Tethys

Cassini view of Tethys showing the giant rift Ithaca Chasma.
Discovery
Discovered by	G. D. Cassini
Discovery date	March 21, 1684
Orbital characteristics
Semi-major axis	294,619 km
Eccentricity	0.0001[1][2]
Orbital period	1.887802 d[2]
Inclination	1.12° (to Saturn's equator)
Satellite of	Saturn
Physical characteristics
Dimensions	1080.8 × 1062.2 × 1055 km[3]
Mean radius	533.00 ± 0.70 km (0.083 Earths)[4]
Mass	6.17449 ± 0.00132×1020 kg[5] [4] (1.03×10-4 Earths)
Mean density	0.9735 ± 0.0038 g/cm³ [4]
Equatorial surface gravity	0.145 m/s2
Escape velocity	0.393 km/s
Rotation period	synchronous
Axial tilt	zero
Albedo	1.229 ± 0.005 (geometric)[6]
Temperature	86 K
Apparent magnitude	10.2 [7]
Adjectives	Tethyan

Tethys (pronounced /ˈtiːθɨs/ TEE-this, also /ˈtɛθɨs/ TETH-is, or as Greek Τηθύς) is a moon of Saturn that was discovered by Giovanni Domenico Cassini in 1684.^[8] For other uses, see Asteroid (disambiguation). ... 17 Thetis (thee-tÉ™s (key)) is a large Main belt asteroid. ... Cassini–Huygens is a joint NASA/ESA/ASI unmanned space mission intended to study Saturn and its moons. ... In geology, a rift is a place where the Earths lithosphere is expanding. ... Ithaca Chasma is a huge valley on Saturns moon Tethys. ... Giovanni Domenico (Jean-Dominique) Cassini Portrait Giovanni Domenico Cassini (June 8, 1625–September 14, 1712) was an Italian astronomer, engineer, and astrologer. ... is the 80th day of the year (81st in leap years) in the Gregorian calendar. ... Events France under Louis XIV makes Truce of Ratisbon separately with the Empire and Spain. ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ... A kilometer (Commonwealth spelling: kilometre), symbol: km is a unit of length in the metric system equal to 1,000 metres (from the Greek words χίλια (khilia) = thousand and μέτρο (metro) = count/measure). ... (This page refers to eccitricity in astrodynamics. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... Look up day in Wiktionary, the free dictionary. ... For the science fiction novella by William Shunn, see Inclination (novella). ... A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called the primary. ... Atmospheric characteristics Atmospheric pressure 140 kPa Hydrogen >93% Helium >5% Methane 0. ... For other uses, see Mass (disambiguation). ... Kg redirects here. ... For other uses, see Density (disambiguation). ... BIC pen cap, about 1 gram. ... A cubic centimetre (cm3) is an SI derived unit of volume, equal to the volume of a cube with side length of 1 centimetre. ... The surface gravity of a Killing horizon is the acceleration, as exerted at infinity, needed to keep an object at the horizon. ... Acceleration is the time rate of change of velocity and/or direction, and at any point on a velocity-time graph, it is given by the slope of the tangent to the curve at that point. ... Space Shuttle Atlantis launches on mission STS-71. ... In astronomy, a rotation period is the time an astronomical object takes to complete one revolution around its rotation axis relative to the background stars. ... Due to synchronous rotation of their moon, the inhabitants of the central body will never be able to see its green side. ... In astronomy, axial tilt is the inclination angle of a planets rotational axis in relation to a perpendicular to its orbital plane. ... For other uses, see Albedo (disambiguation). ... The geometric albedo of an astronomical body is the ratio of its total brightness at zero phase angle to that of an idealised fully reflecting, diffusively scattering (Lambertian) disk with the same cross-section. ... For other uses, see Temperature (disambiguation). ... For other uses, see Kelvin (disambiguation). ... The apparent magnitude (m) of a star, planet or other celestial body is a measure of its apparent brightness as seen by an observer on Earth. ... A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called the primary. ... Atmospheric characteristics Atmospheric pressure 140 kPa Hydrogen >93% Helium >5% Methane 0. ... Giovanni Domenico (Jean-Dominique) Cassini Portrait Giovanni Domenico Cassini (June 8, 1625–September 14, 1712) was an Italian astronomer, engineer, and astrologer. ... Events France under Louis XIV makes Truce of Ratisbon separately with the Empire and Spain. ...

Name

Tethys is named after the titan Tethys of Greek mythology. It is also designated Saturn III or S III Tethys. In Greek mythology, Tethys was a Titaness and sea goddess who was both sister and wife of Oceanus. ... The bust of Zeus found at Otricoli (Sala Rotonda, Museo Pio-Clementino, Vatican) 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 of their own cult and ritual practices. ...

Cassini named the four moons he discovered in 1671–1684 (Tethys, Dione, Rhea and Iapetus) Sidera Lodoicea ("the stars of Louis") to honour king Louis XIV. By the end of the seventeenth century, astronomers fell into the habit of referring to them and Titan as Saturn I through Saturn V (Tethys, Dione, Rhea, Titan, Iapetus). Once Mimas and Enceladus were discovered in 1789, the numbering scheme was extended to Saturn VII by bumping the older five moons up two slots. The discovery of Hyperion in 1848 changed the numbers one last time, bumping Iapetus up to Saturn VIII. Henceforth, the numbering scheme would remain fixed. Events May 9 - Thomas Blood, disguised as a clergyman, attempts to steal the Crown Jewels from the Tower of London. ... Events France under Louis XIV makes Truce of Ratisbon separately with the Empire and Spain. ... Atmosphere none Dione (dye-oe-nee, Greek Διώνη) is a moon of Saturn discovered by Giovanni Cassini in 1684. ... Atmosphere none Rhea (ree-a, Greek ‘Ρέα) is the second largest moon of Saturn and was discovered in 1672 by Giovanni Domenico Cassini. ... Iapetus (eye-ap-É™-tÉ™s, IPA , Greek Ιαπετός) is the third-largest moon of Saturn, discovered by Giovanni Domenico Cassini in 1671. ... Cassini Sidera Lodoicea (IPA ˈsɪdÉ™rÉ™ ËŒlÉ’dəʊˈɪʃə) is the name given by the astronomer Giovanni Domenico Cassini to the four moons of Saturn discovered by him in the years 1671, 1672, and 1684 and published in the Journal des sçavans in 1673 and 1686. ... Louis XIV redirects here. ... (16th century - 17th century - 18th century - more centuries) As a means of recording the passage of time, the 17th century was that century which lasted from 1601-1700. ... Titan (, from Ancient Greek Τῑτάν) or Saturn VI is the largest moon of Saturn and the only moon known to have a dense atmosphere. ... Mimas (mee-mÉ™s or mye-mÉ™s, IPA: , Greek Μίμᾱς, rarely Μίμανς) is a moon of Saturn that was discovered in 1789 by William Herschel. ... Apparent magnitude 11. ... Year 1789 (MDCCLXXXIX) was a common year starting on Thursday (link will display the full calendar) of the Gregorian calendar (or a common year starting on Monday of the 11-day slower Julian calendar). ... Hyperion (IPA: , Greek Ὑπερίων) is a moon of Saturn discovered by William Cranch Bond, George Phillips Bond and William Lassell in 1848. ... Year 1848 (MDCCCXLVIII) was a leap year starting on Saturday (link will display the full calendar) of the Gregorian Calendar (or a leap year starting on Monday of the 12-day slower Julian calendar). ...

The names of all seven satellites of Saturn then known come from John Herschel (son of William Herschel, discoverer of Mimas and Enceladus) in his 1847 publication Results of Astronomical Observations made at the Cape of Good Hope ^[9], wherein he suggested the names of the Titans, sisters and brothers of Kronos (the Greek analogue of Saturn), be used. John Herschel Sir John Frederick William Herschel (7 March 1792 – 11 May 1871) was an English mathematician and astronomer. ... For other persons named William Herschel, see William Herschel (disambiguation). ... 1847 was a common year starting on Friday (see link for calendar). ... This page is a candidate for speedy deletion, because: it is patent nonsense. ... Not to be confused with Chronos, the personification of time. ...

The correct adjectival form of the moon's name is Tethyan, although other forms are also used.

Physical characteristics

A composite image of Tethys' surface. (6MB)

Tethys is an icy body similar in nature to Dione and Rhea. The density of Tethys is 0.97 g/cm³, indicating that it is composed almost entirely of water-ice. The Tethyan surface is heavily cratered and contains numerous cracks caused by faults in the ice. Its surface is one of the most reflective (at visual wavelengths) in the solar system, with a visual albedo of 1.229.^[6] This very high albedo is the result of the sandblasting of particles from Saturn's E-ring, a faint ring composed of small, water-ice particles generated by Enceladus' south polar geysers. Atmosphere none Dione (dye-oe-nee, Greek Διώνη) is a moon of Saturn discovered by Giovanni Cassini in 1684. ... Atmosphere none Rhea (ree-a, Greek ‘Ρέα) is the second largest moon of Saturn and was discovered in 1672 by Giovanni Domenico Cassini. ... Tycho crater on Earths moon. ...

There are two different types of terrain found on Tethys, one composed of densely cratered regions and the other consisting of a dark colored and lightly cratered belt that extends across the moon. The light cratering of this second region indicates that Tethys was once internally active, causing parts of the older terrain to be resurfaced. The exact cause of the darkness of the belt is unknown but a possible interpretation comes from recent Galileo orbiter images of Jupiter's moons Ganymede and Callisto, both of which exhibit light polar caps that are made from bright ice deposits on pole-facing slopes of craters. From a distance the caps appear brighter due to the thousands of unresolved ice patches in small craters present there. The Tethyan surface may have been formed in a similar manner, consisting of hazy polar caps of unresolved bright ice patches with a darker zone in between. Galileo is prepared for mating with the IUS booster Galileo being deployed after being launched by the Space Shuttle Atlantis on the STS-34 mission Galileo was an unmanned spacecraft sent by NASA to study the planet Jupiter and its moons. ... This article is about the natural satellite of Jupiter. ... There is also an asteroid named 204 Kallisto. ... Resolving power is the ability of a microscope or telescope to measure the angular separation of images that are close together. ...

Odysseus is the huge, shallow crater on top, near the terminator

The western hemisphere of Tethys is dominated by a huge impact crater called Odysseus, whose 400 km diameter is nearly 2/5 of that of Tethys itself. The crater is now quite flat (or more precisely, it conforms to Tethys' spherical shape), like the craters on Callisto, without the high ring mountains and central peaks commonly seen on the Moon and Mercury. This is most likely due to the slumping of the weak Tethyan icy crust over geologic time. Odysseus is the huge, shallow crater on the right Odysseus is the largest crater on Saturns moon Tethys. ... Odysseus is the huge, shallow crater on the right Odysseus is the largest crater on Saturns moon Tethys. ... This article is about Earths moon. ... This article is about the planet. ...

The second major feature seen on Tethys is a huge valley called Ithaca Chasma, 100 km wide and 3 to 5 km deep. It runs 2000 km long, approximately 3/4 of the way around Tethys' circumference. It is thought that Ithaca Chasma formed as Tethys' internal liquid water solidified, causing the moon to expand and cracking the surface to accommodate the extra volume within. The subsurface ocean may have resulted from a 2:3 orbital resonance between Dione and Tethys early in the solar system's history that led to orbital eccentricity and tidal heating of Tethys' interior. The ocean would have frozen after the moons escaped from the resonance.^[10] Earlier craters that formed before Tethys solidified were probably all erased by geological activity before then. There is another theory about the formation of Ithaca Chasma: when the impact that caused the great crater Odysseus occurred, the shockwave traveled through Tethys and fractured the icy, brittle surface on the other side. The Tethyan surface temperature is -187°C. Ithaca Chasma is a huge valley on Saturns moon Tethys. ... In celestial mechanics, an orbital resonance occurs when two orbiting bodies exert a regular, periodic gravitational influence on each other. ... (This page refers to eccitricity in astrodynamics. ... It has been suggested that Tidal friction be merged into this article or section. ...

See also: List of geological features on Tethys

This is a list of named geological features on Tethys. ...

Trojan moons

The co-orbital moons Telesto and Calypso are located within Tethys' Lagrangian points L₄ and L₅, 60 degrees ahead and behind Tethys in its orbit respectively. Atmosphere none Telesto IPA: , Greek Τελεστώ) is a moon of Saturn. ... Atmosphere none Calypso (ka-lip-soe, Greek Καλυψώ) is a moon of Saturn. ... A contour plot of the effective potential (the Hills Surfaces) of a two-body system (the Sun and Earth here), showing the five Lagrange points. ...

Flybys

The Cassini orbiter performed a close targeted flyby of Tethys on September 23, 2005 at the distance 1500 km. Although Cassini will continue to observe Tethys at moderate distances during its extended mission, there are no plans for further close fly-bys. Cassini-Huygens is a joint NASA/ESA/ASI unmanned space mission intended to study Saturn and its moons. ... is the 266th day of the year (267th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ...

Tethys in fiction

Further information: Saturn's moons in fiction

Saturn and its moons Several of Saturns natural satellites of have figured prominently in works of science fiction. ...

References

2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance with the Gregorian calendar. ... is the 39th day of the year in the Gregorian calendar. ... Carolyn Porco Carolyn C. Porco is an American planetary scientist and the leader of the imaging science team on the Cassini mission[1],[2],[3] presently in orbit around Saturn. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... A digital object identifier (or DOI) is a standard for persistently identifying a piece of intellectual property on a digital network and associating it with related data, the metadata, in a structured extensible way. ... Richard French (June 20, 1792 - May 1, 1854) was a U.S. Representative from Kentucky. ... is the 40th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 271st day of the year (272nd in leap years) in the Gregorian calendar. ... William Lassell (June 18, 1799 – October 5, 1880) was a British astronomer, born in Bolton, Lancashire, England. ... Year 1848 (MDCCCXLVIII) was a leap year starting on Saturday (link will display the full calendar) of the Gregorian Calendar (or a leap year starting on Monday of the 12-day slower Julian calendar). ... is the 14th day of the year in the Gregorian calendar. ... 2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance with the Gregorian calendar. ... is the 73rd day of the year (74th in leap years) in the Gregorian calendar. ...

External links

• Tethys Profile by NASA's Solar System Exploration
• Rotating Tethys map (Voyager)
• The Planetary Society: Tethys

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