Jupiter
Jupiter on December 1, 2012 · two days before opposition — with the Red Spot dead center
This is Jupiter as a weather planet, not as a smooth ball. The bright Equatorial Zone runs across the middle. Below it a narrow, sharply bounded dark belt adjoins it, and farther down follows a second, paler one. Above the zone lies a broad and visibly disturbed belt, and at its inner edge — almost exactly at the center of the frame — sits a reddish oval where the dark belt ends as if cut off and breaks into oblique streaks to its right. Toward both edges color and contrast weaken: those are the polar regions.
The belts tell you which way is up. The narrow, highest-contrast belt lies in the lower half of the image, measured at about 13 degrees of latitude and roughly 9 to 18 degrees wide. That is the signature of the North Equatorial Belt (NEB), which runs from 7 to 17 degrees north — no other belt on Jupiter is so narrow, so dark and so sharply bounded against the Equatorial Zone. North is therefore down in this image. That is not a later rotation but the raw view through a Newtonian: it turns the image upside down, and nothing here was turned back.
The reddish oval therefore belongs to the southern hemisphere — and on that evening something specific was to be expected there. At the moment of exposure the central meridian stood at 184 degrees in System II (System I: 202 degrees). At the end of 2012 the Great Red Spot lay, according to the drift series, at roughly 185 to 190 degrees System II. It was thus practically facing Earth in that minute, and precisely at the center of the frame sits a reddish oval that carves a bay into the belt and behind which the band dissolves into turbulence. This combination — spot, belt bay, trailing disturbance — is the textbook signature of the Red Spot.
The identification is nonetheless not measured through to the end. The spot sits at 22 degrees south; the oval in the image measures about 28 degrees. The six-degree difference corresponds to roughly ten pixels — the same order as the spot itself and as the uncertainty of this measurement, because the dark polar regions blur the limb and with it the scale in the polar direction. That does not refute the identification, but neither does it prove it. What proof would take is a second stack from one of the later clips of the same night: in the 40 minutes up to the last Jupiter video the planet turns by 24 degrees, and a real cloud feature must visibly have moved toward the limb in that time.
Why that night belonged to Jupiter at all. Opposition fell on December 3, 2012, and the image was taken two days before: 4.069 astronomical units away, 48.4 arcseconds across, magnitude −2.7 — practically the maximum size of that apparition. Jupiter stood in Taurus, barely 5 degrees from Aldebaran, and culminated at 00:25; the sequence began 27 minutes later at an altitude of 60.6 degrees, air mass 1.15. At the same time a Moon 95 percent illuminated stood 56 degrees high. The night was lost for deep sky and ideal for planets and the Moon — and that is exactly how it continued: the thirteen Jupiter videos are followed from 01:36 by eleven lunar clips.
What the belts physically are. Jupiter has no surface. What we see is the top of the clouds in an atmosphere of mostly hydrogen and helium; its mean radius of 69,911 kilometers is eleven times Earth's diameter. The brown belts and bright zones are not stripes of paint but separate circulation systems, with powerful east-west jet streams running along their boundaries. This order is driven by the fastest rotation of any planet: 9 hours 55 minutes per turn.
The rotation visibly shapes the planet. Centrifugal force pushes Jupiter apart at the equator; its equatorial diameter is larger than the polar one by a factor of 1.069. In this image the disk is 239 pixels wide and 209 high — the flattening is visible to the naked eye. The measured ratio of 1.14 is not usable as a measurement, though: the poles are markedly darker than the Equatorial Zone, so any brightness-based edge detection cuts into the image earlier there.
And what the image cannot do. The theoretical resolving power of the 8-inch aperture is 0.68 arcseconds, that is 3.4 pixels of this image. It is not that sharp — focus and seeing visibly limit it to roughly three to five times that. Small eddies, white ovals, the fine structure of the belt edges and the internal shape of the Red Spot are not contained here and are not read into it either. The stack lowers noise and stabilizes what is there; it invents nothing that is not in the individual frames.
Acquisition and processing
Taken with a GSO 8″ Newtonian, 200/800 mm, a Tele Vue amplifier and an ALCCD planetary camera; the camera model is no longer documented. The source is an uncompressed 640 × 480 pixel 24-bit color AVI (rawvideo, BGR) with 1,695 frames at 15.1515 frames per second and a runtime of 111.87 seconds.
The amplification is measured, not remembered. Jupiter's equatorial diameter measures 239 pixels in the image and stood at 48.4 arcseconds that evening — that yields an image scale of 0.202 arcseconds per pixel. The focal length follows from it directly as soon as one assumes a pixel size: 3.75 µm gives 3,821 mm (4.8×, f/19), 5.2 µm gives 5,299 mm (6.6×, f/26), 5.6 µm gives 5,706 mm (7.1×, f/28). A 2.5× extension is therefore ruled out — it would require pixels 1.96 µm across, which planetary cameras of that period did not have; a round 5× would need 3.93 µm. The memory of the 5× Powermate is thus the variant that fits the recording. For the lunar panoramas of the same year the 2.5× Barlow is documented instead; that is no contradiction but the weaker amplification appropriate for the Moon. Incidentally: at 203 mm of aperture, 0.202″/pixel is exactly the classical optimum demanded by the rule of thumb "focal ratio ≈ 5 × pixel size in µm".
For the lucky imaging every frame was measured and sorted by the sharpness of the planet's internal detail. Of the best ten percent — 170 requested frames — 137 frames remained after centering and a subpixel phase-correlation check (median registration response 0.123); they were averaged. At no more than 66 ms of exposure per frame, that means under nine seconds of total exposure in the image. The stack is a 384 × 384 pixel crop of the original frames, not upscaled; the larger view comes purely from scaled display.
Derotation was demonstrably unnecessary. Jupiter turns by 1.13 degrees during the 111.87 seconds of the sequence. At the central meridian that amounts to 2.4 pixels of travel — well below the blur from seeing and focus. There was no field derotation, no AI detail synthesis and no reconstruction of cloud structure that is not there.
The gallery artifact is no longer the raw stack. The published file is the version of the linear stack post-processed in Adobe Photoshop 27.8: 16 bit, Adobe RGB, LZW. Compared with the raw stack it is sharpened (high-pass scatter 0.84 → 1.82) and tightened in its tonal values (background median 4 → 2, peak value 172 → 184); the pixel correlation with the original image is 0.983. The unprocessed linear 16-bit stack, together with the 25 and 50 percent versions and the measurement report, remains unchanged under Work/runs/jupiter-lucky-0-52-16-948-20260901/; all the measurements quoted here come from the published file.