本帖最後由 WCYue 於 2023-7-18 11:05 編輯
2024年土星衛星現象
Eclipses, occultations and transits - with the Planet
As moons orbit around a planet, they undergo eclipses, occultations and transits with the body of the planet. For Saturn, Uranus and Neptune, these events only occur when the equatorial plane of the planet is near to edge-on. This option is for computing these events.
The moons included in the predictions, and the frequency of events, are as follows:
Saturn. Predictions are generated for satellites 3 to 6, and 8 (Tethys, Dione, Rhea, Titan, and Iapetus). Events involving Mimas and Enceladus are not included as they are unlikley to be observable, and are large in number. Events occur for a period of about 4 years every 14 years. In the first half of the 21st century, events occur between Sep 2007 & Oct 2011, Feb 2023 & Apr 2027, Nov 2036 & Aug 2041, and May 2052 to Mar 2057.
Events involving Iapetus occur about 12 months before the other satellites (and the time periods given above) because of the large inclination of the orbit. Because of the large inclination, additional events involving the transit of Iapetus, and of its shadow, on the rings of Saturn are included. The visibility of events against the rings on the 'far side' of Saturn involve two extra considerations that are unique to these events. They are whether, at an event time: the shadow of Iapetus on the rings is occulted by the disk of Saturn, and whether Iapetus is projected against the shadow of Saturn on the rings. These situations involve significant complexities in their determination, and are vary rare. They are not considered in the prediction; as a result it is possible for some Iapetus transit events to not be visible when they occur against the far side of the rings.
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發表於 2023-7-18 10:55:22