Astronomy Update

Astronomy Update

The brightest star in the picture above is Mintaka, from Orion’s Belt. We just adopted a cat, and named her Mintaka. I think that calls for an astronomy update — just the basics, stuff that everyone should know much of.

  1. Starting with our solar system:
    1. Planets:
      1. Mercury, smaller than earth’s moon, no atmosphere to speak of, no moons, tidally locked with the sun
      2. Venus, no moons, hottest planet in solar system due to thick carbon dioxide atomsphere
      3. Earth, one planet-sized moon, only known location of life
      4. Mars, thin carbon dioxide atmosphere, two small, irregularly-shaped moons
      5. (Many asteroids in main asteroid belt, between orbits of Mars and Jupiter)
      6. Jupiter, largest of four gas giants and everything else in the solar system except the sun, 67 known moons (four are planet-sized, and three of those four have known or suspected sub-surface water oceans — Europa, Callisto, and Ganymede)
      7. Saturn, gas giant with most extensive ring system in the solar system, 150 known moons and moonlets, including one planet-sized moon, Titan, with a thick atmosphere and possible subsurface ocean, and another moon with a known subsurface water ocean, Enceladus)
      8. Uranus, planet with axis of rotation closest to the ecliptic, 27 known moons
      9. Neptune, one large moon, Triton, among 14 known moons
    2. Dwarf Planets:
      1. Ceres, only dwarf planet in the asteroid belt
      2. Pluto/Charon double dwarf planet system
      3. Haumea
      4. Makemake
      5. Eris, largest dwarf planet
      6. Sedna
  2. Other known solar systems:
    1. 1,795 exoplanets
    2. 461 exoplanets in multiplanet systems
    3. Total of 1,114 exoplanet systems, all within our galaxy
  3. Nearest known star, other than the sun: Proxima Centauri, 4.2 light-years distant
  4. Number of stars in the Milky Way, our galaxy:  ~300 billion
  5. Number of galaxies in the known universe:  ~100-200 billion

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