Astronomy & The Sky
Moon phases, eclipses, sky geometry, stars, spectra, cosmology sketches, and comets
GPS & Relativity
Weak-field + SR clock drift estimates vs altitude and orbital speed.
Nuclear Binding Curve
Qualitative B/A vs A with fusion/fission context.
Seasons & Axial Tilt
Obliquity ~23.4°: declination model vs day of year and noon sun altitude at latitude.
Moon Phases
Sun–Earth–Moon geometry and synodic cycle; lit fraction from phase angle.
Solar Eclipse Geometry
Sun–Moon–Earth: angular sizes, umbra and penumbra cones, orbit tilt.
Lunar Eclipse Geometry
Sun–Earth–Moon: Earth’s shadow on the Moon; total, partial, and penumbral (schematic colors).
Moon: Tidal Locking
Synchronous rotation: same lunar face toward Earth as it orbits.
Mars Retrograde Loop
Earth overtakes Mars: apparent backward loop among the stars (schematic).
Sidereal vs Solar Day
Why noon returns after slightly more than 360° of rotation (~4 min shorter sidereal day).
Axial Precession
Spin axis slowly cones; ~26 kyr cycle changes the pole star (schematic).
Ecliptic & Zodiac Band
Celestial equator vs ecliptic, obliquity, Sun on the yearly path (symbols as map, not astrology).
Hertzsprung–Russell Diagram
Schematic HR regions; drag a star to see main sequence, giants, white dwarfs.
Spectral Lines & Doppler
Absorption lines on a continuum shift with radial velocity (Δλ/λ ≈ v/c).
Cosmic Distance Ladder
Log distance scale with parallax, standard candles, and Hubble-flow cartoon rungs.
Black Hole Shadow (Schematic)
Silhouette and stylized ring; Rₛ scales with mass — not full GR ray tracing.
Sunset Atmospheric Refraction
Geometric vs apparent horizon: lift of the solar disk from a layered atmosphere model.
Comet Orbit, Coma & Tails
Eccentric orbit, coma brightening near the Sun, ion and dust tails, solar wind toggle.