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.
- Starting with our solar system:
- Planets:
- Mercury, smaller than earth’s moon, no atmosphere to speak of, no moons, tidally locked with the sun
- Venus, no moons, hottest planet in solar system due to thick carbon dioxide atomsphere
- Earth, one planet-sized moon, only known location of life
- Mars, thin carbon dioxide atmosphere, two small, irregularly-shaped moons
- (Many asteroids in main asteroid belt, between orbits of Mars and Jupiter)
- 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)
- 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)
- Uranus, planet with axis of rotation closest to the ecliptic, 27 known moons
- Neptune, one large moon, Triton, among 14 known moons
- Dwarf Planets:
- Ceres, only dwarf planet in the asteroid belt
- Pluto/Charon double dwarf planet system
- Haumea
- Makemake
- Eris, largest dwarf planet
- Sedna
- Planets:
- Other known solar systems:
- 1,795 exoplanets
- 461 exoplanets in multiplanet systems
- Total of 1,114 exoplanet systems, all within our galaxy
- Nearest known star, other than the sun: Proxima Centauri, 4.2 light-years distant
- Number of stars in the Milky Way, our galaxy: ~300 billion
- Number of galaxies in the known universe: ~100-200 billion