MSGID: 1:153/757@fidonet 61476677   
   PID: MBSE-FIDO 1.0.7.22 (GNU/Linux-x86_64)   
   CHRS: CP437 2   
   TZUTC: -0800   
   TID: MBSE-FIDO 1.0.7.22 (GNU/Linux-x86_64)   
                           Astronomy Picture of the Day   
      
       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.   
      
                                  2021 December 7   
      
                Ninety Gravitational Wave Spectrograms and Counting   
        Image Credit: NSF, LIGO, VIRGO, KAGRA, Georgia Tech, Vanderbilt U.;   
                      Graphic : Sudarshan Ghonge & Karan Jani   
      
      Explanation: Every time two massive black holes collide, a loud   
      chirping sound is broadcast out into the universe in gravitational   
      waves. Humanity has only had the technology to hear these unusual   
      chirps for the past seven years, but since then we have heard about 90   
      -- during the first three observing runs. Featured above are the   
      spectrograms -- plots of gravitational-wave frequency versus time -- of   
      these 90 as detected by the giant detectors of LIGO (in the USA), VIRGO   
      (in Europe), and KAGRA (in Japan). The more energy received on Earth   
      from a collision, the brighter it appears on the graphic. Among many   
      science firsts, these gravitational-radiation chirps are giving   
      humanity an unprecedented inventory of black holes and neutron stars,   
      and a new way to measure the expansion rate of our universe. A fourth   
      gravitational wave observing run with increased sensitivity is   
      currently planned to begin in 2022 December.   
      
                          Tomorrow's picture: comet tails   
        __________________________________________________________________   
      
          Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)   
               NASA Official: Phillip Newman Specific rights apply.   
                   NASA Web Privacy Policy and Important Notices   
                         A service of: ASD at NASA / GSFC   
                                & Michigan Tech. U.   
   --- MBSE BBS v1.0.7.22 (GNU/Linux-x86_64)   
    * Origin: The Rusty MailBox - Penticton, BC Canada (1:153/757)   
   SEEN-BY: 1/123 14/0 90/1 103/705 105/81 120/340 123/131 129/305 134/100   
   SEEN-BY: 153/0 105 135 757 6809 218/700 840 221/1 6 226/30 227/114   
   SEEN-BY: 229/424 426 428 664 700 240/1120 5832 249/206 317 400 261/38   
   SEEN-BY: 282/1038 301/1 113 812 317/3 322/757 335/364 341/66 342/200   
   SEEN-BY: 460/58 633/280 712/848 920/1 4500/1 5020/1042 5058/104   
   PATH: 153/757 221/6 301/1 229/426