What Hua Feng didn't expect was that he thought he would have the opportunity to directly reach the second home of the earth, but when he was about to land, Sun Xing suddenly appeared and said: "We are going to transfer to Jupiter's moon group, because the dignitaries and elites of the Titan countries are currently among them, and for the sake of safety, they are temporarily denied login." ”

Although Hua Feng and the others were not very happy in their hearts, the current situation forced them to change their route.

In Hua Feng's impression, Jupiter's 13 moons are divided into three groups. The closest group to Jupiter, Ganymede and the four Galilean moons, have very small orbital eccentricities (≦0.01), and the angle of intersection between the orbital plane and the equatorial plane of Jupiter is also very small (≦05), that is, they all move in circular orbits on the equatorial plane of Jupiter, and the orbital plane of these moons is about 2°~4° of the orbital plane of Jupiter. The rest of the satellites are irregular, but they can be divided into two groups.

A group of moons slightly farther away from Jupiter, Callisto, Callisto, and Ganymede have an angle of 24°~29° between the orbital plane and the equatorial plane, and are anterograde, with an orbital eccentricity of 0.13~0.21. The farthest group of Jupiter, Callisto, Callisto, and Europa have a fairly large orbital eccentricity (0.17~0.38), and their orbital planes are at an angle of 145°~164° to Jupiter's equatorial planes, and they are all retrograde moons. Some believe they may be asteroids captured by Jupiter.

The following phenomena will occur in the operation of Jupiter's moons: Jupiter has a shadow cone in the direction of the sun under the sun, and when the moon of Jupiter enters the shadow cone, the moon cannot reflect the sun's light and becomes invisible, which is called a Ganymede eclipse. When Jupiter's moons enter the back of Jupiter's circle, our view of Jupiter's moons from Earth is blocked by Jupiter, which is called a Callisto occultation.

Jupiter's moons pass in front of Jupiter's circle and cast a circular spot on Jupiter's apparent circle as seen from Earth, called Callis. When the shadow of one of Jupiter's moons is cast on Jupiter's apparent circle and it is not itself on Jupiter's apparent circle, it is called Ganymede. When seen from Earth, when one of Jupiter's moons blocks the other, it is called a Ganymede occultation, and when one Ganymede enters another Ganymede's shadow cone, it is called a Europa eclipse.

Jupiter's four larger moons, the Galilean moons, are listed from the inside to the outside as Io and Europa (Eu).

opa), Ganymede (Ga

ymede), Callisto, which, together with Jupiter, form a small "solar system". The motion of Galileo's moons around Jupiter has been of great concern to astronomers.

The orbital models of these satellites can be improved through continuous observations, thus providing the necessary support for in-depth exploration of Jupiter and its surrounding space environment. In recent years, Jupiter and its moons will have multiple occultation and eclipses. Mutual occultation can occur when the Earth and Galileo satellites are in the same orbital plane, and similarly, mutual eclipse can occur when the Sun and Galileo satellites are in the same orbital plane.

For Galileo's moons, this occultation occurs once every 6 years, Saturn's moons every 15 years, and Uranus's moons only once every 42 years.

At the end of 1608, Galileo saw a telescope for the first time, and he soon realized that what astronomers needed most was a high-powered telescope. At the end of 1609, Galileo Galilei built a 40x double-lens telescope. It was the first telescope for astronomical observation in scientific research.

Johannes Kepler described the orbits of the planets in a paper in which Galileo believed the "heliocentric theory" of the Polish astronomer Nikolaus Copernicus. It is dangerous to believe in the "heliocentric theory", because believing in the "heliocentric theory", Gionano Bruno was burned alive at the stake. Galileo decided to use a new telescope to map the planets more accurately, proving that Copernicus' "heliocentric theory" was correct.

Galileo used a telescope to observe the moon first. He could clearly see the mountains and valleys of the moon, the jagged edges of the moon that looked like they were cut with a serrated knife.

The moon he observed was not as smooth as Aristotle and Ptolemy claimed. But the powerful Catholic Church, university teachers and scientists in Europe were convinced of the theories of Aristotle and Ptolemy. By observing the surface of the moon overnight, Galileo once again proved Aristotle's theory wrong.

Galileo once proved the law of free fall motion because it contradicted Aristotle's theory, and he was dismissed from his teaching position.

Galileo's next target was Jupiter, the largest planet, and he planned to spend several months carefully mapping Jupiter's orbit. Through a telescope, Galileo observed space that man had never observed, and Jupiter was clearly observed. To his surprise, he found several moons orbiting Jupiter. Aristotle once said (and all scientists think so) that only the Earth has satellites in the universe. In the days that followed, Galileo discovered four moons of Jupiter, the first to be discovered outside of Earth. Once again, he proved Aristotle's theory wrong.

However, old ideas won't fade away anytime soon. In 1616, the Catholic Church forbade Galileo from teaching and forbade him to preach Copernicus' theories. Many high-ranking leaders of the church refused to use telescopes to observe space, claiming that it was a magician's trick and that satellites only existed in telescopes.

Galileo ignored the Church's warnings and was eventually recalled to Rome by the Inquisition, where he was tortured. He was forced to retract his views and findings, and was sentenced to life in prison. In 1640, Galileo died, and before his death he did not say anything other than that his findings were correct. October 1992 – 376 years after Galileo was wrongly sentenced, the Church of Rome rehabilitates him and acknowledges his scientific discoveries.

The density of the four Galilean moons decreases with distance from Jupiter, much like the density of the planets in the solar system varies with distance from the Sun. This condition in the solar system is caused by the evaporation of lighter and volatile substances using the primordial sun as a heat source. Pollac argues that the same process took place with Jupiter and its moons, but with the primordial Jupiter as the heat source. Jupiter currently radiates twice as much heat energy as it receives from the Sun. And in the first few million years of Jupiter's birth, Jupiter radiated an average of one hundredth of the energy radiated by the Sun today.

The surface of Europa is covered with evaporating sodium salts (which may be crystals of the usual salts). The surface of Europa, Europa, and Europa is covered with salt and sulfur to varying degrees, in addition to gravel soil and frost. Europa is basically a rock structure, and Europa's rock mass is covered with a crust made of water ice.

Based on the density of Ganymede and Ganymede, Lewis believes that no more than 15% of the rock or silicon minerals in these two moons, and most of the rest is made up of frozen water, ammonia and methane. R.A. Brown announced in 1973 that he had observed sodium gas in Io's emission spectrum, and other observers later confirmed the existence of an atmosphere composed of sodium gas and other components in Io.

This atmosphere stretches out far beyond the limits of its gravitational pull in the space around Io. It turns out that the surface of Io is covered with volatile sodium salts, which evaporate due to sunlight heating and permeate Io's orbit, forming a circular sodium cloud. The Pioneer 10 space probe also observed a hydrogen cloud in Io's orbit that is much larger than a sodium cloud, and a vast ionosphere on the sunny side of Io that is large enough to be compared to the ionosphere of Venus and Mars.

Astronomy is often understood simply as the application of existing laws of physics to explain observed astronomical phenomena.

In fact, because the various strange states in which celestial bodies are located provide a large number of physical states that cannot be realized on the ground, a large number of astronomical observations actually provide observational facts for the establishment of new physical laws, such as the establishment of Newton's formula of universal gravitation, which is based on Kepler's three laws of planetary motion. The phenomenon of optical travel related to the establishment of the theory of relativity was also first discovered in astronomical observations.

An important constant in modern physics was also obtained in 1676 by the French astronomer Romer from his observations of Europa. From all the observations made of light propagation, we know that the speed of light is enormous, and Galileo tried to measure this speed with light signals, but was unsuccessful, because it only took a very short time for light to pass a distance on the ground. Therefore, the only way to make such a successful measurement is to make use of the enormous distances between celestial bodies in astronomical space.

A solar eclipse occurs whenever a moon enters Jupiter's shadow. If there is an observer on Jupiter who thinks that every once in a while t there will be a lunar eclipse, t is equal to the time it takes for the moon to make one revolution around Jupiter. If L is the distance from Jupiter to Earth, then it will take a period of time for this signal to reach Earth.

If let l denote the amount of change in distance L over the time it takes for the satellite to make one revolution, then the time interval between each adjacent satellite eclipse will appear slightly different to the observer on Earth, and it will be t+l/c

The time required for the lap is equal to t

=Nt+l

/C where I

It's on the satellite

The total amount of change in distance L over the time of the lap.

Here are two unknowns t and c, which can be determined from two appropriately chosen observations. First, the distance L between the Earth and Jupiter passes a certain time t

。 and then they were just as far apart. We can estimate this time interval t

。 The number of satellite eclipses that occur within N. Because Jupiter moves relatively slowly, it can be approximated that it depends only on the Earth's orbital position

。 Take the time it takes for the Earth to make one revolution around the Sun, i.e., one year. From this, t can be obtained.

Second, we start from the closest position of the Earth and Jupiter to each other, and count the number of lunar eclipses N' in a half-year period, where l'N is equal to the diameter of the Earth's orbit (i.e., about 3×108 km per astronomical unit). From this we can calculate t'N=N't+l'N/c. The observed delay time t'N-N't is 17 minutes, i.e. about 1000 seconds, and C = 300,000 km/s, which is very close to the exact value of the speed of light.

Discovered by Bradley in 1727. Another effect caused by the finite speed of light is the phenomenon of light travel. That is, all stars seem to be in a common annual motion, which clearly corresponds to the Earth's motion around the sun. It is easy to understand this phenomenon from the point of view of particles. If the Earth is stationary, then in order to observe a celestial body, we must point the telescope lens directly at that object, conversely, if the Earth is moving to the right, the telescope lens must be tilted at an angle as shown in B. The study of the propagation properties of light led to the emergence of the special theory of relativity.

According to the news released by American astronomers, Jupiter, the planet with the most moons in the solar system, has been discovered and two new moons, which were discovered by Shepard of the Carnegie Institution in September 2011.

According to reports, the diameter of these two new moons is only 1 to 2 kilometers, which is smaller than the moon and irregular shape, one of them is about 2,000 kilometers away from Jupiter, and it orbits in about 582 days. The other is about 2,300 kilometers away from Jupiter and orbits for about 725 days.

Scientists say that 52 of Jupiter's 66 moons orbit in the opposite direction of Jupiter's rotation and are mostly located in the far outer regions, so scientists deduce that these moons are comets or asteroids captured by Jupiter's gravity and are not Jupiter's native moons.