Daniel ast103_02: Discovering the Universe for Yourself: Supplement

  1. Stars in constellations are NOT usually in a common gravitationally-bound system of stars other than that they are all part of the Milky Way and in the near part of the Milky Way.
    1. Sky map, Las Vegas, 2024/01/23 05:00:00 = Jan22: 9 pm / Weather. Sky map, white background.

  2. The local link / general link: sky_map_all_sky.html).

  3. great circle
  4. The celestial equator, ecliptic, and the Milky Way are all great circles that cut the celestial sphere in half, but they do NOT have a common axis.
  5. The Babylonian astronomers divided the circle into 360° as explicated in the figure below (local link / general link: babylonian_360_degrees.html).

  6. See celestial sphere | 1:45: Best celestial sphere video ever!!! below (local link / general link: celestial_sphere_videos.html). It makes the celestial sphere idea very clear.

  7. Apparent in astronomy means as seen from Earth.
  8. The figure below (local link / general link: declination_altitude_2.html) proves these formulae.

  9. The kinematics of the Earth's axial precession is explicated by the figure below (local link / general link: axial_precession_animation.html).

  10. As well as the axial precession (which is a change direction without necessarily a change in Earth's axial tilt size), the Earth's axial tilt size does vary in time too as shown in the figure below (local link / general link: axial_tilt.html).

  11. No! The Big Bang theory was NOT posited to explain the expansion of the universe. It's sort of the other way around: in order to have a Big Bang, you must have the expansion of the universe and other things. The Big Bang theory was adopted as a way to explain the cosmic composition, cosmic microwave background (CMB) T = 2.7260(13) K, and other things too.
  12. Large Magellanic Cloud (LMC) distance = 163,000 light-years (49.97 kpc) and Small Magellanic Cloud (SMC) distance = 203.7 ± 1.5 kly (62.44 ± 0.47 c. So the answer is right only to 1 digit accuracy.