View from Above (North Pole)
Sunlight ->
from the Sun
Earth
Earth's Shadow
(only matters for eclipses)
Your view
Moon motion
Drag the Moon around Earth's orbit
As Seen from Earth
Sun is this way
E
W
Waxing = lit fraction increasing; Waning = decreasing.
Waxing
Schematic (not to scale).
Speed
1x
5x
10x
Focus Moon
Moon controls focused
WAXING →
Day 0 of 29.5
New
Crescent
1st Qtr
Gibbous
Full
Gibbous
3rd Qtr
Crescent
Rises ~6 PM · Sets ~6 AM
Phase
Full Moon
Angle
0
deg
Illuminated
100
%
Days since new
14.8
d
Illumination model
f = (1 + cos α)/2 =
1.000
What to notice
Model notes
Observable:
the lit fraction grows or shrinks as the Moon moves.
Model:
illumination depends on the Sun-Earth-Moon phase angle $\alpha$.
Inference:
phases are geometry, not Earth's shadow.
Schematic geometry (not to scale, no orbital tilt).
Illumination uses $f = \frac{1 + \cos\alpha}{2}$ with $\alpha$ in degrees.
Earth's shadow appears only when toggled and only for eclipse insight.