Image of Jupiter's space environment, or magnetosphere, taken with the innovative energetic neutral atom (ENA) imaging technique by the Magnetospheric Imaging Instrument on NASA's Cassini spacecraft as it flew past Jupiter in early 2001 at a distance of about 6 million miles (10 million kilometers) from the planet. The field-of-view represented by the image is 30 degrees on the horizontal axis and 36 degrees on the vertical axis. The color is coded according the number of ENA counts observed within each 1.4-by-1.9 degree pixel over a 15-hour observing period, with red representing the highest number of counts and light blue representing the background counts.
The central object represents ENA emissions from Jupiter itself, a consequence of the impingement of energetic ions from Jupiter's magnetosphere onto the upper atmosphere. The two outer objects represent ENA emissions from a massive donut-shaped gas cloud — or torus — that shares an orbit with Jupiter's moon Europa, at a distance from Jupiter of more than 400,000 miles (more than 650,000 kilometers).
The near-Europa emissions are "dot like" because the torus is viewed edge-on. The image is brightest where the imager's line-of-sight passes through the greatest volume of the gas torus.
Credit: NASA/Jet Propulsion Laboratory/Johns Hopkins University Applied Physics Laboratory.
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