Hua Feng saw that there are 100 to 150 peaks on the surface of Io, with an average height of 6 kilometers, and the highest one is Boösaule Mo in Antarctica

TES, up to 17.5±1.5 km. The peaks are usually huge, with an average length of 157 kilometers, and the isolated structures do not appear to have a global tectonic pattern, just like the peaks on Earth. Io's crust of silicate rocks is necessary to support these massive peaks, compared to a crust made of sulfur.

Although Io's extensive volcanism presents many characteristics, almost all of the mountains have structures that come from crustal movements. Most of the peaks in Io-Io are not caused by volcanoes, but are the result of compressive stresses in the lithosphere, which are raised by the frequent upsetting of the I'o crust and reverse faults.

The compressive stresses that lead to the formation of mountain peaks are the result of the constant burial of material from volcanic deposits. The global distribution of mountain ranges appears to be symmetrical to the volcanic structure, with only a few volcanoes in the peaks, and vice versa. This suggests where the lithospheric structure in large-scale areas is controlled by compression (supporting the formation of mountains) and expansion (supporting the formation of craters). Regional, however, mountains and craters are often close to each other, when faults have formed when the mountains have formed and reached the surface, causing magma erosion.

The peaks on Io, which are usually structures that rise from the surrounding plains, come in a variety of shapes. The plateau is the most ordinary, this structure resembles a large, flat top square mountain with a solid surface. Other mountains appear to be stirred crust, with gentle slopes, formed by the old surface, including steep slopes of surface material, which are the result of compressive stresses on the underlying material. Both types of mountains often have steep slopes that form one or more edges.

Only a few mountains on Io, whose sources appear to be volcanoes, resemble shield volcanoes, with a gentle slope (6–7°) and a small caldera in the center and shallow sloped edges along the vicinity. These volcanoes are generally smaller than the average size of Mount Io, averaging only 1 to 2 kilometers (0.6 to 1.2 miles) in height and 40 to 60 kilometers (25 to 37 miles) wide. There are also several more gently inclined shield volcanoes, which are morphologically inferred to be volcanoes on Io, such as La volcanoes, because of the lava flows radiating from the center.

Almost all of the mountains appear to be in a degraded stage, and large-scale landslide deposition is a common phenomenon in the foundations of the mountains on Io, so collapse is suggested to be the main form of degradation. The common feature of the Fangshan and plateaus in Io is the scallop-like edge, which is the result of the weakening of the edge area of the mountain due to the penetration of sulfur dioxide from the crust of Io.

Auroras glow in the upper atmosphere of Io, and their colors come from different components of the atmosphere (green from sodium atoms, red from oxygen atoms, and blue from volcanic gases such as sulfur dioxide). The image was taken at Io.

The atmosphere of Io, which is extremely thin, only one billionth of the Earth's atmospheric pressure, is mainly composed of sulfur dioxide, but also small amounts of sodium chloride, sulfur monoxide and oxygen.

The thin atmosphere of Io means that future probes landing on Io by any means will not need to be fitted with heat shields to protect the instruments, but will require a repropulsion rocket for a soft landing. The thin atmosphere also made the landing equipment strong enough to resist Jupiter's intense radiation, which also thickened the thin atmosphere.

The same radiation (in the form of plasma) also strips the atmosphere, so it must be replenished frequently. The most striking source of sulphur dioxide is volcanism, but the constant exposure of sunlight to the atmosphere can also sublimate frozen sulphur dioxide. The atmosphere is mainly confined to the equator, where it is the warmest, and most of the active volcanoes that form flow beams are also at the equator. Other variations are also present, with the highest density near the crater (especially the crater with the flow), and the anti-wood point of Io (the farthest point from Jupiter on Io, where the amount of sulfur dioxide frost is the most abundant).

High-resolution images taken by satellites show that astronomers can observe glow-like aurora during the eclipse of the satellite. This phenomenon comes from the interaction of radiation and the atmosphere, like the aurora on Earth. Auroras usually occur near the magnetic poles of planets, but the brightest auroras in Io are located at the equator.

Io itself does not have a magnetic field, therefore, the electrons follow Jupiter's magnetic field to Io and directly hit the moon's atmosphere. The more electrons hit the atmosphere, the brighter the aurora becomes, and the magnetic field lines are tangential to the satellite (that is, close to the equator), so the column of air passing there will be the longest. The combination of the aurora with the tangent point on Io, the observed "shaking", indicates the direction of change in Jupiter's oblique magnetic dipole field.

Io's first observations were made by Galileo on January 7, 1610. The discovery of other Galilean moons of Io and Jupiter was published in Galileo's Astral Report published in March 1610.

Simon Marius, in his 1614 newspaper Marius Jupiter, claimed that he had discovered Io and Jupiter's other moons in 1609, a week before Galileo. Galileo questioned this statement and refuted Marius's plagiarism and plagiarism of his achievements. Because Galileo published his findings before Marius, and it is believed that Marius also knew about it.

For the next two and a half centuries, Io remained unresolved, and remained only a point of light of magnitude 5 in astronomers' telescopes. In the 17th century, Io and other Galileo moons served a variety of purposes, such as assisting crews in measuring longitude, verifying Kepler's third law of planetary motion, and measuring the time it takes for light to travel between Jupiter and Earth. Based on the ephemeris established by Cassini and others, Laplace created a mathematical theory to explain the orbital resonances of Io, Europa, and Gaymede. This resonance was later discovered to have a profound impact on the geology of the three moons.

Improvements in telescope technology enabled astronomers in the late 19th and early 20th centuries to analyze (see) the surface characteristics of large areas in Io.

In the 1890s, Barnard first observed the photometric variation between the equator and the polar regions of Io, and correctly measured that the photometric variation between the two regions was due to differences in color and albedo, not because Io was oval, as William Pickering and his companions had argued, rather than two different objects as Barnard had originally claimed. Later telescope observations confirmed that Io was clearly reddish-brown in the polar regions and yellowish-white in the equatorial zone.

In the mid-20th century, telescopic observations began to note the nature of the Io anomaly. Spectroscopic observations suggest that the surface of Io is free of water ice (a substance found in abundance on other Galileo moons), and that the main components of the surface are sodium and sulfur. Observations by radio telescopes have revealed that Io has an effect on Jupiter's magnetosphere, such as the observed 10-meter wavelength explosion related to Io's orbital period.

The first spacecraft to pass through Io were twin spacecraft Pioneer 10 and Pioneer 11, which radio-tracked on December 3, 1973 and December 2, 1974, respectively, provided an improved estimate of the I'o mass, and the best value for the size of the Io. Io is thought to be the densest of the four Galilean moons, and is composed mainly of silicate rocks rather than water ice.

The Pioneer also revealed that Io has a thin atmosphere and a strong radiation belt near its orbit. The only good picture ever obtained by the camera of Pioneer 11 shows the Arctic region of Io. Pioneer 10 was originally planned to take photographs at close range to Io, but this observation failed due to the high radiation environment.

When another pair of spacecraft, Voyager 1 and Voyager 2, passed over Io in 1979, their more advanced imaging systems could have yielded better images.

Voyager 1 flew past the satellite from 20,600 kilometers on March 5, 1979, and it returned images that revealed strange, colorful images without impact craters. The highest-resolution images show a relatively young surface dotted with oddly shaped pits, a mountain higher than Everest, and features that resemble lava flows.

After a brief encounter, Voyager engineer Linda Monabedore noticed a stream radiating from the surface in one of the images. Analysis of other images taken by Voyager 1 revealed a total of nine photographs with such beams, confirming active volcanic activity in Io.

Shortly before Voyager 1 meets Io, Sta

Peale、Pat

ick Casse

, and R. T. Rey

Olds has published a paper in which the author calculates that due to the orbital resonances of Europa and Gaymede, there will be a great amount of tidal heating inside Io (see the Tidal Heat section for a detailed process and explanation). Data from this flyby shows that Io's surface is dominated by sulfur and sulphur dioxide frost. These components also control the rarefied atmosphere and the ring of plasma that orbits Io (also discovered by travelers).

Voyager 2 passed by 1,130,000 km (702,150 mi) on July 9, 1979, and although he was not as close as Voyager 1, imagery comparing the two spacecraft shows that some areas of the surface have changed during the five-month period. On the other hand, Voyager 2 observed a crescent-shaped Io as it left Jupiter's system, and showed that 8 of the 9 beams observed in March were still active, with only the Peret volcano extinguished.

The Galileo spacecraft arrived at Jupiter in 1995 after a six-year voyage from Earth, following the discoveries of the Voyager spacecraft and ground-based astronomy

Taiwan has been observing for many years, and the follow-up observations are continued. Io's position within one of Jupiter's strongest radiation belts hinders long-term close-range observations, but Galileo's main mission was to study Galileo's moons, and during the first two years of his mission, his orbit would enter and pass through these moons closely. Although no images were obtained during the flyby on December 7, 1995, there were significant results, such as the discovery of a huge iron core similar to a rocky planet in the inner solar system.

During Galileo's main mission, despite the lack of close-up shots and mechanical problems, a lot of material was sent back and some important discoveries were made. Galileo observed Pilla

The main eruptions of the volcano, and confirmed volcanic eruptions, consist of silicate rock plasma and magnesium-rich mafic and ultramafic components with sulfur and sulfur dioxide, similar to the role played by water and carbon dioxide on Earth.

During the main period of the mission, nearly every orbit was imaged from a distance, revealing a large amount of volcanic activity (the rock plasma from both the surface and the volcanic flow beam emit radiant heat as it cools), numerous mountains, and extensive morphological changes, as well as changes in the surface between the ages of Voyager and Galileo, as well as during Galileo's different orbits.

During the extended mission of Galileo in 1997 and 2000, the spacecraft flew by Io-Io three times in late 1999 and early 2000 and three more times in late 2001 and early 2002. Observations at the time of these encounters reveal the geological processes of the volcanoes and mountains of Io, rule out the presence of magnetic fields, and confirm the extent of volcanic activity. In December 2000, the Cassini spacecraft made a brief encounter with the Jupiter system on its way to Saturn, where it was observed in conjunction with Galileo. This observation discovered a new stream beam in the Twastasta crater and confirmed the observation of the Aurora Aurora in Io.