Juno at Perijove-7 (Part 2): The Great Red Spot
The JunoCam team have posted the images from Perijove-7 (PJ7), including the much-anticipated closeups of the Great Red Spot (GRS). [This is a revised and expanded version of the item which we posted originally.]
Figure 6 is a compilation of the four images, using the projected versions from the JunoCam web site, which do not have full resolution. Full-resolution versions by Gerald Eichstädt are available on the web site as described in Part 1. Figure 7 is part of the closest full-res image, taken from 9866 km above the GRS, which is the highest-resolution image ever taken of it, surpassing those from Voyager.
Gerald has combined these images into a spectacular synthetic movie of the fly-over, at: https://www.youtube.com/watch?v=1zPsYP8h9EE&feature=youtu.be
The animation below shows the circulation of the GRS from the four images, which were processed and projected to a common viewpoint by Gerald. They were then unsharp-masked, intensity-adjusted, and slightly rotated and stretched to improve their registration, though slight distortions remain. They cover only 11.7 minutes in total, during which the outer parts of the GRS rotate by about 1 degree.
This can be compared with a ground-based animation, from amateur Earth-based images, which we posted at: https://www.britastro.org/node/10663
The time interval is probably too short to see eddying or other deviations from the overall circulation, but the patterns in the clouds suggest vigorous dynamics, as in images by Hubble over the last few years. The unprecedented resolution also reveals clusters of little shadow-casting clouds, and a train of small-scale waves along the northern edge of the GRS (Figure 8); these have never before been seen in the GRS. The shadow-casting clouds appear orange, unlike the white ones which JunoCam has discovered in many other regions of the planet; this is probably because they lie below the orange haze that gives the GRS its colour.
Small versions of the figures are shown below, and the full-size versions can be downloaded here:
JNCE_2017192_07C00060_Gerald-prelim_v3-usm.jpg
Fig8_PJ07_060_clouds&waves-in-GRS.jpg
FIGURE 6:
FIGURE 7 (Please download image from link given above).
FIGURE 8:
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