Saturn's Moons

Saturn: Moons

Color photo of Saturn and it's rings and the moons Epimetheus and Titan.
Cassini delivers this stunning vista showing small, battered Epimetheus and smog-enshrouded Titan, with Saturn's A and F rings stretching across the scene.

Saturn, the sixth planet from the sun, is home to a vast array of intriguing and unique worlds. From the cloud-shrouded surface of Titan to crater-riddled Phoebe, each of Saturn's moons tells another piece of the story surrounding the Saturn system.

We've discovered a total of 53 confirmed moons and another 8 provisional moons (for a possible total of 61 moons).

Christiaan Huygens discovered the first known moon of Saturn. The year was 1655 and the moon was Titan. Giovanni Domenico Cassini made the next four discoveries: Iapetus (1671), Rhea (1672), Dione (1684), and Tethys (1684). Mimas and Enceladus were both discovered by William Herschel in 1789. The next two discoveries came at intervals of 50 or more years -- Hyperion (1848) and Phoebe (1898).

As telescopic resolving power increased through the 19th century, Saturn's family of known moons grew. In 1966 Epimetheus and Janus were discovered. By the time Cassini-Huygens was launched in 1997, Saturn's moon count had reached 18. The number of known moons soon increased with high-resolution imaging techniques used on ground-based telescopes. The Cassini mission has discovered several more moons since its arrival at Saturn.

We've discovered a total of 53 confirmed moons and another 8 provisional moons (for a possible total of 61 moons).

Each of Saturn's moons bears a unique story. Two of the moons orbit within gaps in the main rings. Some, such as Prometheus and Pandora, interact with ring material, shepherding the ring in its orbit. Some small moons are trapped in the same orbits as Tethys or Dione. Janus and Epimetheus occasionally pass close to each other, causing them to periodically exchange orbits.

Here's a sampling of some of the unique aspects of the moons:

  • Titan is so large that it affects the orbits of other near-by moons. At 5,150 km (3,200 miles) across, it is the second largest moon in the solar system. Titan hides its surface with a thick nitrogen-rich atmosphere. Titan's atmosphere is similar to the Earth's atmosphere of long ago, before biology took hold on our home planet. Titan's atmosphere is approximately 95% nitrogen with traces of methane. While the Earth's atmosphere extends about 60 km (37 miles) into space, Titan's extends nearly 600 km (ten times that of the Earth's atmosphere) into space.
  • Iapetus has one side as bright as snow and one side as dark as black velvet, with a huge ridge running around most of its dark-side equator.
  • Phoebe orbits the planet in a direction opposite that of Saturn's larger moons, as do several of the more recently discovered moons.
  • Mimas has an enormous crater on one side, the result of an impact that nearly split the moon apart.
  • Enceladus displays evidence of active ice volcanism: Cassini observed warm fractures where evaporating ice evidently escapes and forms a huge cloud of water vapor over the south pole.
  • Hyperion has an odd flattened shape and rotates chaotically, probably due to a recent collision.
  • Pan orbits within the main rings and helps sweep materials out of a narrow space known as the Encke Gap.
  • Tethys has a huge rift zone called Ithaca Chasma that runs nearly three-quarters of the way around the moon.
  • Four moons orbit in stable places around Saturn called Lagrangian points. These places lie 60 degrees ahead of or behind a larger moon and in the same orbit. Telesto and Calypso occupy the two Lagrangian points of Tethys in its orbit; Helene and Polydeuces occupy the corresponding Lagrangian points of Dione.
  • Sixteen of Saturn's moons keep the same face toward the planet as they orbit. Called "tidal locking," this is the same phenomenon that keeps our Moon always facing toward Earth.
SATURN'S MOONS
PROVISIONAL MOONS

Rough Notes:

Saturn’s moons Tethys and Dione Credit: NASA/JPL


Jun 18, 2007
Saturn's Electric Moons

We have long contended that "geysers" on Saturn’s moon Enceladus are part of the electrical circuitry of Saturn. Now NASA has announced new evidence that Saturn’s moons Tethys and Dione are part of this same circuitry.

In previous Thunderbolts Pictures of the Day, we presented several examples of how Jupiter’s highly charged, electric environment creates features on the planet’s small moon Io that cannot be adequately explained by conventional scientists. The observed phenomena are deemed “mysterious,” and they appear to contradict the theory of an electrically neutral solar system. Similarly, Jupiter’s moons Ganymede and Europa electrically influence the gas giant’s plasmasphere.

The Cassini-Huygens mission was launched from Cape Canaveral on October 15, 1997. Its primary mission was the exploration of the Saturnian system, including its atmosphere, itsrings, its magnetosphere and a number of its moons. Although Titan was the highest priority, the mission has brought many surprising discoveries, and among the greatest of these have been the icy plumes erupting from the south polar region of Saturn’s moon Enceladus.

The image above shows two more of Saturn’s moons, Tethys (left) and Dione (right). Both are now known to be actively interacting with the electric field of their parent body.

In a June 13, 2007 European Space Agency release it was announced that the two moons are “flinging great streams of particles into space.” The discovery was made by the Cassini Plasma Spectrometer, when data from Saturn revealed that the ionized gas (actually a plasma) surrounding the planet was trapped within its magnetic field and (to use NASA’s archaic expression) being “squashed into a disc.”

The language used by NASA scientists continues to amuse plasma experts. The ESA release notes that Saturn rotates at a very high speed for its size and mass, and from this the investigators deduced that the ionized material is forced out mechanically. “Just like a child on a fast-spinning merry-go round, the trapped gas feels a force trying to throw it outwards, away from the centre of rotation.” According to the report, the instruments found that when the material is removed more tenuous and hotter plasma enters the empty regions within the field. That additional plasma has been traced to the active moons. (“Tethys and Dione as sources of outward-flowing plasma in Saturn’s magnetosphere”: J. Burch, J. Goldstein, W. Lewis, D. Young, A. Coates, M Dougherty and N. André. Nature, June 14, 2007).

As in other instances of electrical discoveries in planetary environments, NASA scientists can only see internal pressure, centrifugal force, and “gas flow.” Of course, they are aware that plasma makes up more than 99% of the visible universe, but they have yet to consider the role of charge distribution within the plasma of space. Instead, a charge-neutral solar system is held up as the sine qua non of theoretical speculation.

In contrast, electrical theorists argue that Saturn moves within the plasmasphere of the Sun and interacts with the Sun’s electric field. Planets and moons in the solar system are charged bodies. They are not isolated in “empty” space, but “converse” electrically with each other. Because Enceladus, Dione and Tethys all move within the plasmasphere of Saturn, it is only to be expected that they would transact electrically with their primary.

The researchers who make up the Thunderbolts team have been asserting for many years that plumes, geysers, and jets rising from the moons of gas giants are plasma discharges. NASA’s investigators seem unable to comprehend the observational evidence, preferring to describe the activity on these moons as forms of “volcanism.” That is why they were caught by surprise when the Galileo mission revealed that the plume of Prometheus on Io had moved more than 80 kilometers (50 miles)!

The simplest, most straightforward explanation of the charged particles spewing from the icy moons of Tethys and Dione is electric discharge, so there is no need to conjure implausible internal dynamics to account for these remarkable events. We predict, therefore, that investigation over time will show that the active sources of charged particle streams from Enceladus, Tethys, and Dione all move across the surface.

By Stephen Smith

Coming Friday, June 22: "Triton's Ice Geysers"

Planetary Double Layers

  

Canyons in Titan's southern latitudes

Canyons in Titan's southern latitudes. Credit: NASA/JPL

Nov 03, 2011

Was Titan born from electrical parturition?

Considering the variety of Saturn’s moons, it would be difficult to identify them as members of the same family. They vary in size, chemical composition, temperature, and appearance. However, superficial appearances are often misleading when it comes to overall qualities or characteristics. Powerful electromagnetic connections with their giant parent planet indicate they share common traits.

A recent press release states that a gravity map of Titan, created by monitoring changes in the Cassini orbiter’s speed as it flew by the giant moon between February 2006 and July 2008, shows that its interior is a mixture of rock and ice with no layering. The orbital variations were measured by the Earth-based Deep Space Network as Titan’s gravity “pushed and pulled” Cassini in its flight path. Analyzing those gravitational tics provides data for computer models of Titan’s core.

Since the variations in gravity suggest a variation in density, and that variation is so subtle, there are no “mascons” of rock distributed through Titan’s body as there are inside Earth’s Moon. Instead, the rocks and ice are thought to be compacted into a relatively homogeneous interior structure.

As written in previous Picture of the Day articles, many of Titan’s anomalies can be explained if a youthful aspect is considered. Titan might be only a few thousand years old and not the billions of years required by conventional astrophysics. If that is the case, then the presence of its dense atmosphere, lacking a mechanism for replenishment, can be attributed to that youth. Since Titan is relatively young, its atmosphere is not in equilibrium. It is losing methane at a measurable rate. That atmospheric loss requires methane production somewhere on or in the moon’s body if it is ancient.

The canyons and “rilles” on Titan’s surface are thought to be “drainage channels” from the methane rains that must periodically fall to feed the “rivers,” although no precipitation was detected. However, in an Electric Universe the canyons are blast marks etched into Titan’s surface from tremendous lightning discharges. They point to the moon’s savage electrical birth. Their dendritic forms are called Lichtenberg figures, which look like some river systems on Earth.

That recent electrical birth, possibly resulting from a double layer overload within Saturn, also explains Titan’s homogeneous core. Electric Universe theory proposes that the progeny of stars or planets are not all born at the same time as the parent. They are born hierarchically at intervals, and typically from within the parent. They are ejected.

If Titan was ejected from Saturn in a paroxysm, then its atmosphere and surface features are the results of that catastrophic event. Its interior could be electrically charged, either from a continuous circuit connection with Saturn or because it retains a remanent discharging current flow. Possibly both. The small effects on Cassini could be electrical in nature.

Are concepts of a “slushy core” or a “rocky interior” outdated premises? Do the deep places of planets and moons possess double layers? If so, the “gravitational effects” on Cassini could indicate that Titan is exerting an electric force on the spacecraft.

Stephen Smith