apod.nasa.gov/apod.rss 22. https://apod.nasa.gov/apod/lib/edlinks.html 23. https://apod.nasa.gov/apod/lib/about_apod.html 24. http://asterisk.apod.com/discuss_apod.php?date=200108 25. https://apod.nasa.gov/apod/ap200109.html 26. http://www.phy.mtu.edu/faculty/Nemiroff.html 27. http://www.phy.mtu.edu/ 28. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html 29. http://www.astro.umd.edu/ 30. https://apod.nasa.gov/apod/lib/about_apod.html#srapply 31. https://www.nasa.gov/about/highlights/HP_Privacy.html 32. https://astrophysics.gsfc.nasa.gov/ 33. https://www.nasa.gov/ 34. https://www.nasa.gov/centers/goddard/ 35. http://www.mtu.edu/