Saturn's rings are composed of countless small objects, which revolve around Saturn on Saturn's equatorial plane. Saturn is also a planet in the solar system with the number of satellites second only to Jupiter. There are many large and small satellites around it, just like a small family. In recent years, with the continuous improvement of observation technology, the number of planetary satellites has risen sharply, and more than 6 Saturn satellites have been discovered so far. Saturn's moons have various shapes, which make astronomers have great interest in them. The most famous "Titan" has an atmosphere, and it is one of the known satellites with atmosphere in the solar system.
Saturn has a remarkable ring system, which is mainly composed of ice particles, less rock debris and dust. There are 62 confirmed satellites of Saturn, 9 of which were discovered before 19. Among them, Titan is the largest satellite in Saturn's system and the second largest satellite in the solar system (with a radius of 2575KM) (the largest satellite in the solar system is Jupiter's Ganymede with a radius of 2634KM), which is larger than Mercury in the planet; And Titan is the only satellite with an obvious atmosphere. From near to far from Saturn, Titan to Titan are arranged as follows: Titan, Titan, Enceladus, Titan, Titan, Titan, Titan, Titan, Titan, Iapetus, and Titan. The distance between Enceladus and Saturn is only 159,5 kilometers, which is only 2.66 times of Saturn's equatorial radius, and it is close to roche limit. These satellites revolve around Saturn in a near-circular orbit near Saturn's equatorial plane.
Saturn has many moons. The exact number is uncertain. All the large ice cubes on the ring are satellites in theory, and it is difficult to distinguish between large particles and small satellites on the ring. By 29, there were 62 confirmed satellites, of which 52 had official names; There are still three possible aggregates of dust on the ring that have not been confirmed. Many satellites are very small: 34 satellites are less than 1 kilometers in diameter and 13 satellites are less than 5 kilometers in diameter. Only 7 satellites have enough mass to achieve hydrostatic balance by their own gravity.
In p>198, when Voyager flew over Saturn, eight new satellites were discovered on the basis of the original nine satellites (Enceladus, Enceladus, Enceladus, Enceladus, Titan, Titan, Enceladus and Titan). But it's hard to say how many moons Saturn has. Some of the larger particles that make up Saturn's rings may actually be small satellites. Saturn has the most satellites in the solar system. Unlike Jupiter's moons, Saturn's moons cannot be simply classified by composition and density. The satellites discovered by Voyager show complex and diverse features.
Except for Titan, the data sent back by astronomers from the Voyager spacecraft found that Saturn's other moons are relatively small, and all of them have meteorite scars on the cold surface, like broken eggshells. There is a crater with a diameter of 128 kilometers on the surface of Enceladus; Enceladus has desolate plains, craters and wrinkled ridges, and its different regions represent different historical periods; There is a deep and wide rift valley about 8 kilometers long on Titan. There are sparse and bright stripes on the surface of Titan, all of which surround the crater. On March 25th, 1655, Dutch astronomer Huygens, while observing Saturn with a self-made 3.7-meter-long refracting telescope, stumbled upon a satellite of Saturn, which was named Titan. It is Titan, which attracts the most attention of astronomers, and is the first Saturn satellite discovered by human beings.
among Saturn's moons, Titan is one of the celestial bodies that astronomers pay attention to. For a long time, Titan has been regarded as the largest satellite and the only satellite with an atmosphere in the solar system, and its atmospheric composition is mainly methane. It used to be thought that its surface temperature was not very low, so people speculated that there might be life on it. The data sent back by voyager 1 is disappointing. It is found that Titan is only 5,15 kilometers in diameter, which is not the largest satellite in the solar system (Ganymede has the largest diameter of 5,262 kilometers). It has a dense atmosphere and a liquid surface. Its atmosphere is at least 4 kilometers thick, with methane content less than 1%. The main component of the atmosphere is nitrogen, accounting for 98%, and a small amount of ethane, ethylene and acetylene. Titan's surface temperature is between -181℃ and -28℃, and there is an ice mantle and a rock core under the liquid surface. The spacecraft found no trace of life. Titan can send out radio waves, which is confusing. In addition, there is a hydrogen cloud near Titan's orbit.
For a long time, Titan has been regarded as the largest satellite in the solar system, surpassing Mercury. A close-range measurement by Voyager took five high-resolution photos at 35, kilometers. Titan in the photo shows a beautiful orange-red star, like a ripe orange. More importantly, the data received rewrote Titan's original diameter of 5,8 kilometers, and the actual diameter should be 5,15 kilometers. It was forced to transfer the crown of "king of satellites" to Jupiter's satellite Ganymede, ranking second. This has not affected its status. Scientists have always been interested in Titan because it is the only celestial body in the satellite with an atmosphere. The main component of the atmosphere is nitrogen, accounting for about 98%, methane accounting for 1%, and the rest of the hydrocarbons account for a very small proportion in the atmosphere, and the thickness of the atmosphere is about 27 kilometers. Titan's surface temperature is very low, ranging from-19℃ to-21℃, making it a beautiful ocean of liquid nitrogen.
Although we can't see the surface of Titan, the information provided by Voyager shows that Titan is another strange world in the solar system, with a dark and cold surface, a sea of liquid nitrogen, a dark red sky and occasional nitrogen rain mixed with hydrocarbons. These are the ideal places for human beings to understand the origin of life and various chemical reactions.
It has been more than 3 years since Huygens discovered Titan, and Titan is still a mystery to be solved. If we want to have a deeper understanding of Titan, we need human beings to continue to explore.
why do astronomers pay special attention to titan? Titan is favored and valued by astronomers because of its outstanding talent. Titan's unique "talent" is shown in the following aspects:
First of all, Titan's diameter is about 5,15 kilometers, ranking second in the satellite world, much larger than Pluto and about the size of Mercury. Its mass is 1.8 times that of the moon, its average density is 1.9 grams per cubic centimeter, which is about 1/3 of the density of the earth, and its gravity is 14% of that of the earth.
The average distance between Titan and Saturn is 1.22 million kilometers, and it moves around Saturn in a nearly circular orbit. Like the moon, it always faces its planet Saturn in the same direction. In other words, if you look at Titan from Saturn, you can always see only the same half of Titan. Its orbit is basically in Saturn's equatorial plane. You can think about it. It's hard to imagine that an object as big as Titan moves in a nearly perfect orbit along a radius of about 1.22 million kilometers. I'm afraid it's not easy to draw such a circle. It shows the natural wonders in the evolution of celestial bodies.
second, in 1944, the Dutch-American astronomer kuiper made a systematic spectroscopic observation of Titan, and found that there was methane gas on Titan, thus confirming that there was a dense atmosphere on Titan. Titan is still the only satellite with atmosphere among more than 1 satellites known in the solar system. How can it not be particularly favored by astronomers?
Thirdly, according to the movement characteristics, physical condition and chemical composition of Titan, astronomers determine that Titan evolved with Saturn and belongs to a stable satellite, so it can't be a small celestial body captured by Saturn later. At one time, some astronomers compared Titan's celestial characteristics and celestial environment with the Earth, such as mass, volume, surface gravity, surface temperature, atmospheric composition, water and ice content, rotation and revolution, in order to get clues about the evolution of early life materials.
is there any life on other celestial bodies? This question has been lingering in the minds of astronomers. Huygens, the discoverer of Titan, wrote in the book Wonders of Celestial Bodies, Speculations about Residents, Plants and Their Worlds on Other Planets: If we think that there is nothing on these celestial bodies except boundless desolation ... < P > and even further think that there is no advanced life there at all, then we will belittle them, which is very unreasonable. It is true that it is a very serious scientific problem to judge whether there is life on any celestial body. Judging from the level of modern science and technology, I'm afraid it's unrealistic to be too optimistic, but it's also unfounded to be too pessimistic. Practice is the only criterion to test the truth. As for the life information on Titan, it is still a mystery that is not optimistic, but it will be solved in the practice of continuous exploration.
from the earth, titan is an 8.4-magnitude star. You can't see it directly with your eyes. Observing it with a good astronomical telescope, you can only see a small red dot-like disk. Why is this color? Some people think that this may be because there are complex organic molecules on Titan. Of course, relying entirely on ground observation can't solve this kind of problem, and it can only be "an armchair strategist".
With the rapid development of aerospace industry, the interplanetary probes have made unprecedented achievements. As of 213, there are three interplanetary spacecraft that have personally explored Titan. They are Pioneer 11 and voyager 1 launched by the United States and Huygens launched by Europe.
On September 1st, 1979, Pioneer 11 flew by Saturn and inspected Titan. However, when Pioneer 11 visited Titan, it was catching up with a strong solar wind, which seriously affected the information sent back. The ground control center only received five high-resolution photos it took at a distance of 35, kilometers. In the photo, Titan appears beautiful orange-red, like a ripe orange. Voyager 1 flew to Titan on November 11th, 198, and the exploration was a complete success. It was this time that Titan was measured to be 4,828 kilometers in diameter, instead of 5,55 kilometers as previously thought.
voyager 1's investigation on Titan shows that Titan does have a thick atmosphere, about 2,7 kilometers thick, which is higher than the density of the earth's atmosphere. The main components of the atmosphere are nitrogen, accounting for 98%, methane accounting for 1%, and a small amount of ethane and hydrogen. There are also nitrogen in the atmosphere of Venus, Earth and Mars, but they are not as much as Titan.
voyager 1 also found that Titan's atmosphere was foggy. The dense fog layer prevented sunlight from reaching the surface of Titan, which affected voyager 1's observation of Titan's surface. At the same time, some scientists believe that Titan's atmosphere is full of methane according to the observation data of voyager 1.
In order to further study the relationship between Titan's atmosphere and life, carl sagan, a planetary physicist at Cornell University in the United States, and others made a simulation experiment of Titan's atmosphere. Researchers believe that Titan's atmosphere, which contains a lot of nitrogen, produces a variety of pre-life chemicals. Sagan pointed out: "A similar process may have happened on the early earth. However, the pre-life chemical process that took place on Titan is probably lifeless because the temperature there is far below the freezing point of water. "
Speaking of which, have you ever thought: Why is Titan the only satellite with such a rich atmosphere? This has always been a question that planetary physicists are thinking about. Some people think that this may be because the surface temperature of Titan is high enough to maintain a considerable amount of methane and ammonia to keep the ice on its surface in balance. It is also possible that the ice on Titan contains methane and ammonia, which is easy to form the atmosphere at the temperature of Titan. The third possibility is that Titan's atmosphere will not escape like Jupiter's strong magnetic field. The fourth possibility is that Titan has a large mass and can undergo internal differentiation. The differentiated ice is concentrated on the surface, and its gravity is enough to keep most of the gas from running away.
So far, only four probes, Pioneer 11, voyager 1 2 and Cassini-Huygens, have flown to Saturn to explore Saturn. On September 1, 1979, Pioneer 11 became the first probe to visit Saturn after a six-and-a-half-year space journey. It flew over 22 kilometers from Saturn's cloud top, explored Saturn for 1 days and sent back the first photos of Saturn. Pioneer 11 not only discovered two new rings of Saturn and Saturn's 11th satellite, but also confirmed that Saturn's magnetic field is 6 times stronger than that of the earth. On September 2, it crossed the plane of Saturn's ring for the second time, and turned to Titan by Saturn's gravity, thus detecting this planet that may be pregnant with life.
On November 12th, 198, voyager 1 flew over 12,6 kilometers away from Saturn, and sent back more than 1, color photos. This exploration not only confirmed the existence of Enceladus 1, 11 and 12, but also discovered three new Saturn moons. When it flew less than 5 kilometers away from Titan, the atmosphere of Saturn's largest satellite was detected and analyzed for the first time. It was found that there was neither enough water vapor in Titan's atmosphere nor enough liquid water on its surface.
On August 25th, 1981, Voyager 2 flew over 1,1 kilometers from Saturn's cloud top and sent back more than 18, photos of Saturn. It is found that the surface of Saturn is cold and windy, and there are strong and stable storms in the high latitudes of the northern hemisphere, even more fierce than those on Jupiter. Saturn also has a great red spot, 8 kilometers long and 6 kilometers wide, which may be caused by the disturbance and rotation caused by the updraft in Saturn's atmosphere falling into the clouds again. From time to time, lightning passes through Saturn's rings, which is tens of thousands or even hundreds of thousands of times more powerful than lightning on earth. It once again confirmed that Saturn has seven rings. Saturn's rings are composed of particles and gravel with a diameter of several centimeters to several meters. The particles in the inner ring are smaller, and the particles in the outer ring are larger. Because of the different particle densities, the rings show different colors. Each ring can be subdivided into thousands of small rings, even if it is considered empty, there are several small rings in Cassini seam. In high-resolution photos, you can see that F ring has five small rings intertwined with each other. The overall shape of Saturn's rings is similar to a huge compact record, extending from Saturn's cloud top to 32 thousand kilometers away. Voyager 2 discovered 13 new moons of Saturn, bringing the number of Saturn's moons to 23. It inspected nine of the satellites and found that there is a large crater on the surface of Titan, with a diameter of 4 kilometers, and the bottom rises upward in a dome shape, and there is a huge crack that surrounds this satellite for almost 3/4 weeks. One hemisphere of Iapetus is dark and the other hemisphere is very bright; Titan's rotation period is only 9-1 hours, which is far from its period of revolution of 55 days. Titan's actual diameter is 4,828 kilometers, instead of 5,8 kilometers as originally thought. It is the second largest satellite in the planets of the solar system. It has a dark and cold surface, a sea of liquid nitrogen, a dark red sky, and occasional nitrogen rain mixed with hydrocarbons. This is an ideal place for human beings to understand the origin of life and various chemical reactions.
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