ثالاسا (قمر)

**Thalassa**
	; Naiad or Thalassa as seen by Voyager 2; (smearing has caused excessive elongation)
Discovery
Discovered by	Richard J. Terrile and Voyager Imaging Team
Discovered in	September 1989
Orbital characteristics
	Epoch 18 August 1989
Semi-major axis	50 075 ± 1 km
Eccentricity	0.0002 ± 0.0002
Orbital period	0.31148444 ± 0.00000006 d
Inclination	0.21 ± 0.02° (to Neptune equator); 0.21° (to local Laplace plane);
Is a satellite of	Neptune
Physical characteristics
Dimensions	108×100×52 km
Mean radius	41 ± 3 km
Mass	~3.5×1017 kg ; (based on assumed density)
Mean density	~1.2 g/cm3 (estimate)
Rotation period	assumed synchronous
Axial tilt	~zero presumably
Albedo (geometric)	0.09
Surface temp.	~51 K mean (estimate)
Atmosphere	none

ثالاسا Thalassa تابع طبيعي أحد أقمار الكوكب نبتون اكتشفته المركبة الفضائية فوياجير الثانية سنة 1989م أثناء لقاءها بالكوكب الأم نبتون ضمن برنامج فوياجير الفضائي ,ولم يكن يعرف من قبل .

A simulated view of Thalassa orbiting Neptune.

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الخصائص الفيزيائية

هو قمر صغير (قمير) يبلغ قطره نحو 80 كيلو متر ومعدل مسافته عن كوكبه الأم نحو 50,000 كيلو متر .

أنظر أيضا

نبتون

المصادر

مؤمن, عبد الأمير (2006). قاموس دار العلم الفلكي. بيروت، لبنان: دار العلم للملايين. {{cite book}}: Cite has empty unknown parameter: |طبعة أولى coauthors= (help)

^ Planet Neptune Data http://www.princeton.edu/~willman/planetary_systems/Sol/Neptune/
^ R.A. Jacobson and W.M. Owen Jr. (2004). "The orbits of the inner Neptunian satellites from Voyager, Earthbased, and Hubble Space Telescope observations". Astronomical Journal. 128: 1412. doi:10.1086/423037.
^ ^أ ^ب E. Karkoschka (2003). "Sizes, shapes, and albedos of the inner satellites of Neptune". Icarus. 162: 400. doi:10.1016/S0019-1035(03)00002-2.
^ ^أ ^ب Williams, Dr. David R. (2008-01-22). "Neptunian Satellite Fact Sheet". NASA (National Space Science Data Center). Retrieved 2008-12-13.
^ "Planetary Satellite Physical Parameters". JPL (Solar System Dynamics). 2008-10-24. Retrieved 2008-12-13.

وصلات خارجية

قالب:Moons of Neptune

[1] Planet Neptune Data http://www.princeton.edu/~willman/planetary_systems/Sol/Neptune/

[jacobson04-2] R.A. Jacobson and W.M. Owen Jr. (2004). "The orbits of the inner Neptunian satellites from Voyager, Earthbased, and Hubble Space Telescope observations". Astronomical Journal. 128: 1412. doi:10.1086/423037.

[Karkoschka-3] أ ^ب E. Karkoschka (2003). "Sizes, shapes, and albedos of the inner satellites of Neptune". Icarus. 162: 400. doi:10.1016/S0019-1035(03)00002-2.

[nssdc-4] أ ^ب Williams, Dr. David R. (2008-01-22). "Neptunian Satellite Fact Sheet". NASA (National Space Science Data Center). Retrieved 2008-12-13.

[jplssd-5] "Planetary Satellite Physical Parameters". JPL (Solar System Dynamics). 2008-10-24. Retrieved 2008-12-13.

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[2]

[3]

[4]

[5]

Discovery
Naiad or Thalassa as seen by Voyager 2 (smearing has caused excessive elongation)
Discovered by	Richard J. Terrile^[1] and Voyager Imaging Team
Discovered in	September 1989
Orbital characteristics^[2]
Epoch 18 August 1989
Semi-major axis	50 075 ± 1 km
Eccentricity	0.0002 ± 0.0002
Orbital period	0.31148444 ± 0.00000006 d
Inclination	0.21 ± 0.02° (to Neptune equator) 0.21° (to local Laplace plane)
Is a satellite of	Neptune
Physical characteristics
Dimensions	108×100×52 km^[3]^[4]
Mean radius	41 ± 3 km^[5]
Mass	~3.5×10¹⁷ kg (based on assumed density)
Mean density	~1.2 g/cm³ (estimate)
Rotation period	assumed synchronous
Axial tilt	~zero presumably
Albedo (geometric)	0.09^[3]^[4]
Surface temp.	~51 K mean (estimate)
Atmosphere	none