Domain: Natural Science — Astrophysics & Astronomy
Target concept: Fast bright streaks cross the night sky, appearing and disappearing rapidly, with only brief residual trails.

Video generation prompt: Visual phenomenon of a meteor entering Earth's atmosphere

Evaluation guide:
(i) Target concept: Atmospheric entry of extraterrestrial matter resulting in transient luminous phenomenon.
Minimum mechanism: Object must possess sufficient kinetic energy to heat atmospheric gases to incandescence upon collision; entry must occur at oblique angle through upper atmosphere; no combustion or propulsion required.
(ii)Storyline: [Phase 1] Night sky established: static, dark, with visible stars. [Phase 2] Instantaneous appearance of bright streak at upper boundary, initiating rapid downward motion. [Phase 3] Streak traverses field-of-view in continuous, unbroken motion, maintaining descending trajectory. [Phase 4] Streak vanishes abruptly at lower boundary or within frame; no exit trail beyond termination point. [Phase 5] Brief residual trail appears *exclusively* along prior path, fades monotonically, and disappears fully before video concludes. Perspective: Fixed, ground-based, wide-field; no camera motion; stars remain stationary throughout.

Manual:
Experimental Procedure
1. Set up fixed wide-angle view of clear night sky.
2. Introduce a small, high-velocity luminous object entering atmosphere from upper edge.
3. Record 10-second sequence capturing full transit and immediate aftermath.
Observation of Experimental Phenomena
A fast, bright white-yellow streak descends linearly or shallowly across the night sky, appearing instantaneously, moving rapidly, and vanishing within seconds; a faint, short-lived residual trail lingers exactly along its path and fades completely before video ends.
Summary of Experimental Principles
Meteoroids enter Earth’s atmosphere at hypersonic speeds; frictional heating causes ablation and ionization, producing brief incandescence; the luminous streak is the visible plasma trail; rapid cooling and dispersion cause quick extinction, leaving only a transient afterglow.

Prompt Grounding rubric:
level_1: No meteor-like streak appears anywhere in the video; the sky is not a dark starfield (e.g., it is daytime, cloudy, or an indoor/studio backdrop); no bright transient object is shown at all.
level_2: A bright streak appears against a night sky, but it is stationary, moves too slowly to read as a meteor, or travels upward/sideways instead of descending; the streak stays visible for the whole clip without vanishing, or the fading trail is missing entirely, or the trail never fades and stays as a permanent line.
level_3: A single bright streak crosses the dark, star-filled sky quickly along a straight or gently curved downward path, then disappears either within the frame or by exiting at the frame's lower boundary, consistent with a descending atmospheric-entry trajectory; a short glowing trail appears right after the streak passes and fades away completely before the clip ends.
level_4: Everything required for a 3 holds, and in addition: the streak enters near the top of the frame and extinguishes lower in the frame, matching a descending atmospheric-entry path; the trail sits only along the streak's own track and is fully gone well before the ten-second mark; no other bright object (a second streak, a plane light, a firework) competes with the meteor for attention.
level_5: Everything required for a 4 holds, and in addition: the streak is already at full brightness the instant it enters the frame rather than fading in gradually; the fading trail hugs only the streak's own path with no separate glow or halo spreading away from that line; at least three stars are visible in the background and stay fixed in place across the clip, confirming a steady, ground-based camera view of a real night sky.

Scientific and Causal Correctness rubric:
level_1: The event contradicts basic meteor physics: the streak climbs or moves sideways away from the ground instead of descending, it visibly balloons outward like a fireball or explosion, it trails smoke or drops visible burning debris, or its trail keeps glowing at constant brightness instead of fading. Any of these breaks the basic atmospheric-entry phenomenon, regardless of the streak's color.
level_2: The streak's motion instead resembles a satellite or aircraft light: near-constant speed with no sense of a body burning through resistance, a perfect circular arc rather than a straight or gently curving path, or a trail that lingers far longer than a couple of seconds or spreads out sideways instead of staying thin along the path.
level_3: The streak is brightest at its leading tip and dims toward the tail; its color may be white, yellow-white, or, for an unusually bright bolide, tinted green or blue, all of which are physically plausible meteor colors; its path is a straight line or a shallow descending curve; the trail is dimmer than the streak itself and fades away smoothly, with no sparks, fragmenting pieces, or secondary flashes breaking off the main streak.
level_4: Everything required for a 3 holds, and in addition: brightness clearly falls off from the leading tip to the trailing end rather than staying even along the streak's length; the fading trail matches the streak's own orientation and length rather than being noticeably longer or shorter; the streak does not swing through an implausible color change (e.g., red suddenly turning blue) inconsistent with typical meteor emission.
level_5: Everything required for a 4 holds, and in addition: no glowing afterimage lingers once the trail has naturally faded out; there is no stray flare, reflection, or artifact that could be mistaken for a second trail; the timing lines up so the trail only appears once the streak has passed a given point and keeps fading only after the streak itself has fully disappeared, with the streak's peak brightness and the trail's peak brightness never overlapping in time.

Spatiotemporal Consistency rubric:
level_1: Severe spatiotemporal breaks: the streak suddenly jumps to a different position or angle between frames; the night sky background abruptly changes (e.g., cuts to solid black and back, or swaps to a different starfield); the sky's overall brightness jumps up or down with no visible source or transition; or the streak itself breaks apart and reforms (gaps appear in its body, or it splits into disconnected pieces).
level_2: Moderate inconsistencies: the streak's width changes abruptly partway through its motion; the trail appears before the streak has finished crossing the frame; background stars visibly shift position or blink on and off; or the streak's speed noticeably surges and stalls in ways that don't match a body moving in a straight line across the sky.
level_3: The streak advances smoothly across the frame with continuous positional progression; the trail appears in the correct spot relative to where the streak has already passed; the starfield background stays put (no panning, zooming, or rotating); the sky's overall brightness and any horizon glow stay the same from the first frame to the last; there is no visible stutter or dropped-frame look to the motion.
level_4: Everything required for a 3 holds, and in addition: the streak's width looks steady rather than pulsing or tapering unnaturally; the trail tracks directly behind the streak's own path without drifting sideways from it; a horizon line, if visible, stays level and in the same place; the stars in the background don't flicker or change position from one moment to the next.
level_5: Everything required for a 4 holds, and in addition: the streak's motion looks continuously fluid with no stop-start stepping or strobing to it; the trail's brightness fades away smoothly and gradually rather than in visible jumps or sudden cuts; the spatial relationships between the streak, its trail, the stars, and the horizon all stay geometrically coherent throughout the clip, with nothing sliding out of alignment.