Jupiter's irregular satellite 5 letters. Success! An artificial satellite first entered Jupiter's orbit (5 photos)
MOSCOW, September 24 - RIA Novosti. Historians have found in one of the London libraries the original letter in which Galileo Galilei outlined his arguments against the geocentric doctrine of the Catholic Church, which became the reason for the accusation of heresy. This discovery was reported by the news service of the journal Nature.
"Surprisingly, these letters were not hidden - they lay open in the library of the Royal Society of London. Nobody noticed them for several centuries, as if they were invisible or transparent. I am glad that we were able to find one of the first." declarations of independence of "science from religion," said Franco Giudice of the University of Bergama.
Fire of enlightenment
Galileo Galilei, along with Giordano Bruno and Nicolaus Copernicus, are traditionally considered one of the first "martyrs of science", whose lives were cut short or seriously affected by the conflict between their scientific interests and the tenets of the Catholic Church.
The main stumbling block in all these cases was the concept of how the solar system and space work. The church adhered to the Ptolemaic geocentric model, in which the Earth was recognized as the center of our planetary family and the entire universe as a whole, while the three founders of modern astronomy questioned this postulate.
In 1610, Galileo discovered the phases of Venus, the moons of Jupiter and some other celestial bodies and phenomena that did not fit into the doctrines of the Catholic Church. Initially, his discoveries and books did not attract the attention of the church and the public, but then the situation changed dramatically.
In the fall of 1613, Abbot Benedetto Castelli, a close friend and disciple of Galileo, wrote him a letter in which he told how he had to defend the astronomer from the attacks of the supporters of the "biblical" view of the world. In a response letter, Galileo, as Castelli himself later noted, responded to "theological" criticism and talked about why science and the church should be separated.
This letter, as noted by Giudice, "leaked" into the general public and caused a powerful resonance, becoming the starting point in the Inquisition against Galileo. Its original was considered lost, and Galileo himself claimed that part of the copies of the letter circulating in the church and secular community were forged. For this reason, historians have long debated what Galileo really wrote and whether his words were distorted.
Scientific self-censorship
Giudice and his colleague Salvatore Ricciardo from the University of Cagliari accidentally found the original of this letter while analyzing the comments of contemporaries in the margin of Galileo's works. In early August, they studied catalogs of documents stored in the library of the Royal Society of London - one of the first scientific academies in the world.
In one of these catalogs, Ricciardo and Giudice found references to a letter from an "unknown author" that Castelli received in December 1613. Looking at photographs of this text, Italian historians noticed the initials "G. G." and suggested that its author was Galileo Galilei.
After convincing the library management to show them all seven pages of this letter, the scientists compared it with other letters of Galileo and confirmed that it was indeed written by the great astronomer. After reading it, the researchers found that the "heretic" made a lot of changes to the text, noticeably softening its content.
These amendments, according to Giudice, indicate that initially Galileo did not want to go into conflict with the Catholic Church and made all critical wording as streamlined as possible. For example, he dropped the accusations that the Scriptures contradict the truth and hide it from Christians.
All this, however, did not help Galileo - his books were officially banned, and the astronomer himself was deprived of the right to teach, express his thoughts and defend the "Copernican heresy" just three years after the letter was published.
Another 16 years later, he was formally convicted by the Inquisition and placed under house arrest after the publication of his major work, Dialogues on the Two Major Systems of the World, which the church hierarchs considered a mockery of Pope Urban VIII.
Open up the champagne! Humanity has a good reason to celebrate. On June 5, Jupiter became much closer to us. At 4:53 am, NASA's Juno spacecraft successfully entered orbit the gas giant. This is the incredible result of a five-year mission that gave Jupiter its first artificial satellite.
During this time, Juno managed to overcome 2.8 billion kilometers in the solar system. This spacecraft is powered only by solar energy, and it is the first in the world to cover such a huge distance from Earth. Now he begins his impressive scientific mission to Jupiter.
On the night of June 4-5, Juno began burning its engines for 35 minutes. This helped it slow down enough to enter Jupiter's orbit. Fortunately, this maneuver passed without any complications.
This news was shared by Scott Bolton, Juno's Principal Investigator, at a NASA press conference.
Scientists' plans for the next 1.5 years
Juno was able to fly closer to Jupiter than any other artificial satellite. It is now in a high elliptical orbit, just a few thousand kilometers above the clouds.
Juno will be in this initial orbit for 53 days, but will be moved to a shorter 14-day orbit on October 19. It is there that he must begin his scientific operations, using the equipment to "look" inside Jupiter and find out what it is made of. Scientists hope to find out if the gas giant has a solid core or not. Scientists are also going to measure the water content to determine if the planet was formed in its current orbit, or even further from the Sun. This will give them insight into the formation of our own planet.
Entering the atmosphere of Jupiter
In total, Juno must complete 37 orbits of Jupiter before entering its atmosphere in February 2018. This will prevent it from colliding with one of Jupiter's moons. But apart from scientific instruments, Juno also has a camera that will take a huge amount of images throughout the mission. The general public will have the opportunity to see everything that the NASA camera recorded on a website specially created for this.
Thanks to the successful combustion of the engines on Monday night, we can count on all of these results over the next year and a half. Thus, Juno became the first messenger of humanity to Jupiter.
Jupiter can rightfully be called the most "weighty" planet in the solar system, because if you add together all the other planets, including our Earth, their total mass will be 2.5 times less than that of this giant. Jupiter possesses very powerful radiation, the level of which in the solar system is exceeded only by the sun.
Everyone knows the rings of Saturn, but Jupiter also has a lot of moons. To date, scientists know exactly 67 such satellites, of which 63 are well studied, but it is assumed that Jupiter has at least a hundred satellites, and most of them have been discovered in recent decades. Judge for yourself: at the end of the 70s of the 20th century, only 13 satellites were registered, and later on, ground-based telescopes of the new generation made it possible to detect more than 50 more.
Most of Jupiter's moons have a small diameter - from 2 to 4 km. Astronomers classify them as Galilean, internal and external.
Galilean satellites
The largest moons of Jupiter: Io, Europa, Ganymede and Callisto were discovered by Galileo Galilei in 1610, and they got their name in honor of him. Their formation took place after the formation of the planet, from the gas and dust that surrounded it.
And about
Io got its name in honor of the beloved Zeus, so it would be more correct to speak of her in the feminine gender. It is the fifth moon of Jupiter and is the most volcanically active body in the solar system. Io is about the same age as Jupiter itself - 4.5 billion years. Like our Moon, Io is always turned to Jupiter with only one side, and its diameter is not much larger than the lunar one (3642 km versus 3474 km for the Moon). The distance from Jupiter to Io is 350 thousand km. It ranks fourth in size among the satellites in the solar system.
On the satellites of the planets, and on the planets of the solar system themselves, volcanic activity is extremely rare. Currently, only four space bodies are known in the solar system where it manifests itself. This is Earth, Neptune's satellite Triton, Saturn's satellite Enceladus and Io, which is the undisputed leader in this four in terms of volcanic activity.
The scale of the eruptions on Io is such that it can be clearly seen from space. Suffice it to say that sulfuric magma from volcanoes erupts up to 300 km (12 such volcanoes have already been discovered), and giant lava flows have covered the entire surface of the satellite, with a wide variety of colors. And in the atmosphere of Io, sulfur dioxide predominates, which is due to high volcanic activity.
Real picture!
Animation of the eruption in Pater Tvashtar, composed of five images taken by the New Horizons spacecraft in 2007.
Io is quite close to Jupiter (by cosmic standards, of course) and constantly experiences the massive effect of its gravity. It is gravity that explains the tremendous friction inside Io, caused by tidal forces, as well as the constant deformation of the satellite, heating its interior and surface. In some parts of the satellite, the temperature reaches 300 ° C. Along with Jupiter, Io is influenced by the forces of gravity from two other satellites - Ganymede and Europa, which mainly causes additional heating of Io.
The eruption of the Pele volcano on Io, captured by the Voyager 2 spacecraft.
Unlike volcanoes on Earth, which most of the time "sleep" and erupt only for a fairly short period of time, volcanic activity on the incandescent Io is not interrupted, and peculiar rivers and lakes are formed from the flowing molten magma. The largest molten lake known today has a diameter of 20 km and contains an island of solidified sulfur.
However, the interaction of the planet and its satellite is not one-way. Although Jupiter, thanks to its powerful magnetic belts, takes up to 1000 kg of matter from Io every second, which almost doubles its magnetosphere. The movement of Io through its magnetosphere generates such powerful electricity that violent thunderstorms rage in the planet's upper atmosphere.
Europe
Europe got its name in honor of another beloved of Zeus - the daughter of the Phoenician king, whom he abducted in the form of a bull. This moon is the sixth farthest from Jupiter, and is about the same age as it, that is, 4.5 billion years. However, Europa's surface is much younger (about 100 million years), so there are practically no meteorite craters on it, which appeared during the formation of Jupiter and its satellites. Only five such craters with a diameter of 10 to 30 km were found.
Europa's orbital distance from Jupiter is 670,900 km. The diameter of Europa is smaller than that of Io and the Moon - only 3100 km, and it is always turned to its planet with one side.
The maximum surface temperature at the equator of Europe is minus 160 ° C, and at the poles - minus 220 ° C. Although the entire surface of the satellite is covered with a layer of ice, scientists believe that it hides a liquid ocean. Moreover, researchers believe that some forms of life exist in this ocean thanks to thermal springs located next to underground volcanoes, that is, the same as on Earth. By the amount of water, Europe is twice ahead of the Earth.
Two models of the structure of Europe
The surface of Europa is riddled with cracks. The most common hypothesis explains this by the influence of tidal forces on the ocean coast below the surface. It is likely that the rise of water under the ice higher than usual occurs when the satellite approaches Jupiter. If this is true, then the appearance of cracks on the surface is precisely caused by the constant rise and fall of the water level.
According to a number of scientists, sometimes water masses break through the surface, like lava during a volcanic eruption, and then these masses freeze. This hypothesis is supported by icebergs that can be seen on the surface of the satellite.
In general, the surface of Europa does not have elevations higher than 100 m, so it is considered one of the smoothest bodies in the solar system. Europa's thin atmosphere contains mainly molecular oxygen. Apparently, this is due to the decomposition of ice into hydrogen and oxygen under the influence of solar radiation, as well as other hard radiation. As a result, molecular hydrogen quickly evaporates from Europa's surface due to its lightness and weak gravity on Europa.
Ganymede
The satellite got its name in honor of the handsome youth whom Zeus brought to Olympus and made the cupbearer at the feasts of the gods. Ganymede is the largest satellite in the solar system. Its diameter is 5268 km. If its orbit was not around Jupiter, but around the Sun, it would be considered a planet. The distance between Ganymede and Jupiter is about 1070 million km. It is the only satellite in the solar system that has its own magnetosphere.
About 60% of the satellite is occupied by strange bands of ice, which were the result of active geological processes that took place 3.5 billion years ago, and 40% is an ancient powerful ice crust covered with many craters.
Possible internal structure of Ganymede
The core and silicate mantle of Ganymede generate heat that makes the underground ocean possible. According to scientists, it is below the surface at a depth of 200 km, while in Europe, a large ocean is located closer to the surface.
But the thin layer of the atmosphere of Ganymede, consisting of oxygen, is similar to the atmosphere found in Europa. Compared to other moons of Jupiter, flat craters on Ganymede practically do not form a hill and do not have a depression in the center, as do craters on the Moon. This seems to be due to the slow, gradual movement of the soft ice surface.
Callisto
Satellite Callisto got its name in honor of another beloved of Zeus. With a diameter of 4820 km, it is the third largest satellite in the solar system, and it is about 99% of the diameter of Mercury, while the mass of the satellite is three times less than that of this planet.
The age of Callisto, like that of Jupiter itself and other Galilean satellites, is also about 4.5 billion years old, but its distance to Jupiter is much larger than other satellites, almost 1.9 million kilometers. Thanks to this, the rigid radiation field of the gas giant does not affect it.
Callisto's surface is one of the oldest surfaces in the solar system - about 4 billion years old. All of it is covered with craters, so over time, each meteorite necessarily fell into an existing crater. Callisto lacks violent tectonic activity, its surface does not heat up after formation, so it has retained its ancient appearance.
According to many scientists, Callisto is covered with a thick layer of ice, under which is the ocean, and in the center of the satellite contains rocks and iron. Its thin atmosphere is made up of carbon dioxide.
The Valhalla crater with a total diameter of about 3800 km deserves special attention on Callisto. It consists of a bright central region with a diameter of 360 km, surrounded by ridge concentric rings with a radius of up to 1900 kilometers. This whole picture resembles circles on the water from a stone thrown into it, only in this case a large asteroid 10-20 km in size played the role of a “stone”. Valhalla is considered the largest formation in the solar system around an impact crater, although the crater itself is only 13th in size.
Valhalla - Impact Pool on the Callisto satellite
As already mentioned, Callisto is outside the hard radiation field of Jupiter, therefore it is considered as the most suitable object (after the Moon and Mars) for the construction of a space base. Ice can serve as a source of water, and from Callisto itself it will be convenient to explore another moon of Jupiter - Europa.
It will take 2 to 5 years to fly to Callisto. The first manned mission is planned to be sent no earlier than 2040, although the flight may begin later.
Callisto's internal structure model
Shown: ice crust, a possible water ocean and a core of rocks and ice.
Jupiter's inner moons
The inner moons of Jupiter are so named because of their orbits, which are very close to the planet and are located within the orbit of Io, which is the closest Galilean satellite to Jupiter. There are four inner satellites: Metis, Amalthea, Adrastea and Thebes.
Amalthea, 3D model
Jupiter's faint ring system is replenished and supported not only by inner moons, but also by small inner moons, which are still invisible. Jupiter's main ring is supported by Metis and Adrastea, while Amalthea and Thebes have to maintain their own weak outer rings.
Of all the inner satellites, Amalthea is of the greatest interest with its deep red surface. The fact is that this has no analogues in the solar system. There is a hypothesis that this color of the surface is explained by inclusions of minerals and sulfur-containing substances in the ice, but this does not clarify the reason for this color. It is more likely that the capture of this moon by Jupiter occurred from the outside, as is regularly the case with comets.
Jupiter's outer moons
The outer group consists of small satellites with diameters ranging from 1 to 170 km, which move in elongated orbits with a strong inclination to the equator of Jupiter. To date, 59 such external satellites are known. Unlike the inner satellites, which move in their own orbits in the direction of Jupiter's rotation, most of the outer satellites move in their orbits in the opposite direction.
The orbits of Jupiter's moons
Since some small satellites have nearly identical orbits, it is assumed that they are the remnants of larger satellites destroyed by Jupiter's gravity. In pictures taken from spacecraft flying by, they look like shapeless lumps. Obviously, Jupiter's gravitational field captured some of them during their free flight in space.
Jupiter's rings
Along with satellites, Jupiter also has its own system, like other gas giants in the solar system: Saturn, Uranus and Neptune. The rings of Saturn, discovered by Galileo in 1610, look much more spectacular and more noticeable, since they consist of shiny ice, while in Jupiter it is just an insignificant dusty structure. This explains their late discovery, when a spacecraft first reached the Jupiter system in the 1970s.
Galileo's image of the main ring in forward-scattered light
Jupiter's ring system is formed by four main components:
A halo is a thick torus of particles that looks like a donut or a disc with a hole;
The main ring is very thin and quite bright;
Two outer rings, wide but weak, called "spider rings".
The Halo and the Main Ring are composed mainly of dust from Metis, Adrastea, and probably several other smaller satellites. The halo is approximately 20 to 40 thousand km wide, although its main component is no further than a few hundred kilometers from the plane of the ring. The halo shape, according to a popular hypothesis, is due to the effect of electromagnetic forces inside the Jupiter magnetosphere on dust particles in the ring.
Spiderweb rings are very thin and transparent, like a spider's web, they were named after the material of the satellites of Jupiter, Amalthea and Thebes that form them. The outer edges of the Main Ring are outlined by the satellites Adrastea and Metis.
Jupiter's rings and inner moons
