Enceladus is based on Greek mythologyTitanNamed after Thetis.Cassini called the four he foundSaturnSatellites (EnceladusDione , LeahIapetus）ForSidera Lodoicea (Sidera Lodoicea)Louis XIV 。At the end of the 17th century, astronomers called themEnceladus、Enceladus、Enceladus、EnceladusAndRhea(including Titan).stayMimasAndEnceladusDiscovered in 1789, the number extends to Titan.In 1848, the last time that the order of numbering was changed, Hypelion pushed Iapetus to Iapetus.
astronomerJohn Friedrich William Herschel（William Herschel And the discoverer of Iapetus and Enceladus（Results of Astronomical Observations made at the Cape of Good Hope）It is suggested that these seven satellites shouldTitanThe proposal was formally adopted later.
Enceladus is made of ice, similar toRheaAndEnceladus。Its density is 0.97 g/cm3, indicating that Titan is almost composed of water ice.Titan's surface was heavily impacted by celestial bodies and has many ice cracks.It is one of the objects with the highest reflectivity in the solar system, with a reflectivity of 1.229.This high reflectivity is caused by Saturn's dim E-ring material, which also includes water ice ejected by Enceladus.
In the surface temperature map of Enceladus, NASA scientists found the Pac Man pattern.Two years ago, they also found this pattern in the image of Enceladus, which uses data from Cassini's synthetic infrared spectrometer.The temperature difference between scientists and surface materials may be different.In the image, areas with higher brightness may get more heat.[1]
Enceladus has two different landforms, one of which is composed of many holes, while the other is darkvolcanoConsisting of bands.Such a crater means that Enceladus once had internal geological activities, leading to the re emergence of ancient terrain on the surface.The exact cause of the formation of this dark volcanic zone is still unknown, but it may be fromGalileoPhotographedGanymedeAndGanymedeThe picture shows that their polar regions have bright ice caps, which is because the ice is deposited in volcanic craters inclined towards the poles.Enceladus may be in a similar situation, its polar region is also quite bright, and there are dark areas scattered in it.The western hemisphere of Titan is mainly a huge hole Odysseus, with a diameter of 400 kilometers, nearly the size of 2/5 of Titan.This hole is very flat, just like Ganymede's hole, without the moon andMercuryHigh ringed mountains and central uplift are common.This is probably due to the geological phenomenon caused by the impact of celestial bodies on the soft surface of Enceladus.
Enceladus (Fig. 1)
The second major feature of Enceladus is hugeIthaca Chasma Ithaca Chasma is 100km wide and 3-5 km deep.It extends 2000kilometreIt is about 3/4 of the circumference of Triton.The formation of Ithaca Canyon is believed to be due toEnceladusWhen the internal liquid solidifies, it causes volume expansion, and thus the surface of Enceladus cracks.The ocean beneath the earth's surface may lead to the formation of a 2:3Track resonance, which also leads to internaltidal heating And track eccentricity.The ocean then completely froze after Titan broke away from this resonant relationship.The potholes formed before the complete solidification of Titan are likely to be eliminated by subsequent geological activities.Astronomers also put forward another theory to explain the formation of Ithaca Canyon: the huge impact during the formation of the Odyssey pit caused the shock wave to spread all over Titan, causing the surface of the other side of Titan to break, forming Ithaca Canyon.The surface temperature of Enceladus is - 187 degrees Celsius.
[Orbital inclination] 1.12 ° (relative to Saturn's equator)
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Enceladus andTelestoandCalypsoUsing the same orbit, and respectively located at 60 degrees in front of and behind TitanLagrange pointUpper (L4 and L5).
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Enceladus (Fig. 2)
CassiniFly over at a distance of 1500 km on September 23, 2005Enceladus。Although Cassini will continue to study Enceladus during the extended mission, there are no plans for a closer overflight detection.[2]
Cassini's pictures of Titan
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In August 2018,NASA(NASA) released a high-definition image of Titan, which can clearly see the huge Odysseus crater.In the picture, Enceladus seems to be Saturn's only companion, bathed in "Saturn's glory".The picture was taken by Cassini at a distance of about 1.2 million kilometers from Saturn, showing that this medium-sized satellite was illuminated by the sunlight reflected from Saturn.[3]
