The moon of Jupiter – Sinope (IX) – was discovered in
1914 by S. Nicholson. The discovery came 6 years after discovery Pasiphae.
It was the the first moon to be discovered by this astronomer. In the following years
S. Nicholson also discovered: Lysithea, Carme
and Ananke.
The name of that moon is of mythological origin. Sinope was daughter of the river god Asopus and Merope (one of the Pleiades
).
She was a woman said to have been unsuccessfully courted by... Zeus! However, she was eventually abducted by
Apollo...
The moon by this name
is in elliptical retrograde orbit
(→eccentricity
e = 0.2495) with a →semimajor axis a = 23,939,000 km. At pericenter (closest to the planet) Sinope is separated from the Jupiter a distance of q = 17,966,220 km. At apocenter (furthest from the planet) this moon is separated from the Jupiter a distance of Q = 29,911,781 km.
In future these parameters may vary due to a large orbital distance from Jupiter and the orbital motion being disturbed by the Sun and other factors. Perhaps it is a captured asteroid (with a diminutive mass: ~7.4933×1016 kg – it equals over 10 mountains like
Giewont!),
and in future will possibly return to heliocentric orbit.
The orbital period is almost 2.1 earthly
years, which means that the average speed of its celestial motion is
only 0°28'28'' per day. When this motion was detected and compared to the changes in Jupiter's position, this body was classified as a true planetary satellite (and not a distant celestial body with its position projected near the planet).
Other obstacle in detecting this moon earlier was its brightness of only 18.1m
(over 69 thousand times fainter than the faintest stars visible to naked eye). For comparison: Jupiter's brightness is about
–2.7m,
so Sinope is shining fainter by about 20.8m.
The corresponding difference in brightness is almost 209 million times!
I have given some crucial data of Sinope 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
|
Sinope
|
|---|
| Mean distance from the planet [×103 km] |
23,939.0
|
| Mean distance from the planet [planetary R] |
334.8
|
| Orbital period [days] |
758.90
|
| Orbital eccentricity [e] |
0.2495
|
| Orbit inclination [degrees] |
158.1
|
| Mean diameter [km] |
38.0
|
| Main discoverer and year of the discovery |
S. Nicholson 1914
|
| Visual magnitude [mag] |
18.1
|
| Mass [kg] |
~7.4933 × 1016
|
Orbital Parameters |
Pericenter
[q] |
Apocenter
[Q] |
| Distance from the planet [×103 km] |
17,966.2
|
29,911.8
|
| Distance from the planet [planetary R] |
251.3
|
418.4
|
| Angular size of the moon's orbit observed from the Earth* [degrees] |
1°38'14.62''
|
2°43'36.27''
|
|
| Angular diameter of the planet's disc as observed from the moon [degrees] |
0°27'21.56''
|
0°16'25.99''
|
| Brightness of the planet as observed from the moon** [mag] |
–10.4
|
–9.3
|
| Diameter of the moon's disc as observed from the planet's "surface" [degrees] |
0°00'00.44''
|
0°00'00.26''
|
| Brightness of the moon as observed from the planet's "surface"** [mag] |
10.3
|
11.4
|
|
Orbital velocity [km/sec] |
2.97
|
1.78
|
* 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
– PASIPHAEGRUPPE
Views
of the Solar System – SINOPE
Solar
System Exploration – SINOPE
The Nine Planets – SINOPE
The Astronomy Workshop – Satellite Viewer
Planetary Satellite Mean Orbital Parameters
Natural Satellite Physical Parameters
 |
