아찔한달리기 구로건마 구로오피 아달

The white vertical arc at the left edge of the top panel is caused by sunlight filtering through Jupiter’s upper atmosphere; the white horizontal line in the left part of the figure is the main ring whose arms overlap in this foreshortened view. The next frame of the mosaic, taken at higher sensitivity to detect fainter material, shows (on the left part of this panel) the overexposed main ring and the halo (seen as material above and below the main ring) which is interior to the main ring and has become visible in this longer exposure. The middle panel, taken at twenty times the standard sensitivity, shows a tenuous horizontal stripe, which can be made out in the “10 times sensitivity panel also. In contrast to the main ring, which ends in a narrow elliptical tip, this “gossamer ring” ends abruptly (in the middle of the image) without changing its vertical thickness; the ring is also unusual in that its top and bottom edges are about twice as bright as the central region. Interestingly this ring is only seen to precisely the orbital distance of Amalthea, a small (mean radius of 85 km) Jovian moon, and has a half-thickness that is the same as Amalthea’s maximum excursion off Jupiter’s equatorial plane.

R09_satinc_full

Further to the right, using much higher sensitivities, another faint but wider stripe becomes visible. This last band is associated with Thebe, a Jovian moon with a mean radius of 50 km. The ring lies principally inside Thebe’s orbit and has a thickness like Thebe’s elevation above Jupiter’s equatorial plane. Given the position of Adrastea (in the equatorial plane at the periphery of the main Jovian ring), the main ring is likely derived from this small satellite (mean radius of 8 km).

jupiters-rings-2-nasa

The bottom rendition shows the orbital distances (in yellow) of the small satellites. The distances are given in units of Jovian radii; Jupiter’s radius is 71,398 kilometers (44,267 miles). Various components of the Jovian ring system are plotted as seen from the equatorial plane: the green band represents the positions of particles lost from Amalthea; the red band is material from Thebe.

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