Earth Science, Astronomy, Space / Principles and Exploration
Moon phases — principles and investigation
The Moon has a hemisphere that receives sunlight, but the proportion of the bright portion seen from Earth varies depending on its orbital position. Change the angle of the moon measured from the direction of the sun and compare the rising, rising, falling, and falling angles. Changes in the moon's phases must be distinguished from the phenomenon caused by the Earth's shadow blocking the moon.
How does it work?
90° is upstream, 50%, and 180° is net, 100%. The right side of the waxing moon and the left side of the waning moon are bright.
f = (1−cos θ)/2
Try this investigation
- Drag the moon for the layout seen from above or use the angle slider/45° button. The disk below is seen from the ground in the Northern Hemisphere.
- Execute and record one rotation of the phase current and network respectively. After one turn, check the ratio of the bright part of the first angle.
- Additional records are made of Hahyun and Sak, and the names of all eight shapes in the analysis stage are guessed correctly.
Interpreting your results
What is the direct reason why the phases of the moon change?
The moon is always bright in the hemisphere facing the sun. The direction from which the hemisphere is viewed from the Earth changes, creating a phase.
Assumptions and limitations
Assume a circular orbit, parallel solar power, and a positive disk in the northern hemisphere. Sizes and distances are to illustrative scale and phase names are divided into eight divisions spaced at 45° intervals. Disk rotation, tilt, and eclipse phenomena at the observation site are omitted. Phases are not created by the Earth's shadow.