On the cause of the discrepancy between groundbased and spaceborne lightcurves of Ganymede and Callisto in the <Emphasis Type="Italic">V</Emphasis> band
1.Research Institute, Crimean Astrophysical Observatory,National Academy of Sciences of Ukraine,Nauchnyi, Crimea,Ukraine;2.Infokholding Company,Simferopol’, Crimea,Ukraine
Abstract:
Properties of the surfaces of Jupiter’s satellites—Ganymede and Callisto—are shortly described. Their images acquired in space
missions are shown. Causes of the discrepancy between orbital lightcurves of the satellites obtained from the earth and spaceborne
maps of the satellites are considered. The groundbased observations were carried out under phase angles of solar illumination
ranging from 0° to 12°, and the maps were built from images acquired from spacecraft in a wide interval of solar phase angles.
We suggest that the main cause of the discrepancies between the lightcurves is the coherent backscattering effect observed
only at small phase angles of the sun.