AZ MODESTSOFT SCIENCE · LOCAL PREVIEW
Why does the Moon change shape?
Move the Moon around Earth. Watch what an observer on Earth sees.
Choose a Moon shape or drag the Moon around Earth.
Look! The right half of the Moon looks bright.
The Moon is round the whole time. We just see different amounts of its sunlit half.Watch the sunlight, not Earth's shadow
The Moon always has a sunlit hemisphere. As the Moon moves around Earth, we see different amounts of that illuminated half. The changing view causes its phases, not the shadow of Earth. Eclipses are a separate phenomenon.
This educational simulation uses a circular inclined orbit and mean periods: about 27.32 days to orbit relative to stars and 29.53 days for the phase cycle. It does not predict actual calendar phase dates, eclipses, or the Moon's appearance from a specific observing site.
Globe sizes, Earth–Moon separation, and perspective are exaggerated for readability. The prototype uses locally hosted 2K NASA-derived Earth and Moon color maps; if an image fails, procedural fallback colors are not real geographical or lunar images. Relief and clouds are not physically simulated.
Primary astronomy reference: NASA Moon Phases. Texture credits: NASA Earth Observatory Blue Marble: Next Generation (July), Reto Stöckli/NASA GSFC; NASA Scientific Visualization Studio CGI Moon Kit, Ernie Wright/LRO-LROC/LOLA teams. Resized local JPEG derivatives are described in the asset provenance record. This preview has no analytics or advertising.