In a discussion concerning the facts surrounding the great "Lord of the Rings", I can only relate to this, by revealing those facts through the many observation that I have made of this magnifiscent planet through the years.
The observations that I have made with the 14 inch (356mm) Cassegrain, and my 24 inch (600mm) reflector, reveal the intricate patterns in the cloud belts of Saturn's surface. Although, my view of Saturn's surface is not as clear as that of Jupiter's, or as complex, it is however very beautiful none the less. When using our fourteen inch Cassegrain working at around 200x, there appears to be three major ring divisions that are visible in the telescope. They are labeled from outer most to the inner most as the A, B, and C rings. Between the A and the B rings there is approximately two thousand nine hundred miles of what appears as open space, called the Cassini division. This gap appears in telescopes as the very dark ring that dominates the view in telescopes as small as three inches in diameter.
Although this gap is quite dim in smaller telescopes, it does show up well, and quite obvious. However this division is more evident in telescopes with apertures of ten inches (250mm) and above. This gap is most prominent when the rings are fully open in all there magnificence. The middle B ring is the widest, and the brightest of the three rings, and overwhelms the C ring which is known as the "Crepe ring", the C ring is even more predominant in larger telescopes such as my 24 inch reflector, or our 14 inch Cassegrain, but can also been seen in smaller scopes, but not as beautiful, or detailed as it can be seen in larger scopes, such as those I have described.
The orb of the planet has equatorial bands that in the Cassegrain appear to number in the range of four. There are two large bands in the center of the orb, and two smaller ones situated on either side of the two center ones. The color of the cloud bands, appear to be an orange color against the planets surface, which appears as a yellow green in color. The rings however appear to range from blue to varying shades of purple.
THE RINGS of SATURN
The physical make up the rings of Saturn has remained a mystery since the first observations made by Galileo. The riddle of their creation and existence has puzzled astronomers for centuries. Not to mention they have been one of the reason for great voyages to this magnificent lord of the rings.
Saturn has at one time or another been the target of every telescope that has been conceived since Newton. As the technology of telescopes evolved through the years, they have been used by astronomers to dissect and scrutinize Saturn for every detail that could be resolved to satisfy their curiosity, as we shall soon see.
In 1850 a man by the name of William Cranch Bond armed with Harvard's new 15 inch refractor, discovered Saturn's Crepe ring. Subsequent observations by his son George Phillips Bond, brought about a theory that the slow changing in the appearance of these rings meant that the rings must be of a liquid nature rather than of a solid nature.
Later in the year 1857, a young mathematician by the name of James Maxwell proved in his essay to Cambridge University, which showed that the existence of the rings in either a solid state or a liquid state just simply could not be possible. Maxwell proved that the rings were made up of millions of minute particles that moved within independent orbits within the equatorial plane of the rings.
Maxwell further proved how equations deduced from his own mathematical theories, could account for every observation of Saturn made to date, with the exception of one. The theories set forth by Maxwell were so straight forward they were accepted immediately, by the scientist of his time.
Although Maxwell's theory could not sufficiently explain why the outer rings revolved at a slower rate than the inner rings, this answer would come in the year 1895 when a theory would be introduced by James Keeler (of the Keeler gap fame), his answer would explain this phenomena through a combination of observations and mathematical equations.
The Keeler gap, which is located on the outer edge of the A ring is a very small gap, which is approximately 35 kilometers wide bordered on two sides by areas comprised of lower density rings. The darker lines, seen in orbiter images close to the Keeler gap are made up of a denser material that is as of yet unknown, but probably consisting of thick dust particles.
TRAVERSING THE RINGS
The rings of Saturn are wide but very thin, the brightest parts of the ring that you see in the telescope are around 45,000 miles wide, and only about a mile thick, that's the reason they seem to disappear, when viewed from edge on. Saturn has god only knows how many rings. The images sent back to Earth reveal a world dominated by thousands of rings that surround Saturn like a glorious crown. Each of the rings contains mysteries that are unique unto themselves, such as the intertwining ribbons of one ring, to the rippled looks of another.
The dominant rings you see in your telescope probably formed from a moon that was drawn into Saturn's gravitational field. This moon was torn apart in the great tidal forces that it encountered there, which in turn was probably involved in collisions with other moons - or both. Evidence of these massive collisions are seen in the observations made of the moons Mimas and Hyperion, who both display craters that were capable of destroying the moons.
Researchers have stated that the total mass of Saturn's rings could produce a moon the size of Mimas, which indicates that the origin of the rings was more than likely produced by a huge tidal disruption of a large moon by the gravitational field of Saturn as I mentioned earlier. Other theories of the rings origins, state that the rings may have always been there, but were unable to form a moon or moons as large as ours because of the strong influence of Saturn's gravity.
The Shepards along the way
Looking at the rings face on brings into view the entire menagerie of rings, which are revealed in all their splendor. Starting at the almost invisible outer E ring (which was created, and is controlled by the moons Mimas, Enceladus, Tethys, and Dione), and moving inward we find the G ring, which is held in check by the moons Epimetheus and Janus, and said to also be influenced by Mimas. There has also been a recent discovery made by the Cassini orbiter that involves the discovery of a ring arc that is located just inside the thin G ring. This arc is thought to be quite rare indeed due to the fact that ring resonances usually disperse these arcs into other rings or they become part of an already existing ring.
Crossing the dark void left by these two moons we come to the very small F ring and the Keeler gap, which is controlled by the three moons Prometheus, Atlas, and Pandora. Of the three moons affecting the F ring the moon Prometheus is the dominate of the three sweeping the F ring clear about every 14 to 15 hours, as it comes in close proximity to the ring.
As Prometheus approaches the F ring its gravitational field causes the ring to split into long drawn out strands, and by 2009 it should put on quite a show because it will plow deeper in to the F ring raising all kinds of havoc.
Space probes have discovered an unusual amount of atomic oxygen in large concentrations along the perimeter of the rings, which is probably due to collisions of smaller moons and associated debris, ranging in size from small particles to boulders the size of houses. Radio waves sent through the rings to measure the ring density, have produced results conducive to a much thicker B ring than previously thought, much thicker than either the A ring or the highly perturbed C ring. This is a strong indication that the B ring may have experienced a recent impact between two or more small moons.
Now we cross the smaller dark void of the Encke division which is swept clean by the moon Pan. The Encke division is about 325 kilometers (200 miles) wide; although from a distance it appears empty, orbital images reveal a region that while even under the shepherding effects of the moon Pan, there are areas found here that are filled by ultra thin rings. The flanking edges of the Encke gap are distorted by Pans gravitational pull, which stretches them out into oddly shaped forms that have their leading edges carved into scallops and wavy patterns.
Now we enter the widest portion of the A ring. In the A ring we find the influence of moons so small we can not see them at the time of this writing, but know they are there because of the reaction of the rings to their presence. Any time a moon orbits above or below the ring plane the material that makes up the ring will react to the fluctuations in the changing gravitational fields. These changes cause the ring material to twist up or form wavy patterns that in some cases can and will block light resulting in dark strange shaped rings. So many questions are still unanswered, but we hope that the orbiters in place can make a profound effort at solving these in the near future.
Now we will cross the A ring and enter the dark void of the Cassini division. The Cassini division is the 4,700km gap that divides the A ring from the B ring. The Cassini division is quite large when compared to the smaller Encke division which measures in at a measly 200 miles across.
The Cassini division owes its existence to the fact that there is a profound 2:1 orbital resonance here between the moon Mimas, whose orbital time around Saturn is 22.6 hours, compared to the orbital time of the ring debris which is a little over 11 hours.
As of late scientist reviewing the Cassini orbiter images, have discovered what appears to be clumps of material the size of football fields imbedded in the rings. So far nothing this small has ever been discovered. The one dimensional images provided by the Cassini orbiter, do not reveal weather the clumps are solid objects or just cloud like gatherings of material.
THE MOONS of SATURN
Saturn is orbited by many moons, eleven of which are at least 120 miles across, the rest are probably around eleven miles across, or less. Saturn's moons are scattered across a large distance. The moon nearest Saturn is about 45,000 miles above the planets cloud tops. Saturn's farthest moon is Phoebe, which is about 6,540,000 miles from the cloud tops of Saturn.
So, as you can see the moons of Saturn come in different sizes. Take for example Enceladus, which is about 310 miles across, and was imaged in Nov 27, 2005 showing volcanoes erupting ice high above the surface of Enceladus, like great geysers. These eruptions are credited with much of the ice particles that fill the E ring and are subsequently swept up by the other moons. These ice particles are said to be the origin of the mysterious coating reported to exist on the many of the other moons that inhabit the E ring, such as Dione and Rhea.
Iapetus which is around 900 miles across is the second farthest from Saturn. For some strange reason Iapetus surface is two toned in color (white on one side and dark on the other).For a good while this two tone feature was a mystery to researchers until it was discovered through orbital data, that the dark side tends to absorb more radiation from the Sun, which heats the dark side more than the light side. This thermal heating tends to vaporize the ice, which migrates to the colder bright side, resulting in the two tone look of Iapetus that we see today.
Now Saturn's moon Tethys is around 650 miles across, and sports a very large crater on one side measuring 250 miles in diameter. In addition to this large crater, there is a huge canyon situated about two thirds of the way around its equator. Another strange thing to note about Tethys is the fact that the light colored regions found on its surface are heavily cratered, while the darker regions are lightly cratered.
Dione sports an impact crater roughly 37 miles in diameter named Padua Linea. The terrain on the surface of Dione is pot marked with many craters, and stress fractures that cover its entire surface. Orbiter images of Dione show what appears to be a swirled icy surface that covers one hemisphere, while a heavily bombarded surface dominates the other.
Another moon that resembles Iapetus, is the moon Mimas, which is only 200 miles in diameter, and has a crater a third as large as the moon itself. Mimas is believed to be responsible for the creation of the Cassini division.
There are five moons that are pretty close to Saturn, with diameters between 20 and 60 miles. These moons are either inside or very near the planets rings, and are called Sheppard moons, because they are responsible for herding the icy crystals and boulders that make up Saturn's rings into the formations we see today.
There are two tiny moons that orbit Saturn with Tethys, one in front and the other behind. Saturn's other moon Dione has a smaller companion known as Helene. Helene is an odd moon made up of mainly rock remnants, and looks like a great sponge. As far as I know Tethys and Dione are the only moons of Saturn that share their orbits with other moons within the E ring.
The largest moon of Saturn is Titan; it has a diameter of about 3,200 miles, and possesses an atmosphere half as thick as Earth's, comprised of massive amounts of methane and nitrogen. It is hard to observe Titan due to its atmosphere which contains massive amounts of gasses such as ethane and acetylene, that when combined cause the atmosphere to become very cloudy. Titan is the second largest moon in our solar system, when compared to Jupiter's moon Calisto.
According to spacecraft images sent back to Earth, we find Titan to be a very strange world indeed. When the Huygens probe landed on Titans surface, scientists were blown away by just how much this moon of Saturn resembled Earth. There were streams and rivers with deltas that dumped into what appeared as large bodies, of some type of liquid, which turns out to most likely be methane and ethane oceans. There were shorelines with canyons, and tributaries that ran vast distances inland.
When the probe first landed on the surface of Titan it began to sense moisture, so much in fact that the scientist believed that the source of a great amount of liquid must be just below the surface. So, the immediate question was how did all this moisture get here? The answer seems to fall in the discovery of a large hydrological system on Titan that reacts much like water does here on earth.
The surface of Titan is so cold that methane remains in liquid form, it evaporates, and it condenses, and then forms clouds which, cause rain, that in turn falls on the surface of Titan, which collects into run off that forms streams, pools, and large bodies of liquid methane. The outcome of all this action and reaction to chemical change produces organic compounds that mix and become suspended in the rain, which creates the haze that fills the atmosphere, and covers most of the surface of Titan.
These large bodies of liquid Methane gather into lakes, which are said to be at a temperature of -290 F. These lakes are filled by runoff from the many river channels that supply the various lakes with their organic compounds of methane and ethane. The orbiter Cassini's radar shows the surface of Titan to consist of three basic colors. The lighter shades are considered to be rough terrain, while the darker shades are thought to be smoother terrain. With the pitch black regions thought to be large bodies of liquid methane.
It has been reported that the northern regions of Titan are mostly populated by these large bodies of methane. The southern regions are dominated by lakes also, but these lakes for some reason are more elongated in shape. The age of these large lakes of methane is unknown. It is believed however that the polar regions of Titan retain a more humid climate, as compared to the equatorial regions. These lakes are believed to be the source of the methane rich atmosphere of Titan.
Climatic changes on Titan resemble that of Earth, in the respect that during the extended summer season, the Suns radiation heats the southern regions causing the liquid methane to evaporate and rise into the atmosphere, where it meets the colder polar air. This mixing of cold air and warm air generates massive storms that precipitate large amounts of condensation on the Polar Regions, which in turn refill the lakes. This is evident in the observation of storms rising in the southern pole and moving towards the colder pole to the north.
Phoebe is a captured moon, and not the creation of Saturn's accretion disc. Phoebe is 220 kilometer (135 miles) in diameter, and resides in an inclined retrograde orbit. This moon is more than likely a rouge asteroid remnant, of unknown composition.
Rhea is an odd moon its surface seems to indicate its age to be about that of the solar system (4.5 billon years), but orbital images seem to suggest a more youthful surface, due to the appearance of what seems to be a younger cleaner surface.
The other moons of Saturn are Atlas, Prometheus, Pandora, Janus, Calypso, Pan, Telesto, Hyperion, and the yet unnamed moon 1980 S 34. Ground based amateur telescopes of small apertures such as 8 inch and below, should be able to perceive Rhea, Phoebe, Dione, Tethys, Titan, and maybe even Enceladus if you're lucky. But, in 12inch and larger telescopes on good nights you can see all of the previously mentioned moons seen in the smaller telescopes plus Iapetus and Hyperion. In our 14inch Cassegrain from a dark site during times of a stable atmosphere we can see up to eleven moons, of the 31 known to exist.
THE PROBE CASINNI
As time carries on, the orbiter Cassini, will undoubtedly make a treasure trove of new discoveries, such as the one made in 2004, of two new moons, which could be the smallest objects orbiting Saturn so far. The moons are about 2 miles in diameter, and 2.5 miles in diameter respectively. The moons are approximately 120,000 miles and 131,000 miles from the center of Saturn, and are located between the orbits of Mimas and Enceladus. The names given them are S/2004S1, and S/2004S2.
Charnoz and the New Moons
The moons S/2004S1 and S/2004S2 were first discovered by a Dr. Sebastien Charnoz, who is a planetary dynamicist, working with Dr. Andre Brahic, of the University of Paris. In a statement released to the public, Dr. Charnoz said "Discovering these faint satellites was an exciting experience, especially the feeling of being the first person to see a new body of our solar system". "I had looked for such objects for weeks while at my office in Paris, but it was only once on my holiday, using my laptop, that my code eventually detected them. This tells me I should take more holidays".
Until now the smallest known moons in orbit around Saturn , were about 12 miles in diameter. Scientist for a long time have theorized that smaller moons should exist in orbit around Saturn, especially in the F ring. But what they did not expect was to find two moons this small orbiting between two major moons. The reason of coarse is the fact that moons this small should have been destroyed long ago by either collisions with other moons or cometary impacts, which were thought to frequent this region. This in itself speaks volumes on the theories laid out on the existence of objects in the Kuiper belt, and how they interact with the solar system
Another discovery of interest, and worth mentioning, was that of another group of rings around Saturn, discovered on September 20, 2006.
Here is a chart of the moons of Saturn.
NAME DIAMETER DISTANCE FROM SATURNS CENTER
Pan 12 m - 20 km 83,250m - 134,000 km
Atlas 19 m 30 km 85,300m - 137,248 km
Prometheus 140 m 225 km 86,600 m - 139,339 km
Pandora 120 m 193 km 88,100 m - 141,753 km
Epimetheus 55 m - 88 km 94,075 m - 151,397 km
Janus 60 m - 97 km 94,110 m - 151,447 km
Mimas 240 m 386 km 117,000 m - 188,192 km
Enceladus 310 m 500 km 149,230 m - 240,151 km
Tethys 650 m 140 km 184,250 m - 296,513 km
Calypso 11 m 18 km 184,970 m - 297,665 km
Telesto 11 m 18 km 184,970 m - 297,665 km
Rhea 950 m 1,529 km 327,940 m - 527,739 km
Helene 100 m 161 km 235,300 m - 378,598 km
Dione 700 m 1,126 km 235,500 m - 379,011 km
Titan 3,200 m 5,120 km 758,870 m - 1,221,227 km
Hyperion 180 m 290 km 933,360 m - 1,502,024 km
Iapetus 900 m 1,440 km 2,211,430 m - 3,558,786 km
Phoebe 120 m 193 km 6,540,000 m - 10,521,600 km
1981S10 11 m 18 km 204,965 m - 329,845 km
1981S11 11 m 18 km 220,000 m - 353,980 km
1981S7 11 m 18 km 235,960 m - 379,724 km
1981S8 11 m 18 km 235,960 m - 379,724 km
1980S34 11 m 18 km 204,965 m - 329,845 km
And Counting -
WHAT IS SATURN MADE OF
It has been said that if Saturn were hollow you could place 833 Earths inside it? That's strange when you think about it, because the estimated mass of Saturn is only that of 95 Earths. This means that Saturn must be comprised of very light materials that must be lighter than water. One cubic foot of Saturn, would weigh on average, about 44 pounds. Water weighs on the other hand 8 pounds per gallon. That means that a cubic foot of Saturn, would only weigh 70% that of a cubic foot of water.
According to researchers the orb of the planet is made up of many different types of gases, the most prominent being hydrogen and helium. The other materials involved form the clouds that make up the bands and other anomalies that we observe in our telescopes. The core of Saturn is probably a solid metal made up of highly compressed particles.
Unlike the cloud bands of Jupiter, the bands of Saturn change quite a lot so any chart made would be tentative to say the least. Even though Saturn is the second largest planet in our solar system, and has an equatorial diameter of 120,536 km placing it about 9.5 times the diameter of Earth. The polar radius however is around 10% less, causing Saturn to be the flattest of all the known planets in our solar system.
The orbital speed of Saturn tends to cause the cloud layers to coagulate then stretch out into ever changing bands. These bands are located at different latitudes across the planets surface. These bands although similar to Jupiter's are quite different in the respect that they are mostly devoid of ovals, festoons, and swirls which are indigenous to Jupiter. However - with equatorial wind speeds of well over 1,000 mph, it is hard to not have storms every now and then.
The atmospheric disturbances most noted by amateur astronomers, will occur at or near Saturn's equator. Most of the time storms are rare on Saturn's surface, occasionally they do spring up causing a huge up roar in the astronomical community, such as those that occurred in 1990, 1994, and 1996. During these exceptional sightings in 2002 and 2003 when the southern tropical zone seemed to come alive with storm activity, several bright spots were reported by amateur astronomers around the world.
Even though Saturn, is the second largest planet in our solar system, and lies at a distance of about 886,000,000 million miles from the Sun. It is approximately 75,000 miles across, that's about 9 times larger than the Earth, and when Saturn is compared to Jupiter in size it comes in at about a 1/3 of Jupiter's. Another interesting fact about Saturn is that while Earth revolves one complete revolution in 24 hours, it takes Saturn 11 hours to make one complete revolution.
Although Saturn is just as mysterious as it has always been, the many questions that have been answered by the handful of spacecraft that have been sent there, only present more questions than have been answered. However, one thing is for sure, had we not explored this great "Lord of the Rings", we as a people would surely have been the worst because of it.