The most shapeless satellite. Ganymede is Jupiter's largest moon. Brightest comet
The largest planet in the solar system
The largest planet in the solar system and the most massive of them is Jupiter. Its equatorial diameter is 143884 km, which is 11.209 times the diameter of the Earth and is 0.103 times the diameter of the Sun. In volume it is equivalent to 1319 volumes of the Earth. The mass of Jupiter is 318 times the mass of the Earth, and 2.5 times the mass of all other planets combined. In order to form a mass equal to the mass of the Sun, 1047 planets such as Jupiter would be required.
The equatorial diameter of the next largest planet, Saturn, is 0.84 that of Jupiter, and its mass is 0.30 that of the largest planet. Jupiter and Saturn were able to reach such large sizes because they were formed in the early period of the solar system in a place where large amounts of gas from the protoplanetary nebula could be collected.
Planet with the most moons
Over the past decade, many new moons of the giant planets - Jupiter, Saturn, Uranus and Neptune - have been discovered. On October 1, 2004, Jupiter had the largest number of moons - 63, followed by 33 moons, then 26 and 13. It is likely that all four planets have small moons that have not yet been discovered. The origin of planetary moons is not entirely clear. However, it seems likely that the large moons of these giant gas planets formed alongside and at the same time as their parent planets, and that the small outer moons are asteroids captured later.
Hottest planet
Venus has a surface temperature of 460 to 480 °C, making it the hottest planet in the solar system. The high temperature of the Venusian surface is due to the presence of a dense atmosphere consisting of carbon dioxide. The atmosphere acts as an insulating blanket. The average surface temperature is 500 degrees higher than what it would be in the absence of an atmosphere. Solar radiation penetrates the clouds of Venus, and due to the presence of carbon dioxide in the atmosphere, a phenomenon known as the greenhouse effect occurs.
In the early history of the solar system, when the Sun was not as bright as it is now, Venus was cooler and likely had oceans of liquid water. The water gradually evaporated, contributing to the greenhouse effect, but in about a million years all of it dissipated into outer space. As the temperature increased, more and more carbon dioxide was released from the rocks on the surface of the planet, which led to the rapid development of the greenhouse effect and to the currently observed overheating of Venus.
The brightest planet in the solar system
The brightest planet in the solar system is . Its maximum magnitude is -4.4. Venus is closest to Earth and, in addition, effectively reflects sunlight, since the surface of the planet is covered with clouds. The top layers of the clouds of Venus reflect 76% of the sunlight falling on them.
Venus appears brightest when it is in its crescent phase to an observer on Earth. Venus's orbit lies closer to the Sun than the Earth's, so Venus's disk is only fully illuminated when it is on the opposite side of the Sun. At this time, the distance to Venus is greatest, and its apparent diameter is smallest.
The smallest planet in the solar system
The smallest planet in the solar system is Pluto. Its diameter is only 2400 km. The rotation period is 6.39 days. The mass is 500 times less than the earth's. Has a satellite, Charon, discovered by J. Christie and R. Harrington in 1978. In 2006, Pluto was recognized as a dwarf planet.
Windiest planet in the solar system
The highest wind speeds in the solar system were recorded on Neptune in the equatorial region of the planet. Large-scale atmospheric formations move here from east to west at a speed of about 325 m/sec relative to the planet's core, and smaller ones move almost twice as fast. This means that the flow speeds near Neptune's equator are approaching supersonic.
The speed of sound in Neptune's atmosphere is approximately 600 m/sec. Strong winds are observed on all giant planets, but it is not clear why the fastest atmospheric movement is observed on Neptune. This may be due to the influence of Neptune's internal heat sources. The second among the “windiest” planets is Saturn, where maximum wind speeds are approximately half that of Neptune.
The coldest place in the solar system
The lowest temperature ever recorded on the surface of a body in the solar system is that of one of Neptune's moons, Triton. According to measurements made by Voyager 2, this temperature turned out to be –235 °C, which is only 38 °C above absolute zero. Pluto's surface temperature is almost certainly close to these values, but so far we only have estimates made from the Earth's surface.
According to these estimates, the bright regions of Pluto are about -233 °C, while the darker regions are about 20 °C warmer. Pluto and Triton appear very similar to each other: the degree of their similarity is much greater than that of any other pair of bodies in the solar system. The surface temperature of planets or moons depends on several factors: how great the distance from the Sun is, whether there is an internal heat source, what is the influence of the atmosphere. Both Triton and Pluto receive very little heat from the Sun, have no internal heat source, and are greatly cooled by the evaporation of ice from their surfaces.
Biggest moon
The largest moon in the solar system is Jupiter's satellite Ganymede, whose diameter is 5262 km. The largest moon of Saturn, Titan is the second largest (diameter is 5150 km), although Titan was previously thought to be larger than Ganymede. In third place is Jupiter's satellite, Callisto, adjacent to Ganymede. Ganymede and Callisto are larger than the planet Mercury (which has a diameter of 4878 km). Ganymede owes its status as the “largest moon” to the thick mantle of ice that covers its rocky interior.
The solid cores of Ganymede and Callisto are likely similar in size to Jupiter's two small inner Galilean moons, Io (3,630 km) and Europa (3,138 km). However, due to their proximity to Jupiter, they receive more heat, so Io has no icy mantle at all, while Europa has only a thin crust of ice, possibly with a layer of melted water underneath the ice. In contrast, Ganymede is half ice and half solid rock.
The smallest moon
The smallest moon whose dimensions are precisely known is the satellite of Mars. Its shape is close to an ellipsoid with axes 15x12x11 km. A possible rival to Deimos is the moon of Jupiter, whose diameter is estimated at about 10 km. The sizes of other small moons orbiting the outer planets are difficult to determine precisely because they can only be observed as point objects. Estimates of their sizes depend on what value is taken for the reflectivity of their surface.
The diameters of some of the recently discovered moons of Jupiter and Saturn are estimated to be only a few kilometers. Deimos, like another moon of Mars, and most of the new moons of the giant planets are believed to be asteroids captured by planets. Both moons of Mars have very dark surfaces, reflecting only a few percent of the light that falls on them. These moons are similar to the asteroids typically found in the outer asteroid belt and in the Trojan group of asteroids associated with Jupiter. It is possible that Leda is an asteroid captured by Jupiter and found itself in orbit around it.
Tallest volcano in the solar system
The tallest volcanoes in the solar system are the shield volcanoes on Mars. Mount Olympus has the highest height. Its peak rises 25 km above the level of the surrounding plateau, and the diameter of the base is almost 550 km. For comparison: the Hawaiian Islands on Earth rise above the seabed by only 10 km. Shield volcanoes grow in height gradually, as a result of repeated eruptions from the same vent. Shield volcanoes are much larger on Mars than on Earth for several reasons.
Although these volcanoes are apparently no longer active, they likely formed earlier and were active much longer than any volcanoes on Earth. At the same time, hot volcanic spots on Earth changed their location over time due to the gradual movement of continental plates, so that there was not enough time to “build” a very tall volcano in each individual case. In addition, low gravity allows erupted material to form much taller structures on Mars that do not collapse under their own weight.
Most Observed Comet
The periodic comet 2P/Encke has recorded the most returns to Earth. Since it never moves further than 4 astronomical units from the Sun, barely leaving the asteroid belt, with modern observation methods it can be observed continuously. Comet 2P/Encke has an unusual orbit—its period is only 3.3 years, much shorter than any other periodic comet. Independent “discoveries” of this comet were made first by Pierre Mechain (in 1786) and Caroline Herschel (in 1795), and then (in 1805 and 1818) by Jean Louis Pons. But already in 1819, Johann Encke realized that all these observations belonged to the same comet, and calculated its orbit. From then until 2005, 59 passages of the comet through perihelion were recorded. The number of appearances of this comet in the sky can, for example, be compared with the 30 known returns of Halley's Comet since 239 BC. until 1986
Comet observed for the longest period of time
Halley's Comet (1P) in 1986 Sightings of Halley's Comet, officially known as Comet 1P/Halley, have been traced back to 239 BC. e. No other periodic comet has a historical record that can compare with Halley's Comet. Halley's Comet is unique: it has been observed 30 times over more than two thousand years. This is because this comet is much larger and more active than other periodic comets.
The comet is named for Edmund Halley, who in 1705 realized the connection between several previous appearances of the comet and predicted its return in 1758-59. In 1986, the Giotto spacecraft was able to image the nucleus of Halley's comet from a distance of only 10 thousand kilometers. It turned out that its core is 15 km long and 8 km wide. The coma and tail of this most famous comet are formed when the nucleus is heated by the Sun. And emissions of gas and dust break through the dark shell covering the icy core.
Brightest comet
Based on the surviving records, it is impossible to judge which of the comets observed in the past was the brightest. Since bright comets are very extended celestial objects, it is almost impossible to accurately determine their brightness. The impressions an observer receives from a particular comet are very subjective; they depend on the length of the tail and how dark the sky was at the time of observation.
The brightest comets of the 20th century include the so-called “Great Comet of Daylight” (1910), Comet Halley (when it appeared in the same 1910), comets Schellerup-Maristany (1927), Bennett (1970) , Vesta (1976), Heil-Bopp (1997). The brightest comets of the 19th century are probably the “Great Comets” of 1811, 1861 and 1882. Previously, very bright comets were recorded in 1743, 1577, 1471 and 1402. The closest (and brightest) appearance of Halley's Comet was noted in 837.
Closest comet approach to Earth
Among the recorded approaches of comets, Comet Lexel came closest to the Earth in 1770. The shortest distance to the Earth was reached on July 1, 1770 and amounted to 0.015 astronomical units (i.e. 2.244 million kilometers). This is six times the distance to the Moon. When the comet was closest, the apparent size of its coma was almost five times the diameter of the full Moon.
The comet was discovered by Charles Messier on June 14, 1770, but received its name from Anders Johann (Andrei Ivanovich) Leksel, who determined the comet's orbit and the results of his calculations in 1772 and 1779. He discovered that in 1767 the comet came close to Jupiter and, under its gravitational influence, moved into an orbit that passed close to the Earth. However, during the next, even closer approach to Jupiter, the disturbance in the trajectory of Comet Lexel turned out to be so great that it was no longer observed from Earth.
Largest asteroid
Sedna (2003 VB 12) is the largest and most distant asteroid in the Solar System. It is slightly smaller than Pluto, with an estimated diameter of 1,700 km.
Sedna's orbit is very elongated; the asteroid is currently located at a distance of about 90 AU. from the sun. Sedna is a potential member of the Oort cloud.
Of all the satellites of the solar system, several of the most unusual can be distinguished. They all have some interesting features, which will be discussed below.
Ganymede is the largest satellite
Jupiter's moon Ganymede itself is very similar to the Moon, but it is much larger and is the largest satellite of the entire solar system. Another feature is the presence of magnetic poles. Ganymede is slightly larger than Mercury and slightly smaller than Mars; it could be mistaken for a planet if it also revolved around the Sun.
Ganymede
Miranda is not the most attractive companion
The satellites of Uranus are not very presentable. A satellite called Miranda stands out from all these satellites. Its name is beautiful, but its appearance is not very good. However, a closer look at Miranda's surface reveals the most diverse landscape in the solar system: giant ridges alternate with deep plains, and some canyons are 12 times deeper than the famous Grand Canyon!
Miranda
Callisto - crater champion
Jupiter's satellite Calisto immediately appears to be a dead planet that has no signs of life. A lot of meteorites fell on this satellite and, accordingly, they all left behind traces, which are now presented in the form of craters on the satellite. This is the main distinguishing feature of Kalisto. It has the largest number of craters of all the planets and satellites of the Solar System.
Callisto (bottom and left), Jupiter (top and right) and Europa (below and left of the Great Red Spot)
Dactyl - asteroid satellite
Dactyl is a satellite whose main distinguishing feature is that it is the smallest of all the satellites in the solar system. It is only 1.6 km long, but it orbits the asteroid. Dactyl is the companion of Ida. According to ancient Greek myth, Ida was the name of a mountain in which tiny creatures lived - dactyls.
Asteroid Ida and its satellite Dactyl
Epimetheus and Janus - an eternal race
In the distant past, the two satellites of Saturn were one, but after the split they began to move almost in the same orbit, changing places every four years and miraculously avoiding collision.
Epimetheus and Janus
Enceladus the Ringbearer
Enceladus is one of the largest moons of Saturn. Almost all of the sunlight falls and reflects on it, as a result of which it is considered the most reflective object in the solar system. Enceladus has geysers that emit water vapor and dust into outer space. Scientists believe that it was due to the volcanic activity of its satellite that Saturn acquired an E ring, through which Enceladus’ orbit will lie.
E Ring and Enceladus
Triton - a satellite with unique volcanoes
Triton is Neptune's largest satellite. This satellite differs from others in that it revolves around the planet in the direction opposite to its rotation around the Sun. Triton has a large number of volcanoes that emit non-lava, water and ammonia, which freeze instantly afterwards.
Triton
Europe - ocean satellite
Europa is a satellite of Jupiter that has the smoothest surface. This feature is due to the fact that Europe is all covered with ocean, and on its surface there is a thin layer of ice. Under the ice there is a huge amount of liquid - several times more than on Earth. Some researchers who study this satellite have come to the conclusion that there may be life in Europa's ocean.
Europe
Io is a volcanic hell
There is constant volcanic activity on Jupiter's moon Io. This is due to the very nature of the planet Jupiter, as a result of which the bowels of the satellite are subject to heating. There are more than 400 volcanoes on the surface, and volcano formation occurs continuously; they can be easily noticed when flying past. But for the same reason, craters are practically invisible on the surface of Io, since they are filled with lava that erupts from volcanoes.
Titan is the best candidate for colonization
Saturn's moon Titan is the most unpredictable and unique satellite. It has long been proven that it has a denser atmosphere than on Earth. Which contains nitrogen, methane and other gases. For a long time it was unknown what was hidden under these thick clouds of the satellite, and only after the device took pictures, it became clear that there were rivers and lakes of a metonic and titanium nature. It is assumed that Titan also has underground reservoirs, which, coupled with low gravity, makes it a better candidate for colonization by earthlings.
Titan's upper atmosphere and Saturn's south pole
There are good reasons to believe that humans will not only be able to survive on Jupiter's moon Europa, but will also find life already existing there. Europa is covered with a thick ice crust, but many scientists are inclined to believe that underneath there is a real ocean of liquid water. Additionally, Europa's solid inner core adds to the chances of having the right environment to support life, be it ordinary microbes or perhaps even more complex organisms.
It is definitely worth studying Europe for the presence of conditions for the existence of life and life itself. After all, this will greatly increase the chances of possible colonization of this world. NASA wants to test whether Europa's water has some connection to the planet's core and whether this reaction produces heat and hydrogen, like we do on Earth. In turn, studying the various oxidizing agents that may be present in the planet's icy crust will indicate the level of oxygen produced, as well as how much of it is located closer to the ocean floor.
There are prerequisites to believe that NASA will closely study Europe and attempt to fly there by 2025. It is then that we will find out whether the theories associated with this icy satellite are true. In situ studies could also reveal the presence of active volcanoes beneath the icy surface, which in turn would also increase the chances of life on this moon. Indeed, thanks to these volcanoes, essential minerals can accumulate in the ocean.
Titanium
Even though Titan, one of Saturn's moons, lies on the outer edge of the solar system, this world is one of the most interesting places for humanity and perhaps one of the candidates for future colonization.
Of course, breathing here will require the use of special equipment (the atmosphere is unsuitable for us), but there is no need to use special pressure suits here. However, of course, you will still have to wear special protective clothing, since the temperature here is very low, often dropping to -179 degrees Celsius. The gravity on this satellite is slightly lower than the level of gravity on the Moon, which means walking on the surface will be relatively easy.
However, you will have to seriously think about how to grow crops and take care of issues of artificial lighting, since only 1/300 to 1/1000 of the Earth’s level of sunlight falls on Titan. Dense clouds are to blame, but they nevertheless protect the satellite from excessive levels of radiation.
There is no water on Titan, but there are entire oceans of liquid methane. In this regard, some scientists continue to debate whether life could have formed under such conditions. Regardless, there is a lot to explore on Titan. There are countless methane rivers and lakes and large mountains. Plus, the views must be absolutely stunning. Due to Titan's relative proximity to Saturn, the planet in the satellite's sky (depending on cloudiness) occupies up to one third of the sky.
Miranda
Although Uranus's largest moon is Titania, Miranda, the smallest of the planet's five moons, is most suitable for colonization. Miranda has several very deep canyons, deeper than the Grand Canyon on Earth. These locations could be ideal for landing and establishing a base that would be protected from the harsh external environment and especially from the radioactive particles produced by the magnetosphere of Uranus itself.
There is ice on Miranda. Astronomers and researchers estimate that it makes up about half the composition of this satellite. Like Europa, there is a possibility of water on the satellite, which is hidden under the ice cap. We don't know for sure, and we won't know until we get closer to Miranda. If there is still water on Miranda, then this would indicate serious geological activity on the satellite, since it is too far from the Sun and sunlight is not able to maintain water in liquid form here. Geological activity, in turn, would explain all this. While this is just a theory (and most likely unlikely), Miranda's close proximity to Uranus and its tidal forces may be causing this very geological activity.
Whether there is liquid water here or not, if we establish a colony on Miranda, the very low gravity of the satellite will allow us to descend into the deep canyons without fatal consequences. In general, there will also be something to do and explore here.
Enceladus
According to some researchers, Enceladus, one of Saturn's moons, not only could be an excellent place to colonize and observe the planet, but is also one of the most likely places to already support life.
Enceladus is covered in ice, but observations from space probes have shown geological activity on the moon and, in particular, geysers erupting from its surface. The Cassini spacecraft collected samples and determined the presence of liquid water, nitrogen and organic carbon. These elements, as well as the energy source that released them into space, are the important “building blocks of life.” So the next step for scientists will be to detect signs of more complex elements and perhaps organisms that may be lurking beneath Enceladus's icy surface.
The researchers believe that the best place to establish a colony would be in the areas near which these geysers have been spotted - huge cracks on the surface of the south pole ice cap. Quite unusual thermal activity has been observed here, equivalent to the operation of approximately 20 coal-fired power plants. In other words, there is a suitable source of heat for future colonists.
Enceladus has many craters and fissures just waiting to be explored. Unfortunately, the atmosphere of the satellite is very thin, and low gravity can create some problems in the development of this world.
Charon
NASA's New Horizons spacecraft returned stunning images of the dwarf planet and its largest moon Charon after its encounter with Pluto. These images have caused heated debate in the scientific community, which is now trying to determine whether this satellite is geologically active or not. It turned out that the surface of Charon (as well as Pluto) is much younger than previously thought.
Although there are cracks in Charon's surface, the moon appears to be quite effective at avoiding asteroid impacts as it has very few impact craters. The cracks and faults themselves are very similar to those left by the flow of hot lava. The same cracks have been found on the Moon and are an ideal place to establish a colony.
It is believed that Charon has a very thin atmosphere, which may also be an indicator of geological activity.
Mimas
Mimas is often called the "Death Star". It is possible that an ocean may be hidden under the ice cap of this satellite. And despite this moon's overall ominous appearance, it may actually be suitable for supporting life. Observations by the Cassini space probe showed that Mimas wobbles slightly in its orbit, which could indicate geological activity beneath its surface.
And although scientists are very careful in their assumptions, no other traces that would indicate the geological activity of the satellite were found. If an ocean is discovered on Mimas, then this moon should be one of the first to be considered as the most suitable candidate for establishing a colony here. Rough calculations indicate that the ocean may be hidden at a depth of about 24-29 kilometers below the surface.
If the unusual orbital behavior has nothing to do with the presence of liquid water under the surface of this satellite, then, most likely, it is all to do with its deformed core. And the strong gravitational pool of Saturn's rings is to blame for this. Be that as it may, the most obvious and most reliable way to find out what is happening here is to land on the surface and take the necessary measurements.
Triton
Images and data from the Voyager 2 spacecraft in August 1989 showed that the surface of Neptune's largest moon, Triton, is composed of rocks and nitrogen ice. In addition, the data hinted that there may be liquid water beneath the moon's surface.
Although Triton has an atmosphere, it is so thin that it is of no use on the surface of the satellite. Being here without a particularly protected spacesuit is like death. Triton's average surface temperature is -235 degrees Celsius, making it the coldest cosmic object in the known universe.
Nevertheless, Triton is very interesting for scientists. And one day they would like to get there, establish a base and carry out all the necessary scientific observations and research:
“Some areas of Triton's surface reflect light as if they were made of something hard and smooth, like metal. These areas are believed to contain dust, nitrogen gas and possibly water that seeps through the surface and freezes instantly as a result of the incredibly low temperatures."
In addition, scientists estimate that Triton formed around the same time and from the same material as Neptune, which is quite strange given the size of the satellite. It appears to have formed somewhere else in the solar system and was then pulled in by Neptune's gravity. Moreover, the satellite rotates in the direction opposite to its planet. Triton is the only satellite of the solar system that has this feature.
Ganymede
Jupiter's largest moon, Ganymede, as well as other space objects in our solar system, have been suspected of the presence of water beneath the surface. Compared to other ice-covered moons, Ganymede's surface is considered relatively thin and easy to drill into.
In addition, Ganymede is the only satellite in the Solar System that has its own magnetic field. Thanks to this, northern lights can be observed very often over its polar regions. In addition, there are suspicions that a liquid ocean may be hiding under the surface of Ganymede. The satellite has a rarefied atmosphere, which contains oxygen. And although it is extremely small to support life as we know it, the satellite has the potential for terraforming.
In 2012, it planned a space mission to Ganymede, as well as two other moons of Jupiter, Callisto and Europa. The launch is planned for 2022. It will be possible to get to Ganymede 10 years later. Although all three moons are of great interest to scientists, Ganymede is believed to contain the most interesting features and is potentially suitable for colonization.
Callisto
Roughly the size of the planet Mercury, Jupiter's second-largest moon is Callisto, another moon that has been suggested to contain water beneath its icy surface. In addition, the satellite is considered a suitable candidate for future colonization.
Callisto's surface mainly consists of craters and ice fields. The satellite's atmosphere is a mixture of carbon dioxide. Scientists are already suggesting that the very thin atmosphere of the satellite is replenished with carbon dioxide escaping from under the surface. Previously obtained data indicated the possibility of the presence of oxygen in the atmosphere, but further observations did not confirm this information.
Since Callisto is at a safe distance from Jupiter, radiation from the planet will be relatively low. And the lack of geological activity makes the satellite's environment more stable for potential colonists. In other words, it is possible to build a colony here on the surface, and not under it, as in many cases with other satellites.
Moon
So we have come to the first potential colony that humanity will establish outside its planet. We are, of course, talking about our Moon. Many scientists are inclined to believe that a colony on our natural satellite will appear in the next decade, and soon after that the Moon will become the starting point for more distant space missions.
Chris McKay, a NASA astrobiologist, is among those who believe the Moon is the most likely site for the first human space colony. McKay is confident that further exploration of the Moon with a space mission after Apollo 17 did not continue solely due to considerations of the cost of this program. However, current technologies developed for use on Earth can also be very cost-effective for use in space and will significantly reduce the cost of both the launches themselves and construction on the lunar surface.
Despite the fact that NASA's biggest mission right now is landing a man on Mars, McKay is confident that this plan will not be realized until the first lunar base appears on the Moon, which will become the starting point for further missions to the Red Planet. Not only many states, but also many private companies are showing interest in the colonization of the Moon and are even preparing corresponding plans.
Some of these moons still remain a mystery to astronomers, because not everywhere has a human foot set foot before, but somewhere the existence of living organisms is quite possible! But what we do know for sure is at least their size. This list will introduce you to the 10 largest planetary moons in our solar system.
10. Oberon, satellite of Uranus (average diameter - 1523 kilometers)
Oberon, also known as Uranus IV, is the outermost satellite from the center of Uranus, the second largest of the other satellites of this planet, and the ninth largest of all known satellites of our solar system. Discovered in 1787 by explorer William Herschel, Oberon is named after the mythical king of elves and fairies mentioned in Shakespeare's A Midsummer Night's Dream. Oberon's orbit lies partially outside the magnetosphere of Uranus.
9. Rhea, satellite of Saturn (average diameter - 1529 kilometers)
Rhea is the second largest satellite of Saturn and the ninth largest satellite in the entire Solar System. At the same time, it is the second smallest cosmic body in our solar system, second only to the asteroid and the dwarf planet Ceres in this rating. Rhea received this status for confirmed data that she has hydrostatic equilibrium. Discovered in 1672 by Giovanni Cassini.
8. Titania, satellite of Uranus (average diameter - 1578 kilometers)
It is the largest moon of Uranus and the eighth largest in the solar system. Discovered in 1787 by William Herschel, Titania was named after the fairy goddess from Shakespeare's A Midsummer Night's Dream. Titania's orbit does not extend beyond the magnetosphere of Uranus.
7. Triton, satellite of Neptune (average diameter - 2707 kilometers)
Triton is the largest satellite of the planet Neptune, discovered on October 10, 1846 by the English astronomer William Lassell. In our solar system, it is the only large moon with a retrograde orbit. Triton moves in the opposite direction to its planet's rotation. With its 2,707 kilometers in diameter, Triton is considered the seventh largest moon in the solar system. There was a time when Triton was considered a dwarf planet from the Kuiper belt due to its retrograde and compositional properties similar to Pluto.
6. Europa, a satellite of Jupiter (average diameter - 3122 kilometers)
It is the smallest of the Galilean moons orbiting Jupiter and the sixth closest to its planet. It is also the sixth largest satellite in the Solar System. Galileo Galilei discovered Europa in 1610 and named this celestial body after the legendary mother of the Cretan King Minos and lover of Zeus.
5. Moon, satellite of the Earth (average diameter - 3475 kilometers)
It is believed that our Moon formed 4.5 billion years ago, shortly after the formation of the Earth itself. There are several hypotheses about its origin. The most common among them says that the Moon was formed from fragments after the collision of the Earth with the cosmic body Theia, comparable in size to Mars.
4. Io, a satellite of Jupiter (average diameter - 3643 kilometers)
Io is the most geologically active celestial object in our solar system, earning that title with at least 400 active volcanoes. The reason for this extreme activity is the heating of the satellite's interior due to tidal friction caused by the gravitational influence of Jupiter and the other Galilean moons (Europa, Ganymede and Callisto).
3. Callisto, a satellite of Jupiter (average diameter - 4821 kilometers)
Galileo Galilei discovered Callisto, as well as several other moons of Jupiter, in 1610. Possessing impressive dimensions, this satellite makes up 99% of the diameter of Mercury, but only a third of its mass. Callisto is the fourth Galilean satellite of Jupiter in terms of distance from the center of the planet, with an orbital radius of 1,883,000 kilometers.
2. Titan, satellite of Saturn (average diameter - 5150 kilometers)
This is the sixth ellipsoidal satellite of Saturn. Very often it is called a planet-like satellite, because the diameter of Titan is 50% larger than the diameter of our Moon. In addition, it is 80% heavier than our Earth's satellite.
1. Ganymede, a satellite of Jupiter (average diameter - 5262 kilometers)
Ganymede is composed equally of silicate rocks and frozen water. It is a fully differentiated celestial body, rich in iron, with a liquid core and an outer ocean that may contain more water than the sum of all of the Earth's oceans. The surface of Ganymede has two types of relief. The dark regions of the satellite are littered with craters from asteroid impacts that supposedly occurred 4 billion years ago. This landform covers approximately a third of the satellite.