Motion of Saturn's Satellites
NOTE: Click on the image to view it at its highest resolution (315K).
Motion of Saturn's Satellites
This sequence of 100 sec exposures taken with HST's Wide Field and
Planetary Camera (WFPC2) in planetary mode on 10 August 1995 shows
three of the smaller satellites of Saturn, as well as the newly
discovered object 1995S5. Epimetheus is the smaller co-orbital
satellite and about 120 km in diameter, while 88 km diameter Pandora
is the outer shepherd satellite of the narrow F Ring. 1995S5 appears
as a faint smudge in the plane of the rings. The outward orbital
motions of Pandora and 1995S5 are apparent, as are the displacements
of Epimetheus and Mimas to the north and south of the ring plane, due
to the slight inclinations of their orbits relative to Saturn's
equator. The brightness of 1995S5 is consistent with an object of
diameter 50 km or less.
These images were obtained approximately one hour before the Earth
crossed Saturn's ring plane and an 8922 A methane band filter was used
to reduce the scattered light from the planet. An average of several
earlier frames was subtracted from each image to remove the edge-on
rings, and so reveal the fainter satellites. Some residual artifacts
of this subtraction process are visible. Structure on the planet is
due to cloud features which changed position as the planet rotated.
Unlabelled bright spots and streaks are due to cosmic ray hits on the
detector.
Credit: Phil Nicholson (Cornell University), Mark Showalter
(NASA-Ames/Stanford) and NASA
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