Domain: Natural Science — Astrophysics & Astronomy
Target concept: Total Solar Eclipse

Video generation prompt: The complete process of the apparent positional changes between the Sun and the Moon as observed from Earth during a total solar eclipse.

Evaluation guide:
(i) Target concept: Geometric occlusion of the Sun by the Moon as viewed from Earth during total solar eclipse.
Minimum mechanism: Two coplanar, circular, fronto-parallel disks in fixed perspective; smaller disk (Moon) translating at constant velocity across larger disk (Sun) along a straight chord path; occlusion must be absolute (no transmission), with no parallax or depth cues violating 2D projection.
(ii)Storyline: Frame 1: Sun fully visible, Moon fully outside right edge. → Frame sequence: Moon enters right limb (first contact), progressively covers more of Sun’s disk (increasing dark area), reaches maximum coverage (centered alignment), then uncovers symmetrically. → Frame final: Moon fully exits left limb (fourth contact). Throughout: fixed viewpoint, no rotation, no scale change, no lighting violation; visibility constrained solely by line-of-sight occlusion.

Manual:
Experimental Procedure
1. Position simulated Sun (bright yellow-white circular disk) and Moon (uniformly dark circular silhouette) in same frame, aligned horizontally.
2. Move Moon smoothly and continuously from right to left across Sun’s face, maintaining fixed distance and scale.
3. Ensure Moon fully covers Sun’s center at midpoint, then continues to exit left limb.
Observation of Experimental Phenomena
- Moon’s dark circular silhouette progressively obscures Sun’s bright circular disk.
- Covered region appears uniformly dark; uncovered region retains full brightness and color.
- Ambient scene dims gradually as coverage increases.
Summary of Experimental Principles
- Total solar eclipse results from precise syzygy: Sun, Moon, and Earth aligned, with Moon close enough to appear ≥ same angular size as Sun.
- Apparent motion reflects Moon’s eastward orbital motion relative to Sun’s westward diurnal motion — net effect is Moon moving west-to-east across Sun’s disk.

Prompt Grounding rubric:
level_1: Neither the Sun nor the Moon appears on screen, or only one of the two bodies is shown; or both appear but never move relative to each other; or the Moon drifts in a direction inconsistent with crossing the Sun's face (e.g., moving vertically past a horizontally-aligned Sun); or the two disks are never lined up on the same visual axis at any point.
level_2: The Sun and Moon both appear and are roughly lined up, but the transit is broken by jump cuts, a frozen frame, or a sudden repositioning of either disk; or the two disks only align at the very start and end with no progressive coverage shown in between; or the Moon's disk visibly grows or shrinks in size as it crosses; or the Sun is rendered as a plain solid disk rather than a bright, edge-defined circular source.
level_3: The Sun and Moon are both present and aligned on the same axis; the Moon crosses the Sun's face continuously from one limb to the opposite limb; the covered area grows steadily from first contact to maximum coverage and then shrinks back down again; the Moon's disk stays centered on the Sun's disk at the point of maximum coverage rather than off to one side; the Sun stays roughly centered in the frame throughout.
level_4: Everything for score 3 holds, and in addition: the Moon's leading edge makes first contact on the Sun's western limb and its trailing edge departs from the Sun's eastern limb, consistent with the Moon's eastward orbital motion relative to the Sun; the Sun's outline stays a clean circle; the Moon's silhouette stays one single, unbroken shape with a continuous, non-flickering edge; no extra objects, text, or labels appear in the shot.
level_5: Everything for score 4 holds, and in addition: only the Sun and Moon are ever on screen: no clouds, foreground objects, or camera-frame markers intrude; both disks stay fully inside the frame from the Moon's first appearance to its last; the Sun's disk keeps the same apparent size relative to the Moon's disk across the whole transit, matching a single fixed viewing distance.

Scientific and Causal Correctness rubric:
level_1: The Sun's disk shows an unnatural color (blue, green, or anything but yellow-white); the Moon appears to glow, emit light, or look translucent rather than solid and dark; where the two disks overlap, the region gets brighter instead of darker, as if the light were adding together rather than being blocked; no dark region ever appears where the Moon covers the Sun; a corona or solar prominences show up before totality is reached or are still visible well into the partial phase.
level_2: The Sun is yellow-white but barely stands out from the background sky, as if it weren't actually the brightest thing in the shot; the Moon looks gray, mottled, or cratered like a photograph of the lunar surface rather than a flat black silhouette; the overlap between the two disks never produces a clearly bounded dark patch on the Sun's face; the surrounding sky or scene never gets any darker as coverage increases.
level_3: The Sun is a bright yellow-white disk; the Moon is a uniformly dark, featureless silhouette; as the Moon crosses, the dark patch on the Sun's face grows in a clear, well-defined way; the sky or scene visibly dims as more of the Sun is covered; no part of the covered or uncovered Sun ever shows an inverted or false color.
level_4: Everything for score 3 holds, and in addition: the dark patch on the Sun always matches the Moon's actual projected size and shape at that instant, without appearing larger or smaller than the Moon itself; the still-visible part of the Sun keeps its full brightness and color; the edge of the Moon's silhouette sits flush against the Sun with no glow or halo bleeding out around it; Baily's beads or a diamond-ring flash, if shown at all, only appear right at the instants the Moon's limb is nearly tangent to the Sun's limb, not throughout the crossing.
level_5: Everything for score 3 and score 4 holds, and in addition: at every frame the Moon's edge sits exactly against the Sun's limb with no visible gap or overlap; the Moon's darkness and the uncovered Sun's brightness never waver except as explained by the changing covered area; the dimming of the surrounding scene tracks the covered fraction step for step, growing only as coverage grows; any shift of the sky toward dusk-like tones is confined to the frames of heaviest coverage and fully reverses once the Moon has passed.

Spatiotemporal Consistency rubric:
level_1: The Sun or Moon jumps to a new position between one frame and the next instead of sliding smoothly; either disk suddenly changes size or spins in place; the Sun or Moon briefly isn't in the shot and then reappears without any visible reason; the overall scene brightness swings from bright to dark (or back) with no gradual dimming tied to how much of the Sun is covered; the camera's viewpoint or zoom level changes partway through.
level_2: The crossing motion stutters, with the video visibly freezing or skipping ahead at least twice; the edges of the Sun or Moon flicker, crawl, or shimmer instead of holding a steady outline; any background stars or landscape warps or stretches inconsistently from one frame to the next; the ambient scene dims or brightens in sudden steps that don't line up with how much of the Sun is currently covered.
level_3: The Sun and Moon move smoothly and continuously in the same direction across the whole crossing; any background stays put and geometrically stable; the ambient light in the scene, if shown, dims gradually and in step with the growing coverage rather than in sudden jumps; neither disk clips through the other or changes shape unexpectedly; both disks stay perfectly circular rather than stretching into ovals.
level_4: Everything for score 3 holds, and in addition: the Moon's crossing speed looks constant, without visibly speeding up or slowing down; the Sun's and Moon's circular outlines keep the same round proportions in every frame; if a foreground/background separation is shown, the two layers stay in consistent relative position with no unexplained shift between them.
level_5: Everything for score 3 and score 4 holds, and in addition: the motion of both disks reads as perfectly smooth from first frame to last, with no visible shaking, stray specks, or trailing smear behind either disk; any background sky keeps a consistent, even texture throughout; the clip never stutters, drops a frame, or shows a ghosted double image; neither disk warps or deforms at any point in the sequence.