This comparison of visible light (blue) and far-ultraviolet (FUV) images of Jupiter taken with the Wide Field Planetary Camera-2 (WFPC-2) on NASA's Hubble Space Telescope show how the appearance of the planet and of comet Shoemaker-Levy 9 impact sites differ at these two wavelengths (1400-2100 and 3100-3600 Angstroms). The images taken 20 minutes apart on July 17,1994 (around 19:00 UT), show the impact sites on the southern hemisphere, from left to right, of comet fragments C, A, and E, about 12, 23, and 4 hours after each collision. Jupiter's satellite 10 is seen crossing above the center of the disk, and the famous Great Red Spot is near the eastern limb.
While visible light reflects off the top of Jupiter's cloud decks, ultraviolet light doesn't penetrate any deeper than Jupiter's stratosphere and higher altitude levels (hundreds of kilometers above the cloud tops). The grainy appearance of Jupiter in the FUV is due to the darkness of the planet at this wavelength. Jupiter's aurora can be seen around the north and south poles where the atmosphere appears dark due the presence of hazes. These emissions are produced when energetic charged particles from Jupiter's magnetic field collide with molecular hydrogen in the upper atmosphere.
In the visible image, the impact sites appear as localized dark spots with diffuse halos. In the ultraviolet image the impact regions appear darker and more extended, because the FUV is more sensitive to smaller amounts of particles and/or that the horizontal winds in the upper atmospheric levels may be faster. The dark appearance is due to the presence of enhanced amounts of UV-absorbing molecules, scattering hazes and dust. This material should be a combination of gases from Jupiter's lower atmosphere as well as comet volatiles and impact by-products that were carried up from deeper in Jupiter's atmosphere and deposited into the stratosphere and thermosphere. Material should also have been deposited from ablation of the fragments and dust during entry.
Tracking the motions with WFPC-2 FUV images of the dark comet fragment "clouds" throughout the impact period should reveal for the first time the magnitude and direction of the high altitude winds on Jupiter. The Jovian auroral emissions will also be monitored with both WFPC-2 and the Faint Object Camera (FOC) to determine if the associated processes are affected by the comet's passage through the magnetosphere or changes in the upper atmosphere.
Credits
John Clarke, University of Michigan and NASA| About The Object | |
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| Object Name | Jupiter, Comet P/Shoemaker-Levy 9 |
| About The Object | |
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| Object Name | A name or catalog number that astronomers use to identify an astronomical object. |
| Object Description | The type of astronomical object. |
| R.A. Position | Right ascension – analogous to longitude – is one component of an object's position. |
| Dec. Position | Declination – analogous to latitude – is one component of an object's position. |
| Constellation | One of 88 recognized regions of the celestial sphere in which the object appears. |
| Distance | The physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs. |
| Dimensions | The physical size of the object or the apparent angle it subtends on the sky. |
| About The Data | |
| Data Description |
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| Instrument | The science instrument used to produce the data. |
| Exposure Dates | The date(s) that the telescope made its observations and the total exposure time. |
| Filters | The camera filters that were used in the science observations. |
| About The Image | |
| Image Credit | The primary individuals and institutions responsible for the content. |
| Publication Date | The date and time the release content became public. |
| Color Info | A brief description of the methods used to convert telescope data into the color image being presented. |
| Orientation | The rotation of the image on the sky with respect to the north pole of the celestial sphere. |
