What are shepherding moons? A shepherd moon
Shepherd moon
A shepherd 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 particles as a shepherd.
What is a shepherd moon?
Shepherd moon. The name is a result of the fact they limit the "herd" of the ring particles as a shepherd. Due to their gravitational effect, they pick up particles and deflect them from their original orbits through orbital resonance. This causes gaps in the ring system, such as the particularly striking Cassini Division,...
How did scientists discover the shepherd moons?
Discovery The existence of shepherd moons was theorized in early 1979. Observations of the rings of Uranus show that they are very thin and well defined, with sharp gaps between rings. To explain this, Goldreich and Tremaine suggested that two small satellites that were undetected at the time might be confining each ring.
What causes a shepherd moon to have rings?
Shepherd moon. Due to their gravitational effect, they pick up particles and deflect them from their original orbits through orbital resonance. This causes gaps in the ring system, such as the particularly striking Cassini Division, as well as other characteristic bands, or strange "twisted" deformation of rings.
Is Pandora a shepherd moon?
Shepherd moon. Prometheus (right) and Pandora (left) both orbit near Saturn's F ring, but only Prometheus is thought to act as a shepherd.
What is a shepherding moon and why are these important to Saturn?
Orbiting at the edges of some of the planet's main rings, or within gaps between them, these shepherd moons wield enough gravity to herd icy ring particles into place.
How is a shepherd moon different than a regular moon?
Shepherd satellites are small moons that orbit within, or just beyond, a planet's ring system.
What planets have shepherding moons?
Saturn. … moon, Prometheus, have been dubbed shepherd moons because of their influence on ring particles. During Voyager 1's flyby, the two bodies were discovered orbiting on either side of the narrow F ring, which itself had been found only a year earlier by Pioneer 11.
Why are shepherd moons important?
These moons are important because they are the "ring moons." They help the rings of Jupiter keep their form and sweep away any debris. The term for this function is called shepherd moons.
How many moons dies Saturn have?
53Read MorePlanet / Dwarf PlanetConfirmed MoonsTotalSaturn5382Uranus2727Neptune1414Dwarf Planets11 more rows•May 19, 2021
How did Saturn get its name?
Namesake. The farthest planet from Earth discovered by the unaided human eye, Saturn has been known since ancient times. The planet is named for the Roman god of agriculture and wealth, who was also the father of Jupiter.
What is shepherding in astronomy?
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 particles as a shepherd.
Does Saturn have shepherd moons?
Prometheus and Pandora, two of Saturn's more than 60 moons, flank the F ring on either side, weaving inside and outside the ring. These moons apparently act like shepherds, herding the flock of icy particles making up the F ring into a narrow band about 60 miles (100 km) wide.
Does Neptune have shepherd moons?
The rings of Uranus and Neptune are kept narrow by the action of shepherd moons, which "herd" the ring particles and keep them in a narrow range of orbits.
What is special about the F ring?
As for what might have caused the moonlets to become scarce, the team has a suspect: Saturn's moon Prometheus. The F ring encircles the planet at a special location, near a place called the Roche limit — get any closer to Saturn than this, and tidal forces from the planet's gravity tear apart smaller bodies.
Why do shepherd moons look different?
Shepherd moons are just ordinary moons: there is nothing special about them other than being in the right place to cause this effect. Shepherd moons orbit their parent planets close to either the inner or outer edge of a ring, and the effect of their gravity helps to maintain a sharply defined edge to the ring.
How did Uranus get its tilt?
Orbit and Rotation Uranus is the only planet whose equator is nearly at a right angle to its orbit, with a tilt of 97.77 degrees – possibly the result of a collision with an Earth-sized object long ago. This unique tilt causes the most extreme seasons in the solar system.
When was Shepherd Moons released?
Released: 1994. Shepherd Moons is the third studio album by Irish singer, songwriter and musician Enya, released on 4 November 1991 by WEA. After the unexpected critical and commercial success of her previous album Watermark (1988), Enya embarked on a worldwide promotional tour to support it. At its conclusion, she proceeded to write ...
How many copies of Shepherd Moons were sold?
By July 1994, seven million copies of Shepherd Moons had been sold worldwide. It sold close to one million copies in the United States each year from 1992 to 1996; in March 1996, it was certified quintuple platinum by the Recording Industry Association of America (RIAA) for shipment of five million copies.
Is Shepherd Moons a commercial success?
Shepherd Moons received generally positive reviews from critics and became a greater commercial success than Watermark. It went to number one on the UK Albums Chart and peaked at number seventeen on the Billboard 200 in the United States.
Overview
Prometheus acts as a shepherding moon, constraining the extent of the inner edge of Saturn's F Ring. Prometheus is extremely irregular and has visible craters — some up to 12.4 miles (20 kilometers) in diameter. However, it is much less cratered than its nearby neighbors Pandora, Janus and Epimetheus.
How Prometheus Got Its Name
Moons of Saturn were originally named for Greco-Roman Titans and descendants of the Titans. But as many new moons were discovered scientists began selecting names from more mythologies, including Gallic, Inuit and Norse stories.
What are the moons named after?
The modern names for Saturnian moons were suggested by John Herschel in 1847. He proposed to name them after mythological figures associated with the Roman titan of time, Saturn (equated to the Greek Cronus ). In particular, the then known seven satellites were named after Titans, Titanesses and Giants —brothers and sisters of Cronus. In 1848, Lassell proposed that the eighth satellite of Saturn be named Hyperion after another Titan. When in the 20th century the names of Titans were exhausted, the moons were named after different characters of the Greco-Roman mythology or giants from other mythologies. All the irregular moons (except Phoebe) are named after Inuit and Gallic gods and after Norse ice giants.
What are the irregular moons?
The largest of the irregular moons is Phoebe, the ninth moon of Saturn, discovered at the end of the 19th century.
How many moons were discovered before telescopic photography?
Before the advent of telescopic photography, eight moons of Saturn were discovered by direct observation using optical telescopes. Saturn's largest moon, Titan, was discovered in 1655 by Christiaan Huygens using a 57-millimeter (2.2 in) objective lens on a refracting telescope of his own design. Tethys, Dione, Rhea and Iapetus (the " Sidera Lodoicea ") were discovered between 1671 and 1684 by Giovanni Domenico Cassini. Mimas and Enceladus were discovered in 1789 by William Herschel. Hyperion was discovered in 1848 by W.C. Bond, G.P. Bond and William Lassell.
What are trojan moons?
Trojan moons are a unique feature only known from the Saturnian system. A trojan body orbits at either the leading L 4 or trailing L 5 Lagrange point of a much larger object, such as a large moon or planet. Tethys has two trojan moons, Telesto (leading) and Calypso (trailing), and Dione also has two, Helene (leading) and Polydeuces (trailing). Helene is by far the largest trojan moon, while Polydeuces is the smallest and has the most chaotic orbit. These moons are coated with dusty material that has smoothed out their surfaces.
How many moons does Saturn have?
Saturn has 82 moons with confirmed orbits that are not embedded in its rings – of which only 13 have diameters greater than 50 kilometers – as well as dense rings that contain millions of embedded moonlets and innumerable smaller ring particles.
Which moon is the smallest in the solar system?
Enceladus is one of the smallest of Saturn's moons that is spherical in shape—only Mimas is smaller —yet is the only small Saturnian moon that is currently endogenously active, and the smallest known body in the Solar System that is geologically active today.
How many moons did Voyager find?
The arrival of the Voyager spacecraft at Saturn in 1980–1981 resulted in the discovery of three additional moons – Atlas, Prometheus and Pandora, bringing the total to 17. In addition, Epimetheus was confirmed as distinct from Janus. In 1990, Pan was discovered in archival Voyager images.
Overview
Shepherd Moons is the third studio album by Irish singer, songwriter and musician Enya, released on 4 November 1991 by WEA. After the unexpected critical and commercial success of her previous album Watermark (1988), Enya embarked on a worldwide promotional tour to support it. At its conclusion, she wrote and rehearsed new material for her next album with her long time record…
Background and writing
In September 1988, Enya released her second studio album Watermark. It became an unexpected commercial success, charting around the world helped by its international top-ten hit, "Orinoco Flow". The album propelled Enya to worldwide fame and she spent much of the following year travelling worldwide to promote it through interviews, appearances, and performances. With such a length of time for promotion, Enya felt the priority was to return to the studio and record a new …
Recording
Shepherd Moons was recorded with new equipment purchased with the profits from Watermark. Much of the album was recorded at Aigle Studio, the recording studio in the Ryans' home, then located in Artane, a northern suburb of Dublin. However, as with her two previous albums, recording and production had to relocate elsewhere as the Aigle facility lacked the correct equipment to complete the final mix and mastering. The album was finished at SARM West Studi…
Songs
As with Watermark, the album title opens with an instrumental title track with wordless vocals. Its title, devised by Roma, refers to two inner satellite moons around Saturn discovered in 1980, Pandora and Prometheus, that "protect and preserve the rings very much like a shepherd guiding his flock". Enya also liked the title as the association with the moon "is quite romantic".
Release
Shepherd Moons was released on 4 November 1991 in the United Kingdom; its release in the United States followed on 19 November 1991 by Reprise Records. A promotional box set containing a CD and cassette of the album, plus a 14-page booklet autographed by Roma with her words on each track and lyrics, was released and limited to 1,000 copies.
The album became a greater chart success than Watermark, reaching number one on the UK Alb…
Reception
Shepherd Moons received generally positive reviews from music critics. In his review for The Washington Post, reviewer Mike Joyce praised Enya's vocals as "impressive" and "crystalline" that bring "unmistakable poignancy to much of the album". However, the tracks that focus on her piano playing, like "No Holly for Miss Quinn" and "Shepherd Moons", make the album "succumb to the usual new age doldrums". Barbara Jaeger gave a positive review for The Record. The three-year …
Personnel
Credits are adapted from the 1991 CD liner notes.
Musicians
• Enya – vocals, instruments, percussion, arrangement
• Andy Duncan – percussion on "Book of Days"
Footnotes
Notes
Citations