Astronomy Cafe – Feb 6, 2023

Posted by as Astro Cafe

Video transcript of meeting

  • Silent Sky at Langham Court Theatre – performances Jan 25 to Feb 11
    • Positive comments from RASC members who attended performances, especially Sara Ellison’s presentation at the end of the Sunday afternoon performance.
    • Full bus from Berwick House attended the Sunday afternoon performance
    • Lots of seats are available for Wed, Thu & Fri upcoming performances
    • History of the production by Jim Hesser
  • Welcome from Jeff Pivnick
  • Beginners’ SIG – tomorrow evening – David Lee
  • Special General Meeting – Feb 13, 2023 – Randy Enkin
    • Need to adopt new bylaws for Victoria Centre
    • Presentation: A Brief History of Galaxies… – Sara Ellison
  • Black Holes
    • How can a black hole conserve angular momentum? – Randy Enkin
      • Conservation of angular momentum examples
        • Solar system
        • Earth-Moon system
      • Black Holes – 1915 Albert Einstein, 1916 Karl Schwarzchild (point singularity), 1963 Roy Kerr (ringularity)
    • What really happens at the black hole singularity? – John McDonald
      • Black Holes can be explained somewhat by Gravity (very large things) and Quantum Theory (very small things)
      • What happens to information that falls into a Black hole? We don’t know.
      • Black Holes are not likely a singularity, so it’s unknown what form they actually take
      • Entropy – measure of the disorder of things
  • Uranus – Jeff Pivnick
    • Relative distances of planets in solar system
    • Distance from the Sun to Saturn is about the same as the distance from Saturn to Uranus
    • Photos of Uranus taken by John McDonald and Lucky Budd – Zenfolio | RASC Victoria Centre | Search
    • William Herschel, an astronomer, reflecting telescope maker, musician and composer
      • Discovered Uranus on March 13, 1781
      • Discovered infrared light
      • Caroline Herschel – first professional astronomer (paid by the king)
      • NGC list was first compiled by the Herschels
  • Horizons – Dorothy Paul
    • Observed from the White Mountains of California in October 2022
    • Camped for 10 days with 7 days of good observing skies
    • SQM at least 21.8, with good transparency and stability
    • Dorothy and Miles observed the southern sky from 38.5º north, observing the Grus constellation at -50º altitude!
    • Observed stars right down to the True Horizon at -51.5º
    • Discussion of the term Astronomical Horizon
  • Comet C/2022 E3 (ZTF) photos – Dave Payne
    • Globular Cluster discovered by Caroline Herschel
    • Comet C/2022 E3 (ZTF) on Jan 28th
    • Diatomic carbon causes the green colour in many comets, including this one
  • RASC Victoria AGM tentatively to be held on March 13, predicated on the new bylaws being passed.
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