| 词条 | Atlas (moon) | |||||
| 释义 |
| name = Atlas | alt_names = Saturn XV | adjectives = Atlantean | pronounced = {{IPAc-en|ˈ|æ|t|l|ə|s}} | image = Atlas 2017-04-12 raw preview.jpg | caption = Photo taken by Cassini on 12 April 2017 | discoverer = Terrile, Voyager 1 | discovered = October, 1980 | orbit_ref = {{sfn|Spitale Jacobson et al.|2006}} | epoch = December 31, 2003 (JD {{val|2453005.5}}) | mean_orbit_radius = {{val|137670|10|u=km}} | eccentricity = {{val|0.0012}} | period = {{val|0.6016947883|u=d}} | inclination = {{val|0.003|0.004|u=°}} | satellite_of = Saturn | dimensions = 40.8 × 35.4 × 18.8 km {{sfn|Thomas|2010}} | mean_radius = {{val|15.1|0.9|u=km|s= }}{{sfn|Thomas|2010}} | volume = {{val|p=≈ |14400|u=km3}} | mass = {{val|6.60|0.45|e=15|u=kg}}{{sfn|Thomas|2010}} | density = {{val|0.46|0.11|u=g/cm3}}{{sfn|Thomas|2010}} | surface_grav = 0.0002–0.0020 m/s2 {{sfn|Thomas|2010}} | escape_velocity = {{val|p=≈ |0.0062|u=km/s}} | rotation = synchronous | axial_tilt = zero | albedo = 0.4 | single_temperature = ≈ 81 K }} Atlas is an inner satellite of Saturn. Atlas was discovered by Richard Terrile in 1980 (some time before November 12) from Voyager photos and was designated {{nowrap|S/1980 S 28}}.{{sfn|IAUC 3539}} In 1983 it was officially named after Atlas of Greek mythology, because it "holds the rings on its shoulders" like the Titan Atlas held the sky up above the Earth.{{sfn|IAUC 3872}} It is also designated {{nowrap|Saturn XV}}. Atlas is the closest satellite to the sharp outer edge of the A ring, and was long thought to be a shepherd satellite for this ring. However, now it is known that the outer edge of the ring is instead maintained by a 7:6 orbital resonance with the larger but more distant moons Janus and Epimetheus.{{sfn|Lakdawalla|2007}} In 2004 a faint, thin ring, temporarily designated {{nowrap|R/2004 S 1}}, was discovered in the Atlantean orbit.{{sfn|IAUC 8401}} High-resolution images taken in June 2005 by Cassini revealed Atlas to have a roughly spherical centre surrounded by a large, smooth equatorial ridge. The most likely explanation for this unusual and prominent structure is that ring material swept up by the moon accumulates on the moon, with a strong preference for the equator due to the ring's thinness. In fact, the size of the equatorial ridge is comparable with the expected Roche lobe of the moon. This would mean that for any additional particles impacting the equator, the centrifugal force will nearly overcome Atlas's tiny gravity, and they will probably be lost.{{sfn|Lakdawalla|2007}} Atlas is significantly perturbed by Prometheus and to a lesser degree by Pandora, leading to excursions in longitude of up to 600 km (~0.25°) away from the precessing Keplerian orbit with a rough period of about 3 years. Because the orbits of Prometheus and Pandora are chaotic, it is suspected that Atlas's may be as well.{{sfn|Spitale Jacobson et al.|2006}} GalleryReferencesCitationsSources
| last = Green | first = Daniel W. E. | title = S/2004 S 3, S/2004 S 4, and R/2004 S 1 | date = September 9, 2004 | journal = IAU Circular | volume = 8401 | url = http://www.cbat.eps.harvard.edu/iauc/08400/08401.html | accessdate = 2011-12-30 | ref = {{sfnRef|IAUC 8401}}
| last = Lakdawalla | first = Emily | date = June 13, 2007 | title = Funny little Atlas | work = The Planetary Society weblog | url = http://www.planetary.org/blog/article/00001003/ | accessdate = 2011-12-30 | ref = harv
|last=Marsden |first=Brian G. |title=1980 S 28 |date=November 13, 1980 |format=discovery |journal=IAU Circular |volume=3539 |url=http://www.cbat.eps.harvard.edu/iauc/03500/03539.html |accessdate=2011-12-30 |ref={{sfnRef|IAUC 3539}} |deadurl=yes |archiveurl=https://web.archive.org/web/20111213152218/http://www.cbat.eps.harvard.edu/iauc/03500/03539.html |archivedate=2011-12-13 |df= }}
| last = Marsden | first = Brian G. | title = Satellites of Jupiter and Saturn | date = September 30, 1983 | format = naming the moon | journal = IAU Circular | volume = 3872 | url = http://www.cbat.eps.harvard.edu/iauc/03800/03872.html | accessdate = 2011-12-30 | ref = {{sfnRef|IAUC 3872}}
External links{{Commons category|Atlas (moon)}}{{Spoken Wikipedia|Atlas (moon).ogg|2010-01-13}}
2 : Moons of Saturn|Astronomical objects discovered in 1980 |
|||||
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。