Amalthea is the third closest known to JupiterNatural satellite, an irregular shaped satellite, used by Edward Emerson Barnard on September 9, 1892Lick Observatory One is 91cm in diameterRefracting telescopeIt is the last satellite discovered by naked eye.The International Astronomical Association raised a goat with milk in Greek mythologyZeusThe fairy's name is Amar Sai.
Ganymede, the third closest natural satellite known to Jupiter, was used by Edward Emerson Barnard on September 9, 1892Lick Observatory 36 inches (91 cm)Refracting telescopeIt was the last satellite discovered by naked eye observation (later discoveries were generally made by using photos or other methods), and it was also the first Jupiter satellite discovered after Galileo Galilei discovered four Jupiter satellites in 1610.In March 1979, Voyager 1Space probeIt is found that Ganymede is light gray, with a reddish area about 130 km long and 200~220 km wide.Ganymede and three other Jupiter's inner moons are in the same family.Ganymede is the largest of them.
The International Astronomical Association named it Amalthea.In Greek mythology, Amarsse was a fairy who raised Zeus (Jupiter) with the milk of a goat.Please note that in addition to Ganymede, Ares (Asteroid 113) is also known as Amalthea[1]。
Ganymede radiates more heat than it receives sunlight, which may be due to its internalmagnetic fieldCaused by the induced current in.Ganymede and three other Jupiter's inner moons are in the same family.Ganymede is the largest of them.Ganymede's revolution and rotation cycle are the same.Like Io, most of Jupiter's moons, Ganymede rotates synchronously, and its long axis points directly at Jupiter.[2]
Ganymede has a very small density - roughly equal to the density of ice, although there is not much ice in its composition.Therefore, scientists believe that Ganymede is not a whole structure, but a large number of space pebbles. These pebbles are gathered together by gravity.In some cases, the adjacent pebbles will only slightly collide with each other, while the vacuum is still between them.It is very likely that Ganymede was originally a whole structure, but it was later smashed into a pile of pebbles due to the impact with an asteroid.[3]
Appearance
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Ganymede (mimic diagram)
Ganymede has an irregular shape. Its three axes are 250 × 146 × 128 kilometers long, and its long axis points to Jupiter.It hasCraterCompared with its size, the largest Pan has a diameter of 100 kilometers and a depth of 8 kilometers;Another crater（Gaia）It is 80km in diameter and twice as deep as Pan.There are also two mountains on Ganymede, which are 20 kilometers higher than other parts.Ganymede is the reddest celestial body in the solar system. It is even redder than Mars.Its red color comes fromIouppervolcanoSulfur emitted.There are also green spots on the main slope of Ganymede. The origin of these colors is not clear.In March 1979, the Voyager 1 space probe found that Ganymede was light gray, with a reddish area about 130 kilometers long and 200 to 220 kilometers wide.[3]
scientific research
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Galileo detectorThe Galileo probe, which began its Jupiter exploration journey in October 1989, flew over Ganymede, the nearest satellite to Jupiter, for the first time in 2011, and completed the scientific exploration of the magnetosphere in Jupiter's high radiation.The gravity of Ganymede may interfere with the radio transmission of the spacecraft, which may help scientists understand the mass and structure of Ganymede.This is also the last scientific exploration activity of Galileo.However, due to the extremely strong radiation interference encountered when approaching the surface of Jupiter, Galileo stopped all normal operations and the system entered a "safe" mode.All data collected by the detector can be sent back to the ground remote control center only after the technician restarts the system.[3-4]
The last "kiss" between Galileo and Ganymede
GalileoFly over Ganymede at a distance of 160 kilometers.Galileo has approached Jupiter's other satellites 30 times, but it is the first time that it has flown into the orbit of Ganymede.When Galileo arrived at Ganymede, a few seconds after passing Ganymede, Galileo entered the "Gossamer Ring" of Ganymede.Then the spacecraft passed through Jupiter's inner magnetosphere, which was full of various charged particles, and the radiation was very strong.Scientists point out that the data collected by the spacecraft will help to reveal the "secret" of Jupiter's magnetosphere more deeply;Studying Jupiter's "mysterious" ring can help explain why Jupiter failed to become a star, and will also help engineers and technicians to design more powerful exploration spacecraft.[4]
Surface characteristics
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Ganymede is the reddest celestial body in the solar system. It is even redder than Mars.Its red color comes from the sulfur emitted by the volcano on Io.There are also green spots on the main slope of Ganymede. The origin of these colors is still unclear.
Ganymede has an irregular shape. Its three axes are 250 × 146 × 128 kilometers long, and its long axis points to Jupiter.There are many impact craters on its surface. Compared with its size, some of them are very large.The largest Pan impact crater is 100km in diameter and 8km deep;The other crater (Gaia impact crater) is 80km in diameter and twice as deep as Pan.There are also two mountains on Ganymede, which are 20 kilometers higher than other parts.
The size and irregular shape of Ganymede may indicate that it is a very solid object, otherwise its shape will become more round with time.It may be an asteroid captured by Jupiter.Like Jupiter's other moons, Ganymede has the same period of revolution and rotation.Like Io, Ganymede radiates more heat than it receives from the sun, which may be caused by the current induced by Jupiter's magnetic field inside Ganymede.
Impact crater
The impact crater of Ganymede is named after the god of Greek mythology.
On May 13, 2024, NASA released on its official website the photos taken by Juno spacecraft when it flew over Jupiter in a short distance recently, including two photos of Jupiter's small satellite, Ganymede.[5]
