The moon of Jupiter –
Thebe (XIV) – was previously temporarily designated as S/1979
J2. It was discovered in
photos sent from the →Voyager-1
spacecraft, which flew through the Jovian system on March 5, 1979. The one to draw
the right conclusions from these photos was S.P. Synnott and he is
currently known as the discoverer of that moon along with Metis.
The name of that moon is of mythological origin. Thebe was a nymph abducted by Zeus. The city of Thebes was named after
her.
The moon by this name is in a similar to circular prograde orbit (→eccentricity
e = 0.0176) with a →semimajor axis a = 221,900 km. At pericenter (closest to the planet) Thebe is separated from the Jupiter a distance of q = 217,995 km. At apocenter (furthest from the planet) this moon is separated from the Jupiter a distance of Q = 225,805 km.
Its mass is not big, ~1.4987×1018 kg that it is comparable to almost 204 mountains like Giewont
!
An in teresting feature of that moon is that the Voyager photos have shown its irregular shape to be marked by a few craters that turned out to be very large when compared to the satellite's overall size...
Its orbital period is only 0.7 day, which means that its mean celestial angular velocity in the sky is
533° (1.42 revolutions).
The main obstacle in discovery of that moon was its small angular distance from
Jupiter and also its low brightness only 16.0m
(exactly
10,000 times fainter than the faintest stars visible to the naked
eye). For comparison: Jupiter is about –2.7m,
so Thebe is shining fainter by about 18.7m.
It corresponds to a difference in brightness of almost 30.2 million times!
I have given some crucial data of Thebe below. Table one contains the basic
information. Whereas table two gives more detailed parametrs of its orbit (calculated using the following formulae).
Translated by Karol Pankowski
|
Thebe
|
|---|
| Mean distance from the planet [×103 km] |
221.9
|
| Mean distance from the planet [planetary R] |
3.1
|
| Orbital period [days] |
0.68
|
| Orbital eccentricity [e] |
0.0176
|
| Orbit inclination [degrees] |
1.1
|
| Mean diameter [km] |
98.6
|
| Main discoverer and year of the discovery |
S.P. Synnott 1980
|
| Visual magnitude [mag] |
16.0
|
| Mass [kg] |
~1.4987 × 1018
|
Orbital Parameters |
Pericenter
[q] |
Apocenter
[Q] |
| Distance from the planet [×103 km] |
218.0
|
225.8
|
| Distance from the planet [planetary R] |
3.0
|
3.2
|
| Angular size of the moon's orbit observed from the Earth* [degrees] |
0°01'11.51''
|
0°01'14.08''
|
|
| Angular diameter of the planet's disc as observed from the moon [degrees] |
38°17'53.42''
|
36°55'27.42''
|
| Brightness of the planet as observed from the moon** [mag] |
–20.0
|
–19.9
|
| Diameter of the moon's disc as observed from the planet's "surface" [degrees] |
0°02'18.82''
|
0°02'11.79''
|
| Brightness of the moon as observed from the planet's "surface"** [mag] |
–1.3
|
–1.2
|
|
Orbital velocity [km/sec] |
24.32
|
23.48
|
* This value is calculated for Jupiter at opposition (distance 628.8 million km = 4.2 AU)
** The given value of magnitude is not corrected for some decreasing factors (e.g. the changing phase of illumination)
|
See other related links:
Astronomy for every – Jupiter's moons
Monde
des Monats
– THEBE
Views
of the Solar System – THEBE
– Photo
Archives
Solar
System Exploration – THEBE
The
Nine Planets – THEBE
The Astronomy Workshop – Satellite Viewer
Planetary Satellite Mean Orbital Parameters
Natural Satellite Physical Parameters
 |
