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Daphnis is an inner satellite of
May 6, 2005 (discovery) Daphnis is about 8 kilometers in diameter, and orbits the planet in the Keeler Gap within the A ring.
The discovery of Daphnis was announced by th
Cassini Imaging Science Team
on May 6, 2005.
/ref> The discovery images were taken by the '' Cassini'' probe over 16 min on May 1, 2005, from a time-lapse sequence of 0.180 second narrow-angle-camera exposures of the outer edge of the A ring. The moon was subsequently found in 32 low-phase images taken of the F ring on April 13, 2005 (spanning 18 min) and again in two high-resolution (3.54 km/
Daphnis orbits within the Keeler gap in Saturn's rings. As it orbits, it creates gravitational ripples on the edges of the gap as ring particles are attracted toward the moon and then fall back down toward the ring. The waves made by the moon in the inner edge of the gap precede it in orbit, while those on the outer edge lag behind it, due to the differences in relative orbital speed. In a photograph taken on January 18, 2017, a tendril of ring particles can be seen to extend toward the moon; according to JPL, "this may have resulted from a moment when Daphnis drew a packet of material out of the ring, and now that packet is spreading itself out."
Discovery images of Daphnis at the CICLOPS web site (includes a movie of the moon's ripple effect)
*
Photos of Daphnis from the CICLOPS web site
{{DEFAULTSORT:Daphnis (Moon) Moons of Saturn 20050506 Moons with a prograde orbit
Saturn
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...
. It is also known as ; its provisional designation was .C.C. Porco, et al., IAUC 8524: ''S/2005 S 1''May 6, 2005 (discovery) Daphnis is about 8 kilometers in diameter, and orbits the planet in the Keeler Gap within the A ring.
Naming
The moon was named in 2006 afterDaphnis
In Greek mythology, Daphnis (; grc, Δάφνις, from , ''daphne'', "Bay Laurel") was a Sicilian shepherd who was said to be the inventor of pastoral poetry.
Family
According to tradition, he was the son of Hermes and a nymph, despite which ...
, a shepherd, pipes player, and pastoral poet in Greek mythology
A major branch of classical mythology, Greek mythology is the body of myths originally told by the ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the origin and nature of the world, the lives and activities o ...
; he was descendant of the Titans
In Greek mythology, the Titans ( grc, οἱ Τῑτᾶνες, ''hoi Tītânes'', , ''ho Tītân'') were the pre-Olympian gods. According to the ''Theogony'' of Hesiod, they were the twelve children of the primordial parents Uranus (Sky) and Gai ...
, after whom the largest moons of Saturn are named. Both Daphnis and Pan, the only other known shepherd moon
A shepherd moon (also herder moon or watcher moon) is a small natural satellite that clears a gap in planetary-ring material or keeps particles within a ring contained. The name is a result of the fact they limit the "herd" of the ring particle ...
to orbit within Saturn's main rings, are named for mythological figures associated with shepherd
A shepherd or sheepherder is a person who tends, herds, feeds, or guards flocks of sheep. ''Shepherd'' derives from Old English ''sceaphierde (''sceap'' 'sheep' + ''hierde'' ' herder'). ''Shepherding is one of the world's oldest occupations, ...
s.
Discovery
Before it was photographed, the existence of a moon in Daphnis's position had already been inferred from gravitational ripples observed on the outer edge of the Keeler gap.
The discovery of Daphnis was announced by thCassini Imaging Science Team
on May 6, 2005.
/ref> The discovery images were taken by the '' Cassini'' probe over 16 min on May 1, 2005, from a time-lapse sequence of 0.180 second narrow-angle-camera exposures of the outer edge of the A ring. The moon was subsequently found in 32 low-phase images taken of the F ring on April 13, 2005 (spanning 18 min) and again in two high-resolution (3.54 km/
pixel
In digital imaging, a pixel (abbreviated px), pel, or picture element is the smallest addressable element in a raster image, or the smallest point in an all points addressable display device.
In most digital display devices, pixels are the ...
) low-phase images taken on May 2, 2005, when its 7 km disk was resolved.
Orbit
Theinclination
Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object.
For a satellite orbiting the Ea ...
and eccentricity of Daphnis's orbit are very small, but distinguishable from zero. Both, particularly the inclination, are significantly greater than those of Pan (the larger moonlet which forms the Encke Gap). Daphnis's eccentricity causes its distance from Saturn to vary by ~9 km, and its inclination causes it to move up and down by ~17 km. The Keeler Gap, within which Daphnis orbits, is about 42 km wide.
Effect on Saturn's rings
Daphnis orbits within the Keeler gap in Saturn's rings. As it orbits, it creates gravitational ripples on the edges of the gap as ring particles are attracted toward the moon and then fall back down toward the ring. The waves made by the moon in the inner edge of the gap precede it in orbit, while those on the outer edge lag behind it, due to the differences in relative orbital speed. In a photograph taken on January 18, 2017, a tendril of ring particles can be seen to extend toward the moon; according to JPL, "this may have resulted from a moment when Daphnis drew a packet of material out of the ring, and now that packet is spreading itself out."
Physical characteristics
On January 18, 2017, Daphnis was photographed from a sufficiently close distance to reveal its shape. The moon was discovered to be an irregularly-shaped object with a mostly smooth surface, a few craters, and anequatorial ridge
Equatorial ridges are a feature of at least three of Saturn's moons: the large moon Iapetus and the tiny moons Atlas and Pan. They are ridges that closely follow the moons' equators. They appear to be unique to the Saturnian system, but it is ...
.
References
External links
Discovery images of Daphnis at the CICLOPS web site (includes a movie of the moon's ripple effect)
*
Photos of Daphnis from the CICLOPS web site
{{DEFAULTSORT:Daphnis (Moon) Moons of Saturn 20050506 Moons with a prograde orbit