Judy: "The Great Red Spot is still kinda great, but it's getting smaller and smaller as time wears on. At some point, it may just be a regular red spot. Still, it remains a striking feature, and it is nice that it was facing the telescope when these observations were taken."
"Bright, icy Europa is just about finished transiting the impressively sized planet and can be seen near the top."
The Great Red Spot is a persistent high-pressure region in the atmosphere of Jupiter, producing an anticyclonic storm 22° south of the planet's equator. It has been continuously observed for 188 years, since 1830. Earlier observations from 1665 to 1713 are believed to be of the same storm; if this is correct, it has existed for at least 350 years. Such storms are not uncommon within the turbulent atmospheres of gas giants.
Europa is the smallest of the four Galilean moons orbiting Jupiter, and the sixth-closest to the planet. It is also the sixth-largest moon in the Solar System. Europa was discovered in 1610 by Galileo Galilei.
Slightly smaller than Earth's Moon, Europa is primarily made of silicate rock and has a water-ice crust and probably an iron–nickel core. It has a tenuous atmosphere composed primarily of oxygen. Its surface is striated by cracks and streaks, whereas craters are relatively rare. In addition to Earth-bound telescope observations, Europa has been examined by a succession of space probe flybys, the first occurring in the early 1970s.
Europa has the smoothest surface of any known solid object in the Solar System. The apparent youth and smoothness of the surface have led to the hypothesis that a water ocean exists beneath it, which could conceivably harbor extraterrestrial life. The predominant model suggests that heat from tidal flexing causes the ocean to remain liquid and drives ice movement similar to plate tectonics, absorbing chemicals from the surface into the ocean below. Sea salt from a subsurface ocean may be coating some geological features on Europa, suggesting that the ocean is interacting with the seafloor. This may be important in determining if Europa could be habitable.
(Source: Wikipedia)
Technical details:
This image represents how Jupiter looked on 2017-07-11 at 09:47:16 UTC. It is composed using three images which were taken a few minutes apart. Individual frames were warped to align cloud tops and Europa with the Red (F631N) channel. This is an approximately visible light image.
Data from the following proposal comprise this image:
Wide Field Coverage for Juno (WFCJ): Jupiter's 2D Wind Field and Cloud Structure
https://archive.stsci.edu/proposal_search.php?mission=hst&id=14661
Red: WFC3/UVIS F631N
Green: WFC3/UVIS F502N
Blue: WFC3/UVIS F395N
Credit: NASA/ESA
Processing & Caption: Judy Schmidt
Release Date: July 17, 2018
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