# Read Moon-phase diagrams in ManYue: separate the lit hemisphere from the visible bright disk
Language: en
Canonical: [Read Moon-phase diagrams in ManYue: separate the lit hemisphere from the visible bright disk]()
中文：[中文 HTML]()
English: [English HTML]()
Published: 2026-11-13T00:00:00+08:00
Modified: 2026-11-13T09:43:51+08:00
Author: Bison
Trace sunlight, the Earth observer and lunar position through new, full and quarter phases without confusing ordinary phases with Earth-shadow eclipses.
English translation of the [Chinese original](), translated on 2026-11-13. Original publication dates, attribution, code and version notes are retained.
Black-and-white circles in a Moon diagram may show a lit hemisphere in space or the disk seen from Earth. Read an original diagram in ManYue and separate these viewpoints. This is diagram reasoning, without lasers, bright lamps or telescopes, and it predicts no real phase from a fictional date. The app provides reading and return access, not automatic astronomical measurement.
## Separate the position diagram from the observer disk
Use an original or authorised page, labelling the space-position diagram A and Earth-view disks B. Put Earth centrally, Sun left and four lunar positions in A, with corresponding appearances in B. Keep viewpoints distinct and record title, location, legend and scale assumptions. A convenient planar diagram does not preserve actual sizes or distances or imply an eclipse at every apparent alignment.
## Determine the lit hemisphere from sunlight first
In A, simplify sunlight as parallel arrows from left to right and mark the Sun-facing half of each lunar sphere. Re-evaluate illumination at every location rather than shade the page top or Earth-facing half automatically. State that eclipses and complex scattering are outside this ideal diagram. Light-propagation arrows differ from orbital arrows; distinct line styles prevent interpreting both as one motion.
## View the new-Moon position from Earth
Place the Moon schematically between Earth and Sun, mark its Sun-facing hemisphere and then draw the Earth-to-Moon sightline. Earth mainly faces the side not directly sunlit, giving the new-Moon disk in B, not an entirely unilluminated sphere. Orbital inclination means an ordinary new Moon is not automatically a solar eclipse. This simplified line is not an instruction to look at the Sun.
## Check visible illumination for full and quarter phases
Across Earth from the Sun, the visible side is mainly lit, producing a full-Moon disk. At positions roughly perpendicular to the Earth–Sun direction, about half the visible disk is bright: the quarter phases, not half a physical Moon. Without orbital order and viewing orientation, do not assign first versus last quarter or a universal left/right bright edge to the two static positions. Establish the legend’s conditions before naming them.
For each position write two separate judgments: which hemisphere faces sunlight, and how much of the Earth-visible disk is bright. A roughly half-lit sphere can show an almost fully bright disk or a dark disk from Earth. This lets you reconstruct the view from the observer even after the page’s small shaded circles are rotated.
## Record ordinary phases separately from eclipses
NASA explains ordinary phases through illumination and viewing geometry, not Earth’s shadow cutting away a different piece daily. An eclipse diagram needs its own shadow and entry conditions. Do not label all darkness as terrestrial shadow or claim every full Moon creates an eclipse. In a comic, read title, wording and geometry before identifying an eclipse; black fill alone may simply show a side not directly sunlit.
## Retain the work’s own premises when returning
In ManYue, zoom A to inspect Sun and observer, then B for appearances. Note supplied north, orbital sequence or dates. A clearly fictional system may use different premises and is not automatically wrong under Earth–Moon rules. For a claimed real diagram with missing orientation, record that omission instead of using screen up as celestial north. This checks stated consistency without inferring an exact time or location from a crescent.
## Check mixed viewpoints and left-right reversal
For mismatched A and B shading, first check viewpoint confusion, then mirroring or missed legend conditions. Rotating the device changes page orientation, not actual lunar illumination, so keep display conditions fixed. Retain the source and a separate checking sketch instead of redrawing its arrows and claiming they were original. Unknown orientation remains unknown; no app phase recognition or physical astronomical observation is claimed.
## Leave and return to distinguish two kinds of darkness
Leave and return to the whole page, tracing light before sightlines and reconstructing new, full and two half-lit disks. Keep both diagrams, viewing assumptions, separate eclipse example, source location and unknowns. Explain lit hemisphere versus visible brightness and ordinary darkness versus Earth shadow. Success is geometry, not memorised screen-side patterns. New legends or fictional worlds need new premises and traceable source locations.
## Related guides and sources
[ManYue maps inside comics: read the legend before checking a route](); [ManYue: Read mirror reflections without confusing page and scene directions]().
Checked on November 13, 2026: [Apple public information]() lists ManYue 2.0.5, requiring iOS / iPadOS 15.0 or later. See the [official App Store]() for published capabilities; verify specific controls in the installed version.
Method reference: [NASA: Moon phases and illumination](). Samples, passages and controls are original exercises. Sources establish definitions and checking methods rather than new automatic analysis in the app. Manual records may be kept externally, and unknown fields should remain explicit. This article does not claim step-by-step testing on a physical device, private server or every output environment.