Design an accessible comparison using source-labeled lunar renderings

1. Define the frame and evidence

The source packet contains five unchanged NASA Scientific Visualization Studio frames at 00 UT on 1,8,15,22 and 29 January 2026, selected at a fixed seven-day cadence. These are scientific renderings based on lunar terrain/mosaic inputs and an ephemeris, not photographs exposed at those dates. Their provenance is useful evidence precisely because it identifies how the images and numbers were generated.

2. Connect the mechanism

The original source JSON contains hourly geocentric phase, apparent diameter, distance, J2000 coordinates, subsolar/sub-Earth coordinates and position angle. Frame number equals hourly zero-based index plus one. The retained CSV preserves all fields for the five selected records, while the full source JSON and per-image hashes support reproduction. J2000 right ascension is in hours and declination in degrees; neither is local altitude.

Compare the same-width source canvases without separately normalizing each lunar disk. Apparent diameter should vary approximately inversely with distance for a fixed physical radius, but the two fields derive from the same source model and are not independent validation. Published rounding and perspective limit exact equality. Brightness thresholds can misclassify terrain or dark-side detail, so an image-intensity sum is not the documented illuminated area percentage.

An accessible comparison plan records the date, orientation, selection rule, visible terminator and one quantitative prediction before public feedback. A text table supplies the same source geometry for learners who cannot inspect the image. A human reviewer can assess a new frame pair and uncertainty statement, but no supplied visualization certifies actual observing skill, local visibility or instrument calibration.

3. Reconstruct the worked case

The 1 January record has 91.40% illumination, diameter 1985.1 arcsec and distance 361045 km. The 15 January record has 13.49%,1770.9 arcsec and 404728 km. The illumination change is−77.91 percentage points; the smaller angular diameter is consistent with the larger geocentric distance. These are source-model records, not independent sky measurements.

4. Predict and investigate

Predict first: Would resizing every lunar disk to the same diameter preserve an apparent-size comparison?

Download the original JSON, selected CSV and provenance. Verify a timestamp/frame and all fields for one record, then compare two unchanged images and their diameter/distance ratios. Retain a changed-pair prediction and explain why agreement among derived source fields is not independent observational confirmation.

5. Test a changed case

Apply the evidence to a changed case

Compare 22 January with 29 January. What changes in illumination and distance, and what must not be claimed?

Retain the evidence frame, calculations and assumptions before opening public feedback.

Compare a worked response

Illumination rises from 10.31% to 80.22%, a 69.91-percentage-point increase, while distance decreases from 384906 to 366344 km and apparent diameter rises 1862.1→1956.4 arcsec. Do not call these direct photographs, infer local visibility from geocentric coordinates or claim independent ephemeris validation.

6. Retain an observation or image-comparison plan

Preserve the source, units, coordinate epoch/frame, orientation, first prediction and limitations. The screen-based source-image pathway is complete without outdoor viewing. No direct Sun viewing or instrument aiming is requested. Original teaching models are not operational pointing, eclipse or weather predictions; public practice is not independent observing competence.

Primary mechanism or source reference, checked 30 October 2026. Explanations, numerical examples, questions and geometric SVG are original. OpenStax is linked for factual scope, not copied artwork or text. Source NASA media retain their own credits and reuse terms; NASA has not reviewed or endorsed the AI-assisted course.