&sq=Qlik&lang=&file=File:Titan_in_true_color_by_Kevin_M._Gill.jpg) Titan, imaged by the Cassini orbiter, December 2011. A thick shroud of organic haze permanently obscures Titan's surface from viewing in visible light | |
| Discovery | |
|---|---|
| Discovered by | Christiaan Huygens |
| Discovery date | March 25, 1655 |
| Designations | |
Designation | Saturn VI |
| Pronunciation | /ˈtaɪtən/ [1] |
Named after | Τῑτάν Tītan |
| Adjectives | Titanian[2] or Titanean[3] (both /taɪˈteɪniən/)[4][5] |
| Orbital characteristics[6] | |
| Periapsis | 1186680 km |
| Apoapsis | 1257060 km |
| 1221870 km | |
| Eccentricity | 0.0288 |
| 15.945 d | |
Average orbital speed | 5.57 km/s (calculated) |
| Inclination | 0.34854° (to Saturn's equator) |
| Satellite of | Saturn |
| Physical characteristics | |
| 2574.73±0.09 km (0.404 Earths)[7] | |
| 8.3×107 km2 (0.163 Earths) | |
| Volume | 7.16×1010 km3 (0.066 Earths) |
| Mass | (1.3452±0.0002)×1023 kg (0.0225 Earths)[8] |
Mean density | 1.8798±0.0044 g/cm3[8] |
| 1.352 m/s2 (0.138 g) | |
| 0.3414±0.0005[9] (estimate) | |
| 2.641 km/s | |
| Synchronous | |
| Zero (to the orbital plane); 27° (to the sun) | |
| Albedo | 0.22 (geometric) [10] 0.265±0.03 (Bond)[11] |
| Temperature | 93.7 K (−179.5 °C)[12] |
| 8.2[13] to 9.0 | |
| Atmosphere | |
Surface pressure | 146.7 kPa (1.45 atm) |
| Composition by volume | Variable
Stratosphere: 95.0% N 2, 4.9% CH 4;[14] 97% N 2, 2.7±0.1% CH 4, 0.1–0.2% H 2[15] |
Titan is the largest moon of Saturn and the second-largest in the Solar System. It is the only moon known to have an atmosphere denser than the Earth's and is the only known object in space—other than Earth—on which there is clear evidence that stable bodies of liquid exist. Titan is one of seven gravitationally rounded moons of Saturn and the second-most distant among them. Frequently described as a planet-like moon, Titan is 50% larger in diameter than Earth's Moon and 80% more massive. It is the second-largest moon in the Solar System after Jupiter's Ganymede and is larger than Mercury; yet Titan is only 40% as massive as Mercury, because Mercury is mainly iron and rock while much of Titan is ice, which is less dense.
Discovered in 1655 by the Dutch astronomer Christiaan Huygens, Titan was the first known moon of Saturn and the sixth known planetary satellite (after Earth's moon and the four Galilean moons of Jupiter). Titan orbits Saturn at 20 Saturn radii or 1,200,000 km above Saturn's apparent surface. From Titan's surface, Saturn subtends an arc of 5.09 degrees, and if it were visible through the moon's thick atmosphere, it would appear 11.4 times larger in the sky, in diameter, than the Moon from Earth, which subtends 0.48° of arc.
Titan is primarily composed of ice and rocky material, with a rocky core surrounded by various layers of ice, including a crust of ice Ih and a subsurface layer of ammonia-rich liquid water. Much as with Venus before the Space Age, the dense opaque atmosphere prevented understanding of Titan's surface until the Cassini–Huygens mission in 2004 provided new information, including the discovery of liquid hydrocarbon lakes in Titan's polar regions and the discovery of its atmospheric super-rotation. The geologically young surface is generally smooth, with few impact craters, although mountains and several possible cryovolcanoes have been found.
The atmosphere of Titan is mainly nitrogen and methane; minor components lead to the formation of hydrocarbon clouds and heavy organonitrogen haze. Its climate—including wind and rain—creates surface features similar to those of Earth, such as dunes, rivers, lakes, seas (probably of liquid methane and ethane), and deltas, and is dominated by seasonal weather patterns as on Earth. With its liquids (both surface and subsurface) and robust nitrogen atmosphere, Titan's methane cycle nearly resembles Earth's water cycle, albeit at a much lower temperature of about 94 K (−179 °C; −290 °F). Due to these factors, Titan is called the most Earth-like celestial object in the Solar System.
- ^ "Titan". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
- ^ "Cassini Equinox Mission: Huygens Landed with a Splat". JPL. January 18, 2005. Archived from the original on June 20, 2010. Retrieved May 26, 2010.
- ^ Luz; et al. (2003). "Latitudinal transport by barotropic waves in Titan's stratosphere". Icarus. 166 (2): 343–358. doi:10.1016/j.icarus.2003.08.014.
- ^ "Titanian". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
- ^ "Titanian" is the written adjectival form of both Titan and Uranus's moon Titania. However, Uranus's moon has a Shakespearean pronunciation with a short "i" vowel and the "a" of spa: /tɪˈtɑːniən/, while either spelling for Titan is pronounced with those two vowels long: /taɪˈteɪniən/.
- ^ Unless otherwise specified: "JPL HORIZONS solar system data and ephemeris computation service". Solar System Dynamics. NASA, Jet Propulsion Laboratory. Archived from the original on October 7, 2012. Retrieved August 19, 2007.
- ^ Zebker, Howard A.; Stiles, Bryan; Hensley, Scott; Lorenz, Ralph; Kirk, Randolph L.; Lunine, Jonathan I. (May 15, 2009). "Size and Shape of Saturn's Moon Titan" (PDF). Science. 324 (5929): 921–923. Bibcode:2009Sci...324..921Z. doi:10.1126/science.1168905. PMID 19342551. S2CID 23911201. Archived from the original (PDF) on February 12, 2020.
- ^ a b Jacobson, R. A.; Antreasian, P. G.; Bordi, J. J.; Criddle, K. E.; Ionasescu, R.; Jones, J. B.; Mackenzie, R. A.; Meek, M. C.; Parcher, D.; Pelletier, F. J.; Owen, Jr., W. M.; Roth, D. C.; Roundhill, I. M.; Stauch, J. R. (December 2006). "The Gravity Field of the Saturnian System from Satellite Observations and Spacecraft Tracking Data". The Astronomical Journal. 132 (6): 2520–2526. Bibcode:2006AJ....132.2520J. doi:10.1086/508812.
- ^ Iess, L.; Rappaport, N. J.; Jacobson, R. A.; Racioppa, P.; Stevenson, D. J.; Tortora, P.; Armstrong, J. W.; Asmar, S. W. (March 12, 2010). "Gravity Field, Shape, and Moment of Inertia of Titan". Science. 327 (5971): 1367–1369. Bibcode:2010Sci...327.1367I. doi:10.1126/science.1182583. PMID 20223984. S2CID 44496742.
- ^ Williams, D. R. (February 22, 2011). "Saturnian Satellite Fact Sheet". NASA. Archived from the original on April 30, 2010. Retrieved April 22, 2015.
- ^ Li, Liming; et al. (December 2011). "The global energy balance of Titan" (PDF). Geophysical Research Letters. 38 (23). Bibcode:2011GeoRL..3823201L. doi:10.1029/2011GL050053. Retrieved August 20, 2023.
- ^ Mitri, G.; Showman, Adam P.; Lunine, Jonathan I.; Lorenz, Ralph D. (2007). "Hydrocarbon Lakes on Titan" (PDF). Icarus. 186 (2): 385–394. Bibcode:2007Icar..186..385M. doi:10.1016/j.icarus.2006.09.004. Archived (PDF) from the original on February 27, 2008.
- ^ Cite error: The named reference
arvalwas invoked but never defined (see the help page). - ^ Cite error: The named reference
Niemannwas invoked but never defined (see the help page). - ^ Coustenis & Taylor (2008), pp. 154–155.