Saturn  

Saturn, as seen by Cassini
Orbital characteristics[1][2]
Epoch J2000
Aphelion	1,513,325,783 km 10. Cassini–Huygens is a joint NASA / ESA / ASI Robotic spacecraft mission currently studying the planet Saturn and its In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star In Astronomy, an epoch is a moment in time used as a reference for the Orbital elements of a Celestial body. In Astronomy, an epoch is a moment in time used as a reference for the Orbital elements of a Celestial body. In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from 11595804 AU
Perihelion	1,353,572,956 km 9. The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from 04807635 AU
Semi-major axis	1,433,449,370 km 9. In Geometry, the semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae 58201720 AU
Eccentricity	0. In Astrodynamics, under standard assumptions, any Orbit must be of Conic section shape 055723219
Orbital period	10,832. The orbital period is the time taken for a given object to make one complete Orbit about another object 327 days 29. A day (symbol d is a unit of Time equivalent to 24 Hours and the duration of a single Rotation of planet Earth with respect to the 657296 yr
Synodic period	378. In Astronomy, a Julian year (symbol a) is a unit of measurement of Time defined The orbital period is the time taken for a given object to make one complete Orbit about another object 09 days[3]
Average orbital speed	9. The orbital speed of a body generally a Planet, a Natural satellite, an artificial satellite, or a Multiple star, is the speed at which it 69 km/s[3]
Mean anomaly	320. In the study of orbital dynamics the mean anomaly of an orbiting body is the Angle the body would have traveled about the center of the orbit's Auxiliary circle 346750°
Inclination	2. Inclination in general is the Angle between a Reference plane and another plane or axis of direction 485240° 5. 51° to Sun's equator
Longitude of ascending node	113. The longitude of the ascending node (☊ or Ω is one of the Orbital elements used to specify the Orbit of an object in space 642811°
Argument of perihelion	336. The argument of periapsis (or argument of perifocus) ( ω) is the Orbital element describing the Angle of an Orbiting body's periapsis 013862°
Satellites	60 confirmed (up to 63 seen)
Physical characteristics
Equatorial radius	60,268 ± 4 km[4][5] 9. A natural satellite or moon is a Celestial body that Orbits a Planet or smaller body which is called the primary. Saturn has 60 confirmed moons. These include 22 regular satellites, which all have Prograde orbits that are not greatly inclined with respect The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the 4492 Earths
Polar radius	54,364 ± 10 km[4][5] 8. A geographical pole, or geographic pole, is either of two fixed points on the surface of a spinning body or Planet, at 90 degrees from the Equator, based 5521 Earths
Flattening	0. Ellipticity redirects here For the mathematical topic of ellipticity see Elliptic operator. 09796 ± 0. 00018
Surface area	4. Equation A spheroid centered at the origin and rotated about the z axis is defined by the implicit equation \left(\frac{x}{a}\right^2+\left(\frac{y}{a}\right^2+\left(\frac{z}{b}\right^2 27×1010 km²[6][5] 83. 703 Earths
Volume	8. The volume of any solid plasma vacuum or theoretical object is how much three- Dimensional space it occupies often quantified numerically 2713×1014 km³[3][5] 763. 59 Earths
Mass	5. Mass is a fundamental concept in Physics, roughly corresponding to the Intuitive idea of how much Matter there is in an object 6846×1026 kg[3] 95. 152 Earths
Mean density	0. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different 687 g/cm³[3][5] (less than water)
Equatorial surface gravity	8. Water is a common Chemical substance that is essential for the survival of all known forms of Life. The surface gravity, g, of an astronomical or other object is the Gravitational acceleration experienced at its surface 96 m/s²[3][5] 0. 914 g
Escape velocity	35. g-force (also G-force, g-load) is a measurement of an object's Acceleration expressed in g s In Physics, escape velocity is the speed where the Kinetic energy of an object is equal to the magnitude of its Gravitational potential energy 5 km/s[3][5]
Sidereal rotation period	0. The rotation period of an astronomical object is the time it takes to complete one revolution around its Axis of rotation relative to the background stars 439 – 0. 449 day[7] (10 h 32 – 47 min)
Equatorial rotation velocity	9. 87 km/s[5] 35,500 km/h
Axial tilt	26. In Astronomy, axial tilt is the Inclination angle of a planet's rotational axis in relation to its orbital plane. 73°[3]
North pole right ascension	2 h 42 min 21 s 40. Right ascension (abbrev RA; symbol α) is the Astronomical term for one of the two Coordinates of a point on the Celestial sphere 589°[4]
North pole declination	83. In Astronomy, declination (abbrev dec or δ) is one of the two coordinates of the Equatorial coordinate system, the other being either 537°[4]
Albedo	0. The albedo of an object is the extent to which it diffusely reflects light from the sun 342 (bond) 0. The Bond albedo is the fraction of power in the total electromagnetic radiation incident on an astronomical body that is scattered back out into space 47 (geom.)[3]
Surface temp.    1 bar level    0. The geometric albedo of an astronomical body is the ratio of its actual brightness at zero phase angle (i Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature 1 bar	min mean max 134 K[3] 84 K[3]
Apparent magnitude	+1. The kelvin (symbol K) is a unit increment of Temperature and is one of the seven SI base units The Kelvin scale is a thermodynamic The apparent magnitude ( m) of a celestial body is a measure of its Brightness as seen by an observer on Earth, normalized to the value 2 to -0. 24[8]
Angular diameter	14. The angular diameter of an object as seen from a given position is the "visual diameter" of the object measured as an angle 5" — 20. 1"[3] (excludes rings)
Adjectives	Saturnian
Atmosphere[3]
Scale height	59. A scale height is a term often used in scientific contexts for a distance over which a quantity decreases by a factor of e. 5 km
Composition	~96% Hydrogen (H2) ~3% Helium ~0. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Helium ( He) is a colorless odorless tasteless non-toxic Inert Monatomic Chemical 4% Methane ~0. Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. 01% Ammonia ~0. Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor 01% Hydrogen deuteride (HD) 0. Hydrogen deuteride is a bi-atomic substance of the two isotopes of Hydrogen: the majority isotope 1H protium and 2H Deuterium 0007% Ethane Ices: Ammonia water ammonium hydrosulfide(NH4SH)

Saturn ([ˈsætɚn] (help·info)^[9]) is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. ETHANE is a mnemonic indicating a protocol used by Emergency services to report situations which they may be faced with especially as it relates to major incidents where Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor Water is a common Chemical substance that is essential for the survival of all known forms of Life. Ammonium hydrosulfide is the Chemical compound with the formula (NH4SH A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is The Sun (Sol is the Star at the center of the Solar System. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. Along with the planets Jupiter, Uranus and Neptune it is classified as a gas giant (also known as a Jovian planet, after the planet Jupiter). Neptune ( English|AmE] ] is the eighth and farthest Planet from the Sun in the Solar System. A gas giant (sometimes also known as a Jovian planet after the planet Jupiter, or giant planet) is a large Planet that is not primarily It was named after the Roman god Saturnus, equated to the Greek Kronos (the Titan father of Zeus) and the Babylonian Ninurta. Saturn ( Latin: Saturnus) was a major Roman God of agriculture and harvest Greek mythology is the body of stories belonging to the ancient Greeks concerning their gods and Heroes the nature of the world and the origins and significance Cronus or Kronos, ( Ancient Greek Κρόνος Krónos) was the leader and the youngest of the first generation of Titans, divine descendants In Greek mythology, the Titans ( Greek: Tītā́n; plural Tītânes) were a race of powerful Deities that ruled during the legendary Zeus (zjuːs in Greek: nominative: Zeús /zdeús/ genitive: Diós; Modern Greek /'zefs/ in Greek mythology Ninurta ( Nin Ur: Lord of the Earth/Plough in Sumerian and Akkadian mythology was the god of Nippur, identified with Ningirsu Saturn's symbol represents the god's sickle (Unicode: ♄). A sickle is a hand-held Agricultural Tool with a curved Blade typically used for harvesting grain crop or cutting grass for Hay. In Computing, Unicode is an Industry standard allowing Computers to consistently represent and manipulate text expressed in most of the world's

The planet Saturn is composed of hydrogen, with small proportions of helium and trace elements. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Helium ( He) is a colorless odorless tasteless non-toxic Inert Monatomic Chemical ^[10] The interior consists of a small core of rock and ice, surrounded by a thick layer of metallic hydrogen and a gaseous outer layer. The planetary core consists of the innermost layer(s of a Planet. Metallic hydrogen results when Hydrogen is sufficiently Compressed and undergoes a phase change it is an example of Degenerate matter. The outer atmosphere is generally bland in appearance, although long-lived features can appear. An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " Wind speeds on Saturn can reach 1,800 km/h, significantly faster than those on Jupiter. Wind speed is the Speed of Wind, the movement of air or other gases in an atmosphere Saturn has a planetary magnetic field intermediate in strength between that of Earth and the more powerful field around Jupiter. In Physics, a magnetic field is a Vector field that permeates space and which can exert a magnetic force on moving Electric charges

Saturn has a prominent system of rings, consisting mostly of ice particles with a smaller amount of rocky debris and dust. Saturn has the most extensive Planetary ring system of any planet in the Solar System. Ice is a Solid phase, usually crystalline, of a Non-metalic substance that is liquid or gas at Room temperature, such as Ammonia Debris (ˈdeɪbriː/ /dɛˈbriː is a word used to describe the remains of something that has been otherwise destroyed Sixty known moons orbit the planet. Saturn has 60 confirmed moons. These include 22 regular satellites, which all have Prograde orbits that are not greatly inclined with respect Titan, Saturn's largest and the Solar System's second largest moon (after Jupiter's Ganymede), is larger than the planet Mercury and is the only moon in the Solar System to possess a significant atmosphere. TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as TemplateInfobox Planet.--> Ganymede (ˈgænɨmiːd, or as Greek ^[11]

Physical characteristics

A rough comparison of the sizes of Saturn and Earth.

Due to a combination of its lower density, rapid rotation, and fluid state, Saturn is an oblate spheroid; that is, it is flattened at the poles and bulges at the equator. An oblate Spheroid is a rotationally symmetric Ellipsoid having a polar axis shorter than the diameter of the equatorial circle whose plane Equation A spheroid centered at the origin and rotated about the z axis is defined by the implicit equation \left(\frac{x}{a}\right^2+\left(\frac{y}{a}\right^2+\left(\frac{z}{b}\right^2 A geographical pole, or geographic pole, is either of two fixed points on the surface of a spinning body or Planet, at 90 degrees from the Equator, based The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the Its equatorial and polar radii differ by almost 10% – 60268 km vs. 54364 km. ^[3] The other gas planets are also oblate, but to a lesser extent. Saturn is the only planet of the Solar System that is less dense than water. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different Although Saturn's core is considerably denser than water, the average specific density of the planet is 0. The planetary core consists of the innermost layer(s of a Planet. Relative density, sometimes called specific density, is the Ratio of the Density of a substance to the density of a given reference material 69 g/cm³ due to the gaseous atmosphere. Saturn is only 95 Earth masses,^[3] compared to Jupiter, which is 318 times the mass of the Earth^[12] but only about 20% larger than Saturn. ^[13]

Composition

The outer atmosphere of Saturn consists of about 93. 2% molecular hydrogen and 6. 7% helium. Trace amounts of ammonia, acetylene, ethane, phosphine, and methane have also been detected. Ammonia is a compound with the formula N[[hydrogen H3]] It is normally encountered as a Gas with a characteristic pungent Odor Acetylene ( IUPAC name ethyne), C2H2 is a Hydrocarbon belonging to the group of Alkynes It is the simplest of all alkynes ETHANE is a mnemonic indicating a protocol used by Emergency services to report situations which they may be faced with especially as it relates to major incidents where Phosphine is the common name for phosphorus hydride (PH3 also known by the IUPAC name phosphane and occasionally phosphamine. Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. ^[14] The upper clouds on Saturn are composed of ammonia crystals, while the lower level clouds appear to be composed of either ammonium hydrosulfide (NH₄SH) or water. Ammonium hydrosulfide is the Chemical compound with the formula (NH4SH ^[15] The atmosphere of Saturn is significantly deficient in helium relative to the abundance of the elements in the Sun.

The quantity of elements heavier than helium are not known precisely, but the proportions are assumed to match the primordial abundances from the formation of the Solar System. The total mass of these elements is estimated to be 19–31 times the mass of the Earth, with a significant fraction located in Saturn's core region. ^[16]

Internal structure

Saturn's temperature emissions: the prominent hot spot at the bottom of the image is at Saturn's south pole.

Though there is little direct information about Saturn's internal structure, it is thought that its interior is similar to that of Jupiter, having a small rocky core surrounded mostly by hydrogen and helium. The planetary core consists of the innermost layer(s of a Planet. Hydrogen (ˈhaɪdrədʒən is the Chemical element with Atomic number 1 Helium ( He) is a colorless odorless tasteless non-toxic Inert Monatomic Chemical The rocky core is similar in composition to the Earth, but denser. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 Above this, there is a thicker liquid metallic hydrogen layer, followed by a layer of liquid hydrogen and helium, and in the outermost 1,000 km a gaseous atmosphere. Metallic hydrogen results when Hydrogen is sufficiently Compressed and undergoes a phase change it is an example of Degenerate matter. ^[17] Traces of various ices are also present. The core region is estimated to be about 9–22 times the mass of the Earth. ^[18] Saturn has a very hot interior, reaching 11,700 °C at the core, and it radiates 2. 5 times more energy into space than it receives from the Sun. Most of the extra energy is generated by the Kelvin-Helmholtz mechanism (slow gravitational compression), but this alone may not be sufficient to explain Saturn's heat production. The Kelvin–Helmholtz mechanism is an astronomical process that occurs when the surface of a Star or a Planet cools An additional proposed mechanism by which Saturn may generate some of its heat is the "raining out" of droplets of helium deep in Saturn's interior, the droplets of helium releasing heat by friction as they fall down through the lighter hydrogen. Friction is the Force resisting the relative motion of two Surfaces in contact or a surface in contact with a fluid (e ^[19]

Cloud layers

Saturn's celestial body atmosphere exhibits a banded pattern similar to Jupiter's (the nomenclature is the same), but Saturn's bands are much fainter and are also much wider near the equator. An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " At the bottom, extending for 10 km and with a temperature of -23 °C, is a layer made up of water ice. After that comes a layer of ammonium hydrosulfide ice, which extends for another 50 km and is approximately at -93 °C. Eighty kilometers above that are ammonia ice clouds, where the temperatures are about -153 °C. Near the top, extending for some 200 km to 270 km above the clouds, come layers of visible cloud tops and a hydrogen and helium atmosphere. ^[20] Saturn's winds are among the Solar System's fastest. Voyager data indicate peak easterly winds of 500 m/s (1,800 km/h). See also Voyager 1 and Voyager 2. The Voyager program consists of a pair of unmanned scientific probes Voyager 1 and ^[10] Saturn's finer cloud patterns were not observed until the Voyager flybys. Since then, however, Earth-based telescopy has improved to the point where regular observations can be made. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation.

Saturn's usually bland atmosphere occasionally exhibits long-lived ovals and other features common on Jupiter. In 1990, the Hubble Space Telescope observed an enormous white cloud near Saturn's equator which was not present during the Voyager encounters, and, in 1994, another smaller storm was observed. The Hubble Space Telescope ( HST; also known colloquially as "the Hubble" or just "Hubble" is a space telescope that was carried into The 1990 storm was an example of a Great White Spot, a unique but short-lived phenomenon which occurs once every Saturnian year, or roughly every 30 Earth years, around the time of the northern hemisphere's summer solstice. The Great White Spot, also known as Great White Oval, on Saturn, named by analogy from Jupiter 's Great Red Spot, is a name given to periodic Solstices occur twice a year when the tilt of the Earth's axis is most oriented toward or away from the Sun, causing the Sun to reach its northernmost and southernmost extremes ^[21] Previous Great White Spots were observed in 1876, 1903, 1933, and 1960, with the 1933 storm being the most famous. If the periodicity is maintained, another storm will occur in about 2020. ^[22]

In recent images from the Cassini spacecraft, Saturn's northern hemisphere appears a bright blue, similar to Uranus, as can be seen in the image below. Cassini–Huygens is a joint NASA / ESA / ASI Robotic spacecraft mission currently studying the planet Saturn and its This blue color cannot currently be observed from Earth, because Saturn's rings are currently blocking its northern hemisphere. The color is most likely caused by Rayleigh scattering. Rayleigh scattering (named after Lord Rayleigh) is the elastic Scattering of Light or other electromagnetic radiation by particles much smaller

Saturn's northern hemisphere, as seen by Cassini. Note the planet's blue appearance through the ring.

North polar hexagonal cloud feature, discovered by Voyager 1 and confirmed in 2006 by Cassini. The Voyager 1 spacecraft is a 722-kilogram robotic Space probe of the outer Solar system and beyond launched September 5, Cassini–Huygens is a joint NASA / ESA / ASI Robotic spacecraft mission currently studying the planet Saturn and its ^[23]

Astronomers using infrared imaging have shown that Saturn has a warm polar vortex and that it is the only such feature known in the solar system. Infrared ( IR) radiation is Electromagnetic radiation whose Wavelength is longer than that of Visible light, but shorter than that of The polar vortex is a persistent large-scale Cyclone located near the Earth's Poles, in the middle and upper Troposphere and the Stratosphere This, they say, is the warmest spot on Saturn. Whereas temperatures on Saturn are normally -185 °C, temperatures on the vortex often reach as high as -122 °C. ^[24]

A persisting hexagonal wave pattern around the north polar vortex in the atmosphere at about 78°N was first noted in the Voyager images. Regular hexagon The internal Angles of a regular hexagon (one where all sides and all angles are equal are all 120 ° and the hexagon has 720 degrees ^[25][26] Unlike the north pole, HST imaging of the south polar region indicates the presence of a jet stream, but no strong polar vortex nor any hexagonal standing wave. ^[27] However, NASA reported in November 2006 that the Cassini spacecraft observed a 'hurricane-like' storm locked to the south pole that had a clearly defined eyewall. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program A tropical cyclone is a storm system characterized by a low pressure center and numerous Thunderstorms that produce strong winds and Flooding The eye is a region of mostly calm Weather found at the center of strong Tropical cyclones The eye of a Storm is a roughly circular area and typically 30–65 km ^[28] This observation is particularly notable because eyewall clouds had not previously been seen on any planet other than Earth (including a failure to observe an eyewall in the Great Red Spot of Jupiter by the Galileo spacecraft). Galileo was an Unmanned spacecraft sent by NASA to study the Planet Jupiter and its moons Named after the Astronomer ^[29]

The straight sides of the northern polar hexagon are each about 13,800 km long. The entire structure rotates with a period of 10h 39 m 24s, the same period as that of the planet's radio emissions, which is assumed to be equal to the period of rotation of Saturn's interior. The hexagonal feature does not shift in longitude like the other clouds in the visible atmosphere.

The pattern's origin is a matter of much speculation. Most astronomers seem to think some sort of standing-wave pattern in the atmosphere; but the hexagon might be a novel sort of aurora. More extreme speculation has Saturn's radio emissions emanating from the hexagon (something we can see and which has the right rotation period) rather than from the planet's interior (something we cannot see). ^[30] Polygon shapes have been replicated in spinning buckets of fluid in a laboratory. ^[31]

Magnetic field and magnetosphere

Saturn has an intrinsic magnetic field that has a simple, symmetric shape—a magnetic dipole. In physics there are two kinds of dipoles ( Hellènic: di(s- = two- and pòla = pivot hinge An electric dipole is a Its strength at the equator—0. 2 gauss (20 µT)—is approximately one twentieth than that of the field around Jupiter and slightly weaker than Earth's magnetic field. The gauss, abbreviated as G is the Cgs unit of Magnetic field B (which is also known as "magnetic flux density" and "magnetic The tesla (symbol T) is the SI derived unit of Magnetic field B (which is also known as "magnetic flux density" and "magnetic ^[32] As a result the cronian magnetosphere is much smaller than the jovian and extends slightly beyond the orbit of Titan. ^[33] Most probably, the magnetic field is generated similarly to that of Jupiter—by currents in the metallic-hydrogen layer, which is called a metallic-hydrogen dynamo. ^[33] Similarly to those of other planets, this magnetosphere is efficient at deflecting the solar wind particles from the Sun. The solar wind is a Stream of charged particles&mdasha plasma &mdashthat are ejected from the upper atmosphere of the Sun. The Sun (Sol is the Star at the center of the Solar System. The moon Titan orbits within the outer part of Saturn's magnetosphere and contributes plasma from the ionized particles in Titan's outer atmosphere. ^[32]

Orbit and rotation

Animation of hexagonal cloud feature.

The average distance between Saturn and the Sun is over 1,400,000,000 km (9 AU). The Sun (Sol is the Star at the center of the Solar System. The astronomical unit ( AU or au or au or sometimes ua) is a unit of Length based on the distance from the Earth to the With an average orbital speed of 9. 69 km/s,^[3] it takes Saturn 10,759 Earth days (or about 29½ years), to finish one revolution around the Sun. ^[3] The elliptical orbit of Saturn is inclined 2. 48° relative to the orbital plane of the Earth. ^[3] Because of an eccentricity of 0. In Astrodynamics, under standard assumptions, any Orbit must be of Conic section shape 056, the distance between Saturn and the Sun varies by approximately 155,000,000 km between perihelion and aphelion,^[3] which are the nearest and most distant points of the planet along its orbital path, respectively. In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from In Celestial mechanics, an apsis, plural apsides (ˈæpsɨdɪːz is the point of greatest or least distance of the Elliptical orbit of an object from

The visible features on Saturn rotate at different rates depending on latitude, and multiple rotation periods have been assigned to various regions (as in Jupiter's case): System I has a period of 10 h 14 min 00 s (844. 3°/d) and encompasses the Equatorial Zone, which extends from the northern edge of the South Equatorial Belt to the southern edge of the North Equatorial Belt. All other Saturnian latitudes have been assigned a rotation period of 10 h 39 min 24 s (810. 76°/d), which is System II. System III, based on radio emissions from the planet in the period of the Voyager flybys, has a period of 10 h 39 min 22. Radio astronomy is a subfield of Astronomy that studies celestial objects at radio frequencies. 4 s (810. 8°/d); because it is very close to System II, it has largely superseded it.

However, a precise value for the rotation period of the interior remains elusive. While approaching Saturn in 2004, the Cassini spacecraft found that the radio rotation period of Saturn had increased appreciably, to approximately 10 h 45 m 45 s (± 36 s). ^[34] The cause of the change is unknown—it was thought to be due to a movement of the radio source to a different latitude inside Saturn, with a different rotational period, rather than because of a change in Saturn's rotation.

Later, in March 2007, it was found that the rotation of the radio emissions did not trace the rotation of the planet, but rather is produced by convection of the plasma disc, which is dependent also on other factors besides the planet's rotation. It was reported that the variance in measured rotation periods may be caused by geyser activity on Saturn's moon Enceladus. TemplateInfobox Planet.--> This article is about the moon of The water vapor emitted into Saturn's orbit by this activity becomes charged and "weighs down" Saturn's magnetic field, slowing its rotation slightly relative to the rotation of the planet itself. At the time it was stated that there is no currently known method of determining the rotation rate of Saturn's core. ^[35][36][37]

The latest estimate of Saturn's rotation based on a compilation of various measurements from the Cassini, Voyager and Pioneer probes was reported in September 2007 is 10 hours, 32 minutes, 35 seconds. ^[38]

Planetary rings

The rings of Saturn (as imaged here by Cassini in 2007) are the most conspicuous in the Solar System. Saturn has the most extensive Planetary ring system of any planet in the Solar System. Cassini–Huygens is a joint NASA / ESA / ASI Robotic spacecraft mission currently studying the planet Saturn and its ^[17]

Main article: Rings of Saturn

Saturn is probably best known for its system of planetary rings, which makes it the most visually remarkable object in the solar system. Saturn has the most extensive Planetary ring system of any planet in the Solar System. A planetary ring is a ring of Cosmic dust and other small particles Orbiting around a Planet in a flat disc-shaped region ^[17]

History

The rings were first observed by Galileo Galilei in 1610 with his telescope, but he was unable to identify them as such. Galileo Galilei (15 February 1564 &ndash 8 January 1642 was a Tuscan ( Italian) Physicist, Mathematician, Astronomer, and Philosopher A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation. He wrote to the Duke of Tuscany that "The planet Saturn is not alone, but is composed of three, which almost touch one another and never move nor change with respect to one another. Cosimo II de' Medici Grand Duke of Tuscany (12 May 1590 &ndash 28 February 1621 ruled as Grand Duke of Tuscany from 1609 to 1621 They are arranged in a line parallel to the zodiac, and the middle one (Saturn itself) is about three times the size of the lateral ones [the edges of the rings]. Zodiac denotes an annual cycle of twelve stations along the Ecliptic, the apparent path of the sun across the heavens through the Constellations that divide the ecliptic " He also described Saturn as having "ears. " In 1612 the plane of the rings was oriented directly at the Earth and the rings appeared to vanish. Mystified, Galileo wondered, "Has Saturn swallowed his children?", referring to the myth of the god Saturn eating his own children to prevent them from overthrowing him. ^[39] Then, in 1613, they reappeared again, further confusing Galileo. ^[40]

In 1655, Christiaan Huygens became the first person to suggest that Saturn was surrounded by a ring. Christiaan Huygens (ˈhaɪgənz in English ˈhœyɣəns in Dutch) ( April 14, 1629 &ndash July 8, 1695) was a Dutch Using a telescope that was far superior to those available to Galileo, Huygens observed Saturn and wrote that "It [Saturn] is surrounded by a thin, flat, ring, nowhere touching, inclined to the ecliptic. "^[40]

In 1675, Giovanni Domenico Cassini determined that Saturn's ring was composed of multiple smaller rings with gaps between them; the largest of these gaps was later named the Cassini Division. Giovanni Domenico Cassini ( June 8, 1625 &ndash September 14, 1712) was an Italian Mathematician, Astronomer Saturn has the most extensive Planetary ring system of any planet in the Solar System. This division in itself is a 4,800 km wide region between the A Ring and B Ring. Saturn has the most extensive Planetary ring system of any planet in the Solar System. Saturn has the most extensive Planetary ring system of any planet in the Solar System. ^[41]

In 1859, James Clerk Maxwell demonstrated that the rings could not be solid or they would become unstable and break apart. James Clerk Maxwell (13 June 1831 &ndash 5 November 1879 was a Scottish mathematician and theoretical physicist. He proposed that the rings must be composed of numerous small particles, all independently orbiting Saturn. ^[42] Maxwell's theory was proven correct in 1895 through spectroscopic studies of the rings carried out by James Keeler of Lick Observatory. James Edward Keeler ( September 10 1857 – August 12 1900) was an American Astronomer. The Lick Observatory is an astronomical Observatory, owned and operated by the University of California.

Physical characteristics

Saturn's rings cut across an eerie scene that is ruled by Titan's luminous crescent and globe-encircling haze, broken by the small moon Enceladus, whose cryovolcanos are dimly visible at its south pole. TemplateInfobox Planet.--> This article is about the moon of A cryovolcano is literally an Icy Volcano. Cryovolcanoes form on Icy moons and possibly on other low- Temperature Astronomical objects North is up. Imaged by Cassini in 2006.

The rings can be viewed using a quite modest modern telescope or with good binoculars. Binocular telescopes, or binoculars (also known as field glasses are two identical or Mirror - symmetrical telescopes mounted side-by-side and They extend from 6,630 km to 120,700 km above Saturn's equator, average approximately 20 meters in thickness, and are composed of 93 percent water ice with a smattering of tholin impurities, and 7 percent amorphous carbon. Ice is a Solid phase, usually crystalline, of a Non-metalic substance that is liquid or gas at Room temperature, such as Ammonia Tholin (after the Greek word for muddy is a Heteropolymer formed by solar Ultraviolet irradiation of simple Organic compounds such as Methane Carbon (kɑɹbən is a Chemical element with the symbol C and its Atomic number is 6 ^[43] They range in size from specks of dust to the size of a small automobile. ^[44] There are two main theories regarding the origin of Saturn's rings. One theory, originally proposed by Édouard Roche in the 19th century, is that the rings were once a moon of Saturn whose orbit decayed until it came close enough to be ripped apart by tidal forces (see Roche limit). Édouard Albert Roche (1820-1883 was a French scientist who is best known for his work in the field of Celestial mechanics. The tidal force is a secondary effect of the Force of Gravity and is responsible for the Tides It arises because the gravitational acceleration experienced Determining the Roche limit The Roche limit depends on the rigidity of the satellite A variation of this theory is that the moon disintegrated after being struck by a large comet or asteroid. A comet is a small Solar System body that orbits the Sun and when close enough to the Sun exhibits a visible coma (atmosphere or a tail — Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but The second theory is that the rings were never part of a moon, but are instead left over from the original nebular material from which Saturn formed. A nebula (from Latin: "mist" pl nebulae or nebulæ, with ligature or nebulas) is an Interstellar cloud of This theory is not widely accepted today, since Saturn's rings are thought to be unstable over periods of millions of years and therefore of relatively recent origin.

While the largest gaps in the rings, such as the Cassini Division and Encke Gap, can be seen from Earth, both Voyager spacecraft discovered that the rings have an intricate structure of thousands of thin gaps and ringlets. Saturn has the most extensive Planetary ring system of any planet in the Solar System. This structure is thought to arise, in several different ways, from the gravitational pull of Saturn's many moons. Some gaps are cleared out by the passage of tiny moonlets such as Pan, many more of which may yet be discovered, and some ringlets seem to be maintained by the gravitational effects of small shepherd satellites such as Prometheus and Pandora. For the moon of Jupiter known by this name 1955-1975 see Carme (moon. A planetary ring is a ring of Cosmic dust and other small particles Orbiting around a Planet in a flat disc-shaped region TemplateInfobox Planet.--> Prometheus (proʊˈmiːθiəs,, or There is also an Asteroid called 55 Pandora. Other gaps arise from resonances between the orbital period of particles in the gap and that of a more massive moon further out; Mimas maintains the Cassini division in this manner. In Celestial mechanics, an orbital resonance occurs when two Orbiting bodies exert a regular periodic gravitational influence on each other usually due to their TemplateInfobox Planet. --> Mimas (ˈmaɪməs, or as Greek Still more structure in the rings consists of spiral waves raised by the moons' periodic gravitational perturbations.

Data from the Cassini space probe indicate that the rings of Saturn possess their own atmosphere, independent of that of the planet itself. The atmosphere is composed of molecular oxygen gas (O₂) produced when ultraviolet light from the Sun interacts with water ice in the rings. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Chemical reactions between water molecule fragments and further ultraviolet stimulation create and eject, among other things O₂. Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays According to models of this atmosphere, H₂ is also present. The O₂ and H₂ atmospheres are so sparse that if the entire atmosphere were somehow condensed onto the rings, it would be on the order of one atom thick. ^[45] The rings also have a similarly sparse OH (hydroxide) atmosphere. Like the O₂, this atmosphere is produced by the disintegration of water molecules, though in this case the disintegration is done by energetic ions that bombard water molecules ejected by Saturn's moon Enceladus. An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge TemplateInfobox Planet.--> This article is about the moon of This atmosphere, despite being extremely sparse, was detected from Earth by the Hubble Space Telescope. ^[46]

Saturn shows complex patterns in its brightness. ^[8] Most of the variability is due to the changing aspect of the rings,^[47][48] and this goes through two cycles every orbit. However, superimposed on this is variability due to the eccentricity of the planet's orbit that causes the planet to display brighter oppositions in the northern hemisphere than it does in the southern. ^[49]

In 1980, Voyager I made a fly-by of Saturn that showed the F-ring to be composed of three narrow rings that appeared to be braided in a complex structure; it is now known that the outer two rings consist of knobs, kinks and lumps that give the illusion of braiding, with the less bright third ring lying inside them.

Spokes of the rings

Spokes in the B ring, imaged by Voyager 2 in 1981

Until 1980, the structure of the rings of Saturn was explained exclusively as the action of gravitational forces. Voyager 2 is an unmanned Interplanetary Spacecraft launched on August 20, 1977. Gravitation is a natural Phenomenon by which objects with Mass attract one another The Voyager spacecraft found radial features in the B ring, called spokes, which could not be explained in this manner, as their persistence and rotation around the rings were not consistent with orbital mechanics. Saturn has the most extensive Planetary ring system of any planet in the Solar System. Orbital mechanics or astrodynamics is the application of Celestial mechanics to the practical problems concerning the motion of Rockets and other Spacecraft ^[50] The spokes appear dark in backscattered light, and bright in forward-scattered light. Backscatter is the reflection of Waves particles or signals back to the direction they came from In Telecommunication and Astronomy, forward scatter is the Deflection --by Diffraction, nonhomogeneous Refraction, or nonspecular It is assumed that they are microscopic dust particles that have levitated away from the ring plane and that they are connected to electromagnetic interactions, as they rotate almost synchronously with the magnetosphere of Saturn. Electromagnetism is the Physics of the Electromagnetic field: a field which exerts a Force on particles that possess the property of A magnetosphere' is a highly magnetized region around and possessed by an Astronomical object. However, the precise mechanism generating the spokes is still unknown. ^[51]

These are three images of the spokes imaged by Cassini in 2005. Cassini–Huygens is a joint NASA / ESA / ASI Robotic spacecraft mission currently studying the planet Saturn and its

Twenty-five years later, the spokes were observed again, this time by Cassini. They appear to be a seasonal phenomenon, disappearing in the Saturnian midwinter/midsummer and reappearing as Saturn comes closer to equinox. An equinox is the event of the Sun passing over the Earth's equator in its annual cycle The spokes were not visible when Cassini arrived at Saturn in early 2004. Some scientists speculated that the spokes would not be visible again until 2007, based on models attempting to describe spoke formation. Nevertheless, the Cassini imaging team kept looking for spokes in images of the rings, and the spokes reappeared in images taken on September 5, 2005. Events 1590 - Alexander Farnese 's army forces Henry IV of France to raise the siege of Paris. Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. ^[52]

Natural satellites

Main article: Moons of Saturn

Four of Saturn's moons: Dione, Titan, Prometheus (edge of rings), Telesto (top center)

Saturn has a large number of moons. Saturn has 60 confirmed moons. These include 22 regular satellites, which all have Prograde orbits that are not greatly inclined with respect TemplateInfobox Planet.--> Dione (daɪˈoʊni, or as in Greek TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as TemplateInfobox Planet.--> Prometheus (proʊˈmiːθiəs,, or TemplateInfobox Planet.--> Telesto (tɨˈlɛstoʊ, or as Greek A natural satellite or moon is a Celestial body that Orbits a Planet or smaller body which is called the primary. The precise figure is indeterminate, as the orbiting chunks of ice in Saturn's rings are all technically moons, and it is difficult to draw a distinction between a large ring particle and a tiny moon. As of 2007, 60 moons had been identified, plus 3 unconfirmed moons that could be large dust clumps in the rings. Of those, 52 had been given proper names. Many of the moons are very small: 34 are less than 10 km in diameter, and another 13 less than 50 km. ^[53] Only seven are massive enough to have collapsed into hydrostatic equilibrium under their own gravitation. Hydrostatic equilibrium occurs when compression due to Gravity is balanced by a Pressure gradient which creates a Pressure gradient force in the opposite These are compared with Earth's moon in the table below.

Titan, Saturn's largest moon, is the only moon in the Solar System to have a dense atmosphere. While most of the moons in the Saturnian system are small in size, Titan is, relatively speaking, gigantic. After the Sun, the eight planets and Jupiter's moon Ganymede, Titan is the most massive object in the Solar System. ^[11] Titan comprises more than 90 percent of the mass in orbit around Saturn, including the rings, and the other moons range from one hundredth to one hundred millionth its mass. ^[54]

Saturn's second largest moon Rhea may have a tenuous ring system of its own. TemplateInfobox Planet.--> Rhea (ˈriːə, or as in Greek The Saturnian moon Rhea may have a tenuous ring system consisting of three narrow relatively dense bands within a particulate disk ^[55]

Traditionally, most of Saturn's moons have been named after Titans of Greek mythology. In Greek mythology, the Titans ( Greek: Tītā́n; plural Tītânes) were a race of powerful Deities that ruled during the legendary This started because John Herschel—son of William Herschel, discoverer of Mimas and Enceladus—suggested doing so in his 1847 publication Results of Astronomical Observations made at the Cape of Good Hope,^[56] because they were the sisters and brothers of Cronos (the Greek Saturn). Sir John Frederick William Herschel 1st Baronet KH, FRS ( March 7, 1792 &ndash May 11, 1871)was an Sir Frederick William Herschel FRS KH ( 15 November 1738 – 25 August 1822) was a German -born British Cronus or Kronos, ( Ancient Greek Κρόνος Krónos) was the leader and the youngest of the first generation of Titans, divine descendants

For a timeline of discovery dates, see Timeline of discovery of Solar System planets and their natural satellites. TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as TemplateInfobox Planet.--> Iapetus (aɪˈæpɨtəs, or as in Greek Wikipedia talkFeatured lists for an explanation of this and other inclusion tags below-->This timeline of discovery of Solar System planets and their natural

History and exploration

Main article: Exploration of Saturn

A Hubble Space Telescope image, captured in October 1996, shows Saturn's rings from just past edge-on. The exploration of Saturn has been solely through unmanned spacecraft Credit: NASA/ESA. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program The European Space Agency ( ESA) established in 1975 is an intergovernmental organisation dedicated to the exploration of space, currently with 17 member

Ancient times and observation

See also: Planet#Etymology

Saturn has been known since prehistoric times. A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is ^[57] In ancient times, it was the most distant of the five known planets in the solar system (excluding Earth) and thus a major character in various mythologies. In ancient Roman mythology, the god Saturnus, from which the planet takes its name, was the god of the agricultural and harvest sector. Roman mythology, or more appropriately Latin mythology, refers to the mythological beliefs of the Italic people inhabiting the region of Latium and its Saturn ( Latin: Saturnus) was a major Roman God of agriculture and harvest ^[58] The Romans considered Saturnus the equivalent of the Greek god Kronos. Greek mythology is the body of stories belonging to the ancient Greeks concerning their gods and Heroes the nature of the world and the origins and significance ^[58] The Greeks had made the outermost planet sacred to Kronos,^[59] and the Romans followed suit.

In Hindu astrology, there are nine astrological objects, known as Navagrahas. Jyotiṣa ( Sanskrit jyotiṣa, from jyótis- "light heavenly body" also spelled Jyotish and Jyotisha in English Graha (from Sanskrit ग्रह gráha -- seizing laying hold of holding is a 'cosmic influencer' on the living beings of mother Bhumidevi ( Earth) Saturn, one of them, is known as "Sani" or "Shani," the Judge among all the planets, and by everyone accordingly to their own performed deeds bad or good. Shani ( Sanskrit Śani शनि is one of the Navagraha which are the nine primary celestial beings in Hindu astrology or ^[58] Ancient Chinese and Japanese culture designated the planet Saturn as the earth star (土星). The Chinese Zodiac is a 12 year cycle Each year of the 12 year cycle is named after one of the original 12 animals This was based on Five Elements which were traditionally used to classify natural elements. In traditional Chinese philosophy, natural phenomena can be classified into the Wu Xing ( or the Five Phases, usually translated as five elements, In ancient Hebrew, Saturn is called 'Shabbathai'. Its angel is Cassiel. Cassiel, ( Hebrew קפציאל Kafziel) is the Latin name of an Angel in post-biblical Judeo-Christian mythology particularly that of the Its intelligence, or beneficial spirit, is Agiel (layga), and its spirit (darker aspect) is Zazel (lzaz). Agiel (אגיאל The Intelligence (beneficial spirit of Saturn mentioned as a Spirit in such works as the Key of Solomon In Ottoman Turkish, Urdu and Malay, its name is 'Zuhal', derived from Arabic زحل. Urdu ( ur '''{{Nastaliq اردو}}''' trans Urdū, historically spelled Ordu) is a Central Indo-Aryan language Urdu is a standardised The Malay language ( ISO 639-1 code MS is an Austronesian language spoken by the Malay people and people of other ethnic groups who reside in the Arabic (ar الْعَرَبيّة (informally ar عَرَبيْ) in terms of the number of speakers is the largest living member of the Semitic language

Saturn's rings require at least a 75 mm diameter telescope to resolve and thus were not known to exist until Galileo first saw them in 1610. A telescope is an instrument designed for the observation of remote objects and the collection of Electromagnetic radiation. Galileo Galilei (15 February 1564 &ndash 8 January 1642 was a Tuscan ( Italian) Physicist, Mathematician, Astronomer, and Philosopher ^[60] He, though, thought of them as two moons on Saturn's sides. It was not until Christian Huygens used greater telescopic magnification that the rings were assumed to be rings. Christiaan Huygens (ˈhaɪgənz in English ˈhœyɣəns in Dutch) ( April 14, 1629 &ndash July 8, 1695) was a Dutch Huygens also discovered Saturn's moon Titan. Some time later, Jean-Dominique Cassini discovered four other moons: Iapetus, Rhea, Tethys, and Dione. Giovanni Domenico Cassini ( June 8, 1625 &ndash September 14, 1712) was an Italian Mathematician, Astronomer TemplateInfobox Planet.--> Iapetus (aɪˈæpɨtəs, or as in Greek TemplateInfobox Planet.--> Rhea (ˈriːə, or as in Greek TemplateInfobox Planet.--> Tethys (ˈtiːθɨs, /ˈtɛθɨs/, or TemplateInfobox Planet.--> Dione (daɪˈoʊni, or as in Greek In 1675, Cassini also discovered the gap now known as the Cassini Division. ^[61]

No further discoveries of significance were made until 1789 when William Herschel discovered two further moons, Mimas and Enceladus. Sir Frederick William Herschel FRS KH ( 15 November 1738 – 25 August 1822) was a German -born British TemplateInfobox Planet. --> Mimas (ˈmaɪməs, or as Greek TemplateInfobox Planet.--> This article is about the moon of The irregularly shaped satellite Hyperion, which has a resonance with Titan, was discovered in 1848 by a British team. TemplateInfobox Planet.--> Hyperion (haɪˈpɪəriən, or as in In Celestial mechanics, an orbital resonance occurs when two Orbiting bodies exert a regular periodic gravitational influence on each other usually due to their

In 1899 William Henry Pickering discovered Phoebe, a highly irregular satellite that does not rotate synchronously with Saturn as the larger moons do. William Henry Pickering ( February 15, 1858 &ndash January 17, 1938) was an American Astronomer, brother of Edward TemplateInfobox Planet.--> Phoebe (ˈfiːbi, or as in Greek In Astronomy, an irregular moon is a Natural satellite following a distant inclined, and often retrograde Orbit. Phoebe was the first such satellite found, and it takes more than a year to orbit Saturn in a retrograde orbit. Direct motion is the motion of a Planetary body in a direction similar to that of other bodies within its system and is sometimes called prograde motion. During the early twentieth century, research on Titan led to the confirmation in 1944 that it had a thick atmosphere - a feature unique among the solar system's moons.

Pioneer 11 flyby

Saturn was first visited by Pioneer 11 in September 1979. Pioneer 11 was the second mission (after its sister probe Pioneer 10) to investigate Jupiter and the Outer solar system and the first to explore the planet It flew within 20,000 km of the planet's cloud tops. Low resolution images were acquired of the planet and a few of its moons; the resolution of the images was not good enough to discern surface features. The spacecraft also studied the rings; among the discoveries were the thin F-ring and the fact that dark gaps in the rings are bright when viewed towards the Sun, or in other words, they are not empty of material. Pioneer 11 also measured the temperature of Titan. ^[62]

Voyager flybys

In November 1980, the Voyager 1 probe visited the Saturn system. The Voyager 1 spacecraft is a 722-kilogram robotic Space probe of the outer Solar system and beyond launched September 5, It sent back the first high-resolution images of the planet, rings, and satellites. Surface features of various moons were seen for the first time. Voyager 1 performed a close flyby of Titan, greatly increasing our knowledge of the atmosphere of the moon. However, it also proved that Titan's atmosphere is impenetrable in visible wavelengths; so, no surface details were seen. The flyby also changed the spacecraft's trajectory out from the plane of the solar system. ^[63]

Almost a year later, in August 1981, Voyager 2 continued the study of the Saturn system. Voyager 2 is an unmanned Interplanetary Spacecraft launched on August 20, 1977. More close-up images of Saturn's moons were acquired, as well as evidence of changes in the atmosphere and the rings. Unfortunately, during the flyby, the probe's turnable camera platform stuck for a couple of days, and some planned imaging was lost. Saturn's gravity was used to direct the spacecraft's trajectory towards Uranus. ^[63]

The probes discovered and confirmed several new satellites orbiting near or within the planet's rings. They also discovered the small Maxwell gap (a gap within the C Ring) and Keeler gap (a 42 km wide gap in the A Ring). Saturn has the most extensive Planetary ring system of any planet in the Solar System. Saturn has the most extensive Planetary ring system of any planet in the Solar System. Saturn has the most extensive Planetary ring system of any planet in the Solar System. Saturn has the most extensive Planetary ring system of any planet in the Solar System.

Cassini orbiter

Saturn eclipses the Sun, as seen from Cassini.

On July 1, 2004, the Cassini–Huygens spacecraft performed the SOI (Saturn Orbit Insertion) maneuver and entered into orbit around Saturn. "July 1st" redirects here For the Ayumi Hamasaki song see H (song. "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " Cassini–Huygens is a joint NASA / ESA / ASI Robotic spacecraft mission currently studying the planet Saturn and its Before the SOI, Cassini had already studied the system extensively. In June 2004, it had conducted a close flyby of Phoebe, sending back high-resolution images and data. TemplateInfobox Planet.--> Phoebe (ˈfiːbi, or as in Greek

Cassini's flyby of Saturn's largest moon, Titan, has captured radar images of large lakes and their coastlines with numerous islands and mountains. The orbiter completed two Titan flybys before releasing the Huygens probe on December 25, 2004. The Huygens probe, supplied by the European Space Agency (ESA and named after the Dutch 17th century astronomer Christiaan Huygens, is an atmospheric entry Events 274 - Roman Emperor Aurelian "MMIV" redirects here For the Modest Mouse album see " Baron von Bullshit Rides Again " Huygens descended onto the surface of Titan on January 14, 2005, sending a flood of data during the atmospheric descent and after the landing. Events 1129 - Formal approval of the Order of the Templar at the Council of Troyes. Year 2005 ( MMV) was a Common year starting on Saturday (link displays full calendar of the Gregorian calendar. During 2005, Cassini conducted multiple flybys of Titan and icy satellites. Cassini's last Titan flyby commenced on March 23, 2008. Events 1174 - Jocelin, Abbot of Melrose, is elected Bishop of Glasgow. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common

Since early 2005, scientists have been tracking lightning on Saturn, primarily found by Cassini. The power of the lightning is said to be approximately 1000 times than that of the lightning on Earth. In addition, scientists believe that this storm is the strongest of its kind ever seen. ^[64]

On March 10, 2006, NASA reported that, through images, the Cassini probe found evidence of liquid water reservoirs that erupt in geysers on Saturn's moon Enceladus. Events 241 BC - First Punic War: Battle of the Aegates Islands - The Romans sink the Carthaginian fleet bringing Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. A geyser is a Hot spring characterized by intermittent discharge of water ejected turbulently and accomplished by a vapour phase TemplateInfobox Planet.--> This article is about the moon of Images had also shown particles of water in its liquid state being emitted by icy jets and towering plumes. According to Dr. Andrew Ingersoll, California Institute of Technology, "Other moons in the solar system have liquid-water oceans covered by kilometers of icy crust. What's different here is that pockets of liquid water may be no more than tens of meters below the surface. "^[65]

On September 20, 2006, a Cassini probe photograph revealed a previously undiscovered planetary ring, outside the brighter main rings of Saturn and inside the G and E rings. Events 451 - The Battle of Chalons takes place in North Eastern France. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Apparently, the source of this ring is the result of the crashing of a meteoroid off two of the moons of Saturn. ^[66]

In July 2006, Cassini saw the first proof of hydrocarbon lakes near Titan's north pole, which was confirmed in January 2007. In March 2007, additional images near Titan's north pole discovered hydrocarbon "seas", the largest of which is almost the size of the Caspian Sea. The Caspian Sea is the largest enclosed body of water on Earth by area variously classed as the world's largest lake or a full-fledged Sea. ^[67]

In October 2006, the probe detected a 5,000 km diameter hurricane with an eyewall at Saturn's South Pole. ^[68]

As of 2006, the probe has discovered and confirmed 4 new satellites. Its primary mission will end in 2008 when the spacecraft will be expected to have completed 74 orbits around the planet. The probe, however, is expected to have at least one mission extension.

Best viewing

Saturn Oppositions: 2001–2029

Saturn is the most distant of the five planets easily visible to the naked eye, the other four being Mercury, Venus, Mars, and Jupiter (Uranus and occasionally 4 Vesta are visible to the naked eye in very dark skies), and was the last planet known to early astronomers until Uranus was discovered in 1781. The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University TemplateInfobox Planet. --> 4 Vesta (ˈvɛstə Vesta is the second most massive object in the Asteroid belt Saturn appears to the naked eye in the night sky as a bright, yellowish point of light whose magnitude is usually between +1 and 0 and takes approximately 29½ years to make a complete circuit of the ecliptic against the background constellations of the zodiac. The ecliptic is the apparent path that the Sun traces out in the sky during the year Zodiac denotes an annual cycle of twelve stations along the Ecliptic, the apparent path of the sun across the heavens through the Constellations that divide the ecliptic Most people will require optical aid (large binoculars or a telescope) magnifying at least 20X to clearly resolve Saturn's rings. ^[17]

While it is a rewarding target for observation for most of the time it is visible in the sky, Saturn and its rings are best seen when the planet is at or near opposition (the configuration of a planet when it is at an elongation of 180° and thus appears opposite the Sun in the sky). Opposition is a term used in Positional astronomy and Astrology to indicate when one celestial body is on the opposite side of the sky when viewed from (For other uses of elongation see Elongation) Elongation is an Astronomical term that refers to the angle between the Sun and a planet During the opposition of December 17, 2002, Saturn appeared at its brightest due to a favorable orientation of its rings relative to the Earth. Events 546 - Gothic War (535–554: The Ostrogoths of King Totila See also 2002 (disambiguation Year 2002 ( MMII) was a Common year starting on Tuesday of the Gregorian calendar. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 ^[48]

See also

• Dragon Storm (astronomy)
• Saturn in astrology
• Saturn in fiction

References

• Lovett, L. ; Horvath, J. ; Cuzzi, J. (2006). Saturn: A New View. New York: Harry N. Abrams, Inc. . ISBN 0810930900.  
• Karttunen, H. ; Kröger, P. ; et al. (2007). Fundamental Astronomy. New York: Springer, 5th edition. ISBN 3540341439.  

External links

• Introduction to Saturn by NASA's Solar System Exploration
• Saturn Fact Sheet, by NASA
• Cassini-Huygens mission to Saturn, by NASA
• Research News about Saturn
• General information about Saturn
• Studies on the Rings of Saturn
• Astronomy Cast: Saturn