Definition of planets: First, it must surroundfixed starA moving celestial body;Second, the mass is large enough to makecelestial bodiesIt is round and spherical;Third, there should be no other objects near this orbit (clear other objects on its orbit).According to this division, there are only eight planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.[2]
Too high temperature difference, lack of atmosphere, and too strong solar radiation
Messenger
nothing
Venus
zero point eight two
six
zero point eight five six
six
five point two six
three
224.7 days
243 days
eight
four hundred and sixty-four
one
ninety-three
The air pressure is extremely high and the temperature is too high
Venera 7
nothing
earth
one
five
one
five
five point five two
one
1 year
23 hours and 56 minutes
five
fifteen
three
one
Perfect for biological survival
Permanent residence
one
Mars
zero point one one
seven
zero point one five zero
seven
three point nine six
four
1.9 years
24 hours and 37 minutes
six
27 (summer), - 133 (winter)
four
Extremely small (less than 1% of the earth's atmospheric pressure)
The atmosphere is too thin and the temperature is low, but it can be improved by humans
Tianwen No.1
two
huge
that 's ok
Star
Jupiter
three hundred and seventeen point nine four
one
one thousand three hundred and thirteen
one
one point three three
six
11.8 years
9 hours and 50 minutes
one
-120
five
200Kpa
Gas planets can't support life
The following are all gaseous planets, unable to land
sixty-four
Saturn
ninety-five point one eight
two
seven hundred and forty-five
two
zero point seven zero
eight
29.5 years
10 hours and 14 minutes
two
-180
six
one
two hundred
frozen
Gaseous
that 's ok
Star
Uranus
fourteen point six three
four
sixty-five point two zero zero
three
one point two four
seven
84.0 years
17 hours, 14 minutes and 24 seconds
four
-216~-224
eight
zero point one
twenty-seven
Neptune
seventeen point two two
three
fifty-seven point one zero zero
four
one point six six
five
164.8
15 hours, 57 minutes and 59 seconds
three
-214
seven
-
fourteen
Mercury
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English name: Mercury
MercuryClosest to the sun[3], which is the smallest planet in size and mass in the solar system.It often appears with the sun at the same time. In ancient China, it was called "Chenxing".Mercury is smaller than two moons in diameter——Ganymedeandtitan。
Orbit of revolution: 57910000km (0.38 km) from the sunAstronomical unit）
Name Source
In ancient timesRoman mythIn China, Mercury is the god of commerce, travel and theftMYTHOSInHermesThe god who preaches for the gods may get this name because Mercury moves fast in the air.
Detection history
planets
Discovery:As early as 3000 BCSumerian eraPeople discovered Mercury,ancient GreekPeople gave it two names: when it first appeared in the morning, it was calledApollo, when it flashes in the night sky, it is calledHermes。However, ancient Greek astronomers knew that these two names actually referred to the same star. Heraclitus even believed thatMercuryVenus does not orbit the earth, but orbits the sun.
visit:Now onlyMariner 10 The probe visited Mercury three times in 1973 and 1974.It surveyed only 45% of Mercury's surface (and unfortunately, becauseMercuryToo closesunlight, so thathubble space telescope It cannot be safely filmed).
Before 1962, people had always believed that the time of one revolution of Mercury was the same as that of one revolution, so that the side facing the sun was constant.This is related toMoonIt is very similar to always face the earth with the same half face.But in 1965, throughDoppler radar Our observation found that this theory is wrong.We have learned that Mercury rotates three times at the same time when it rotates two times. Only Venus is the only known celestial body in the solar system whose co motion ratio of revolution period and rotation period is less than 1:1. Mercury is not.
Because of the above situation and the extreme deviation of Mercury's orbit from the perfect circleObserverSeeing a very strange scene, the observer at some longitude will see that when the sun riseszenithMoving slowly will gradually increase the size significantly.The sun will stop at the zenith, go through a short backward process, stop again, and then continue its journey tohorizonThe journey, while significantly shrinking.During this period, the stars will row across the sky three times faster.Observers at other places on the surface of Mercury will see different, but the same is unusualCelestial motion。
Perihelion orbit
Mercury's orbit deviates from the perfect circle to a great extent. It is in orbitPerihelionThe slowness around the sunprecession of the equinoxesPhenomenon, known as "Mercury perihelion orbitPrecession”。(Precession:Precession of earth axiscauseVernal equinoxIt slowly runs westward at a speed of 0.2 ″ every year, and runs for one week in about 25800 years, making the regression year shorter than the stellar year.Sum of diurnal precessionPlanetary precessionTwo, the latter is caused by planetary gravityEcliptic surfaceCaused by changes.)In the 19th century, astronomers observed the orbit radius of Mercury very carefully, but they were unable to useNewtonian mechanicsMake appropriate explanation for this.Exists between the actual observed value andForecast valueThe slight difference between them is a minor problem (one seventh of a degree difference per thousand years) but has puzzled astronomers for decades.Some people think that there is another planet (sometimes called Vulcan“Zhu Rongxing”）, to explain the difference, the final answer is quiteDramatic：EinsteinOfGeneral relativity。In the early days when people accepted this theory, the correct prediction of Mercury's movement was a very important factor.(Mercury due to solargravitational fieldAnd revolve around it, while the sunforce fieldIt is extremely huge. According to the general theory of relativity, mass produces gravitational field, and gravitational field can also be regarded as mass, so the giant gravitational field can be regarded as mass, producing small gravitational field, causing its orbital deviation.be similar toelectromagnetic waveThe variation of magnetic field generates electric field, and the variation of electric field generates magnetic field, which is transmitted far awayTranslation and annotation）
Temperature difference
MercuryTemperature differenceIs the largest in the entire solar system, with a temperature variation range of 90Kelvin(about - 183 ℃) to 700 Kelvin (about 427 ℃).In contrast, Venus is slightly warmer but more stable.
Atmospheric surface landform
In fact, Mercury's atmosphere is very thinsolar windBrought about by the destruction of atomic composition.Mercury's temperature is so high that these atoms quickly escape into space. Compared with the stable atmosphere of Earth and Venus, the atmosphere of Mercury is frequently supplemented and replaced.
Mercury's surface shows great urgencyInclined planeSome are hundreds of kilometers long and 3000 meters high.Some transverse positionsCraterThe appearance of other steep planes shows that they are formed by compression.It is estimated that the surface of Mercury has shrunk by about 0.1% (or about 1 km in the radius of the planet).
MercuryLargest onGeomorphic featuresOne is the Caloris Basin, which is about 1300 kilometers in diameter. It is thought to be similar to Maria, the largest basin on the moon.Like the basin of the moon, the Caloris basin was probably formed in the early collision of the solar system, which probably caused the strange terrain on the other side of the planet facing the basin at the same time.
In addition to being coveredMeteorite craterMercury also has relatively flat plains. Some may be the result of ancient volcanic activities, but others may be formed by meteoritesEjectaThe result of deposition.
Surprisingly, MercuryNorth PoleRadar scanning ofMariner 10 The survey area) shows that there are signs of ice in the well protected concealment of some meteorite craters.
Other properties
Mercury is similar to the moon in many ways. There are many craters on its surface and it is very old;Neither does itPlate movement。On the other hand, Mercury'sDensity ratioThe moon is much larger (5.43g/cm3 for Mercury and 3.34g/cm3 for the moon).Mercury is the second densest celestial body in the solar system after the Earth.In fact, the high density of the earth is partly due toUniversal gravitationCompression of;If not, the density of Mercury will be greater than that of the Earth, which indicates that the iron core of Mercury is relatively larger than that of the Earth, and it is likely to constitute most of the planet.Therefore, relatively speaking, Mercury has only one ring of thinsilicatemantleAnd the crust.
The huge iron core, with a radius of 1800 to 1900 kilometers, is the ruler of Mercury's interior.The silicate shell is only 500 to 600 kilometers thick, and at least part of the core is probably molten.
Usually throughBinocularsMercury can even be observed directly with the naked eye, but it is always very close to the sunTwilightHard to see in.Mike Harvey's planet search chart points out the position of Mercury in the sky at this time (and the position of other planets), and then more and more detailed customization will be made by the "Star Brilliant" astronomical program.
Venus
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English name: Venus
The sixth largest planet in the solar system, the planet with the highest temperature in the solar system, was called Taibai orHyperplatinum。It is sometimes the morning star. Dawn appears in the eastern sky and is called“Venus”；Sometimes it is the evening star, which appears in the western sky after dusk and is called "Chang Geng".
Venus“Aphrodite”；Babylonian: Ishtar) is the goddess of beauty and love. The reason why it is so named may be that for the ancient people, it is the brightest planet among the known planets.(There are also some objections that Venus is named because its surface is like that of a woman.)
Detection history
Discovery:Venus has been known since prehistory.Apart from the sun and moon, it is the brightest one.
Venus is a perihelion planet. If you observe it with a telescope from the Earth, you will find that it hasphaseChange.GalileoThe observation of this phenomenon is in favor ofCopernicusOf the solar systemHeliocentric theoryImportant evidence.
visit:The first aircraft to visit Venus was in 1962Mariner 2 。Later, it was successively used by other aircraft: Venus Pioneer,Soviet UnionDignity 7, Dignity 9 visits.
rotation
Venus's rotation is very unusual. On the one hand, it is very slow (Venus days are equivalent to 243earth dayOn the other hand, it rotates upside down.
Atmosphere and surface
Venusianatmospheric pressure93Standard atmospheric pressure(equivalent to the pressure of the earth's ocean at a depth of 1 km), the atmosphere is mostly composed ofcarbon dioxideThere are also several layers of clouds that are thousands of meters thick and composed of sulfuric acid.These clouds block our observation of the surface of Venus, making its surface completely different from the visual results.This dense atmosphere also produces a greenhouse effect, which makes the surface temperature of Venus rise by 400 degrees, more than 740K (enough to melt lead).Venus is naturally hotter than Mercury, although Venus is hotter than MercuryMercuryTwice as far from the sun.There is a strong wind at the top of the cloud layer, about 350 kilometers per hour, but the surface wind speed is very slow, less than several kilometers per hour.
Other properties
Venus is sometimes called the sister star of the earth, and they are very similar in some aspects:
Venus is slightly smaller than the Earth (95% of the Earth's diameter, 80% of the Earth's mass).
There are some ring-shaped mountain passes on the relatively young surface.
Their density is very similar to that of chemical composition.
Because of theseSimilaritiesSometimes it is thought that Venus may be very similar to the Earth under its thick clouds, and there may be life.Unfortunately, many in-depth studies on Venus show that Venus is fundamentally different from Earth in many aspects.
earth
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English: Earth
The Earth is the third planet from the sun and the fifth largest planet in the solar system. The Earth is the most dense planet in the solar system.The Earth, of course, can be observed without aircraft, but we didn't have a map of the entire planet until the twentieth century.Pictures taken from space should have reasonable importance;For example, they have greatly helpedMeteorological forecastAnd storm tracking forecast.
Basic parameters
Geophotograph
Semi major axis: 149597870km (such distance from the day is recorded as 1Astronomical unit, referred to as AU)
Equator radius: 6378.1km
Average track running speed: 29.79km/s
Track eccentricity: 0.0167
Rail inclination: 0 °
Quality: 5.9736 × 10twenty-fourkg
Equatorial gravity (Earth=1): 1.00
Escape speed (km/s): 11.2
Rotation period (day): 0.9973 (24h is defined as one day)
The earth is not from Greece orRoman mythThe name obtained in.The word Earth comes fromold EnglishandGermanic languages。There are certainly many other language names.In Roman mythology, the earth goddess is called Tellus - fertile land (Greek: Gaia, Mother Earth)
satellite
The earth's natural satellite isMoon, the only natural satellite on earth.The moon is the most obviousNatural satelliteExample of.In the solar system, all planets except Mercury and Venus have natural satellites.The moon is about 4.6 billion years old.The moon has a layered structure of shell, mantle and core.OutermostLunar shellThe average thickness is about 60-65km.Below the moon shell to a depth of 1000 kilometers isLunar mantleIt takes up most of the volume of the moon.Below the lunar mantle isMonthly checkThe temperature of the lunar core is about 1000 degrees, probablymeltStatus.The diameter of the moon is about 3474 kilometers, which is 3/11 of that of the earth.Its volume is only 1/49 of the earth, and its mass is about 735 billion tons, which is equivalent to 1/81 of the earth's mass. The gravity of the moon surface is about 1/6 of the earth's gravity.
Earth MoonInteractionThe rotation of the earth slows down by 2 milliseconds every century.
Mars
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English name: Mars
It is the fourth farthest from the sun and the seventh largest planet in the solar system. It was also called Yinghuo in ancient China because Mars is red, like fire, and its brightness often changes;Moreover, it moves in the sky, sometimes from west to east, and sometimes from east to west. The situation is complicated and confusing, so in ancient China, it was called "Yinghuo"flame, leaving the confusion. "Meaning.
Mars（Greek: Ἄ ρη, transliteration“Ares”）It is called God of War.This may be due to its bright red color;Mars is sometimes called the "red planet".(Interesting note: Before the Greeks, the ancient Romans worshiped Mars as the god of farming, while the Greeks who were aggressive and expansionist used Mars as a symbol of war.) And the name of March also came from Mars.
Detection history
Discovery:MarsPrehistoric eraAlready known to mankind.Because it is considered to be the best place for human beings in the solar system (except the Earth), it is loved by science fiction writers.But unfortunately, the famous "canal" that Lowell "saw" and other things are just as fictional as the Princess Barsoomian.
visit:The first exploration of Mars was conducted byMariner 4 The aircraft was carried out in 1965.People have made several attempts in succession, including two in 1976Viking Aerocraft.After 20 years, on July 4, 1997,Mars Pathfinder Finally successfully landed on Mars.
The thin atmosphere of Mars is mainly left by the remnantcarbon dioxide(95.3%) plusnitrogen（2.7%）、argon (1.6%) and trace oxygen (0.15%) andsteam(0.03%).Average size of the Martian surfacepressureThe strength is only about 7 mbar (less than 1% on the earth), but it changes with the height, up to 9 mbar at the deepest part of the basin, while only 1 mbar at the top of Olympus.But it is also enough to support hurricanes and large storms that occasionally sweep the entire planet all month long.The thin atmosphere of Mars can also producegreenhouse effectBut those that can only raise the temperature of its surface by 5K are much less than those of Venus and Earth as we know.
The poles of Mars are permanently covered by solid carbon dioxide（dry ice）Covered with.The structure of the ice cover is stacked, which is made up of the ice layer and the changing carbon dioxide layer in turn.In the northern summer, carbon dioxide sublimates completely, leaving the remaining ice water layer.Since the carbon dioxide in the south has never completely disappeared, we cannot know whether there is an ice water layer under the ice in the south.The reason for this phenomenon is unknown, but it may be due to the angle between the equatorial surface of Mars and its orbitLong term changesCaused by climate change.There may also be water deep below the surface of Mars.This kind of bipolar caused by seasonal changesoverburdenThe change caused the pressure of Mars to change by about 25% (measured by Viking).
However, the observation with the Hubble telescope showed that the Viking environment was not typical.The atmosphere of Mars seems to be colder and drier than that detected by Viking (see the STSCI site for details).
Surface topography
In addition to Earth, Mars is a solid surface planet with the most interesting terrain.There are some spectacular landforms:
－OlympusIt is 24 kilometers (78000 feet) high on the surface and is the largest volcano in the solar system.Its base is 600 kilometers in diameter and surrounded by a cliff up to 6 kilometers (20000 feet) high;
- Tharsis: a huge bulge on the surface of Mars, about 4000 km wide and 10 km high;
- Valles Marineris: 2 to 7 kilometers deep,Is long4000 km canyon group;
- Hellas Planitia: an impact crater located in the southern hemisphere, more than 6000 meters deep and 2000 kilometers in diameter.
The surface of Mars has many old craters.But there are also many valleys, ridges, hills and plains that have not formed long ago.
In the southern hemisphere of Mars, there is a curved ring-shaped highland similar to that on the moon.On the contrary, its northern hemisphere is mostly composed of newly formed low and flat plains.The formation process of these plains is very complicated.There is a huge height change of several thousand meters on the north-south border.The reason for the great difference in terrain between the north and the south and the high upheaval in the border area is still unknown (some people speculate that this is due to the huge increase in the outer layer of MarsForceFormed).Some scientists began to doubt whether those steep mountains were in their original places.This doubt will be solved by the "Mars Global Surveyor".
There were floods on Mars and some small rivers on the ground, which clearly proved that many places had been eroded.In the past, there was clean water on the surface of Mars, and there may even have been large lakes and oceans.But it seems that these things only exist for a short time, and it is estimated that they have existed for about 4 billion years.(Valles Marneris is not formed by flowing water. It is formed by the extension and impact of the shell, accompanied by Tharsis bulge).
In the early days of Mars, it was very similar to the Earth.Like Earth, almost all carbon dioxide on Mars is converted into carbonaceous rocks.However, due to the lack of plate movement of the Earth, Mars cannot recycle carbon dioxide into its atmosphere again, so it cannot produce a significant greenhouse effect.Therefore, even if it is pulled to the same distance from the Earth to the sun, the temperature on the surface of Mars is still much colder than that on the Earth.
Internal situation
The internal conditions of Mars are only inferred from its surface conditions and a large number of relevant data.It is generally believed that its core ishigh-densityMaterial composition;Wrapped with a layer of lava, it is thicker than the earth's mantle;The outermost layer is a thin shell.Compared with other solid planets, Mars has a lower density, which indicates that,Martian nucleusIron (magnesium andIron sulfide）It may contain more sulfur.
Like Mercury and the moon, Mars also lacks active plate movement;There is no evidence that Mars has ever happened, which can cause as much damage as EarthFolded mountain systemThe crustal translation activity.Since there is no lateral movement, the huge thermal zone under the crust is located atQuiescent state。In addition, the slight gravity of the ground caused Tharis bulge and huge volcano.However, no evidence of volcanic activity has been found.Although Mars may have had a lot of volcanic activity, it seems that it has never had any plate movement.
About life on Mars
Viking tried to make experiments to determine whether there was life on Mars, but the results were negative.But optimists point out that there are only twoSmall sampleIt is qualified and not from the best place.Future Mars explorers will continue more experiments.
A small meteorite (SNC meteorite) is believed to come from Mars.
On August 6, 1996, David McKay and others announced that organic matter was first found in meteorites on Mars.The author even said that this composition, together with some other minerals obtained from meteorites, could prove to be a Mars paleomicrobe.
Such an amazing conclusion, but it does not make the conclusion that there are aliens.Since David Zhukai gave his opinion, some studies of opponents have also been published.However, any conclusion should be "reasonable and well grounded".There is still much to be done before the conclusion is announced with complete certainty.
Other properties
MartiantropicThe area has a large area with weak gravity.This was an unexpected discovery made by the Mars Global Surveyor when it entered Mars orbit.They may have been left behind when the early shells disappeared.This may be very useful for studying the internal structure of Mars, the pressure in the past, and even the possibility of the existence of ancient life.
In the night sky, it is easy to see Mars with the naked eye.Because it is very close to the earth, it looks very bright.Mike Harvey's planet finding chart shows the positions of Mars and other planets in the sky.More and more details, better and better charts will be discovered and completed by astronomical programs such as Starlight.
The orbit of Mars is remarkably elliptical.Therefore, the perihelion andApohelionThe temperature difference between them is nearly 30centigrade。This has a huge impact on the climate of Mars.The average temperature on Mars is about 218K (- 55 ℃, - 67Fahrenheit degree）However, it has a span from 140K (- 133 ℃, - 207 ℉) in winter to nearly 300K (27 ℃, 80 ℉) in summer and daytime.Although Mars is much smaller than Earth, itsSurface areaIt is equivalent to the land area of the earth's surface.
Jupiter
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English name: Jupiter
Jupiter is the fifth planet from the sun, which was calledOld StarBecause its revolution is exactly 12 years, that is, one branch. Jupiter is the most massive planet in the solar system. Its mass is 2.5 times the sum of all the other seven planets, or 318 times the Earth, and its volume is 1316 times the Earth. Because of its huge size, people can see it without telescopes. Jupiter is called the "king of the planets in the solar system".It has the fastest rotation speed in the whole solar system.
Jupiter (called Zeus by the Greeks) is the king of the divine world, the ruler of Mount Olympus and the protector of the Roman state. It is the son of Cronus (Saturn).
Detection history
Discovery:Jupiter is the fourth brightest object in the sky (aftersunlight, the moon and Venus;Sometimes Mars is brighter), Jupiter has been known as early as prehistoric.According to Galileo in 1610, four satellites of Jupiter:Io，Europa，GanymedeandGanymede(Now often calledGalileo satellite）They are the first discovery that they do not revolve around the earth and agree with CopernicusHeliocentric theoryAboutPlanetary motionThe main basis of;Galileo's outspoken support of Copernicus's theory led toInquisitionHe was arrested and forced to abandon his belief and spent the rest of his life in prison.
Jupiter consists of 90% hydrogen and 10% helium（Atomic number75/25% by mass) and trace methane, waterammoniaAnd "stone".This is very similar to the composition of the original solar system nebula that formed the entire solar system.Saturn has a similar composition, but Uranus and Neptune have less hydrogen and helium.
Gaseous planets have no solid surface, and their density of gaseous matter only increases with the depth (from their surface, we are equivalent to 1pressureTheir radius and diameter are calculated from).What we see is usually the top of the clouds in the atmosphere, and the pressure is slightly higher than one atmosphere.
The inner core is the gathering place of most planetary materialsLiquid metal hydrogenExists in the form of.The most common formal basis on Jupiter may only exist at the pressure of 4 billion pascals, which is the environment inside Jupiter (as is Saturn).Liquid metal hydrogen consists of ionized protons and electrons (similar to the inside of the sun, but much cooler).Under the temperature and pressure inside Jupiter, hydrogen is liquid rather than gaseous, which makes it the electronic conductor and source of Jupiter's magnetic field.Similarly, this layer may also contain some helium and trace "ice".
Jupiter may have a rocky core, which is equivalent to the mass of 10-15 Earths.
The outermost layer is mainly composed of ordinary hydrogen and helium molecules, which are liquid inside and gasified outside. What we can see is the higher part of this deep layer.Watercarbon dioxideMethane and other simple gas molecules also have a little here.
It is believed that there are ammonia ice and ammonium water in the three distinct layers of cloud layersulfideandIce water mixture。However, the preliminary results from the Galileo certification show that these substances are extremely rare in the clouds (one instrument seems to have detected the outermost layer, and the other may have detected the second outer layer at the same time).However, the surface location proved this time is very unusual - based on Earth's telescope observation and more from Galileo's orbit, the spacecraft observation suggested that the selected area for this demonstration was probably the warmest and least cloudy area on Jupiter's surface at that time.
Surface hurricane
There are high-speed hurricanes on the surface of Jupiter and other gaseous planets, and they are confined in a narrow latitude range, and the direction of wind blowing at close latitudes is opposite.Slightchemical compositionAnd temperature changes have created colorful surface belts that dominate the appearance of planets.LuminousSurface bandThey are called zones, and dark ones are called belts.The ribbons on Jupiter have been known for a long time, but the vortex at the border of the ribbons isVoyagerThe first discovery of a spaceship.The data sent back by the Galileo spacecraft showed that the surface wind speed was much faster than expected (more than 400 miles per hour), and extended to the same depth as the root could observe, about thousands of kilometers inward.Jupiter's atmosphere is also found to be quite disordered, which indicates that hurricanes move rapidly in most parts due to its internal heat, unlike the Earth, which only gets heat from the sun.
Surface cloud layer
The colorful clouds on Jupiter's surface may be caused by the subtle differences in the chemical composition of the atmosphere and its role. It may be mixed with sulfur compounds, creating a colorful visual effect, but its details are still unknown.
The change of color is related to the height of clouds: the lowest part is blue, followed by brown and white, and the highest part is red.We can see the lower clouds only through the holes in the higher clouds.
The great red spot on the surface of Jupiter was known by Earth observation 300 years ago (this discovery is often attributed to Cassini, or Robert Hook in the 17th century).The Great Red Spot is an ellipse with a length of 25000 kilometers and a span of 12000 kilometers, which can accommodate two Earths.Other smaller spots have also been seen for decades.infraredThe observation and deduction of its rotation trend show that the Great Red Spot is a high pressure area, where the top of the cloud layer is particularly high and cold than the surrounding area.A similar situation exists on Saturn and Neptune.It's not clear whyClass structureCan last that long.
Energy and radiation
The investigation of Jupiter shows that Jupiter isCosmic spaceRelease huge energy.It emits twice as much energy as it obtains from the sun, which indicates that JupiterRelease energyHalf of it comes from inside.There is a heat source inside Jupiter.As we all know, the reason why the sun continuously emits a lot of light and heat is becauseInside the SunAll the timenuclear fusionReaction, which releases a lot of energy in the process of nuclear fusion.Jupiter is a giantLiquid hydrogenThe planet itself has incomparable naturenuclear fuel, plus Jupiter'sCenter temperatureIt has reached 280000 K and is ready to carry outThermonuclear reactionHigh temperature conditions required.As for the high pressure conditions required for thermonuclear reaction, according to the contraction speed of Jupiter and the accretion characteristics of energy released to the sun and energy carrying particles, after several billion years of evolution, Jupiter's central pressure can reach the initial nuclear pressureReaction timeRequired pressure level.Once there is a large-scale thermonuclear reaction on JupiterJupiter's atmosphereIt will act as a "transmitter" to release nuclear heat.Therefore, some scientists speculate that after several billion years, Jupiter will change its identity from a planet to a star worthy of the name.Jupiter is very similar to the sun in composition, but it doesn't burn like the sun because its mass is too small.To become a star like the sun, Jupiter needs to increase its mass to 70 times.
Jupiter outwardRadiant energy, more than received from the sun.Jupiter's interior is very hot: the core may be as high as 20000 Kelvin.The heat output is determined byKelvin Helmholtz principleThe planet's slow gravitational compression. Jupiter is not like the sunnuclear reactionThe condition for generating energy, which is too small to cause nuclear reaction due to insufficient internal temperature.)The heat generated inside may have greatly triggered the convection of Jupiter's liquid layer, and caused the complex moving process of the cloud top seen by us.Saturn and Neptune are similar to Jupiter in this respect, but Uranus is not.
Jupiter has the same maximum diameter as a gaseous planet.If the composition increases again, it will be compressed by gravity, making the global radius only slightly increased.The enlargement of a star can only be attributed to the internal heat source (nuclear energy), but if Jupiter wants to become a star, its mass must be at least 70 times larger.
Galileo spacecraft's detection of Jupiter's atmosphere was found inJupiter RingAnd the outermost atmosphereradiation zone, roughly equivalent tothe ionosphereTen times the radiant zone.Surprisingly, the newly discovered band contains high-energy helium ions from unknown sources.
magnetic field
Jupiter has a huge magnetic field, which is much larger than the Earth's,MagnetosphereExtending outward more than 6.5 × 10sevenKilometers (beyond Saturn's orbit).(Note: Jupiter's magnetosphere is not spherical, it just extends towards the sun.) In this way, Jupiter's satellites will always be in Jupiter's magnetosphere, and some of the resulting conditions areIoThere arePartial explanation。Unfortunately, for future space walkers and experts who devote themselves to the design of Voyager and Galileo, the high-energy particles captured by Jupiter's magnetic field in the nearby environment will be a big obstacle.This kind of "radiation" is similar to, but much stronger than, the situation in the Earth's ionospheric belt.It will immediately have a fatal impact on unprotected humans.
Jupiter Ring
Jupiter has a ring like Saturn, but it is small and weak.Their discovery was totally unexpected, but only because two Voyager 1 scientists insisted on sailing 1 billion kilometers, they should go to see if there is a halo.Others believe that the possibility of discovering halos is zero, but in fact they exist.What a clever plan these two scientists have come up with.They were later photographed by telescopes on the ground.
Jupiter's ring is not like Saturn's, Jupiter's ring is darker（AlbedoIs 0.05).They are composed of many granular rocky materials.
The particles in Jupiter's ring may not exist stably (due to the effect of atmosphere and magnetic field).In this way, if the halos are to remain in shape, they need to be constantly replenished.Two small satellites orbiting in the halo:Ganymede 16andGanymede XVII, obviously the best candidate for Halo Resources.
Jupiter's moons
Jupiter has 66 known satellites, 4 satellites discovered by Galileo, and 62 smaller ones.
Due to the Galileo satelliteTidal force, Jupiter is gradually movingGeostrophic changeSlow.Similarly, the same tide generating force has also changed the orbit of satellites, making them gradually move away from Jupiter.
Io, Europa, and Ganymede are affected by the tide generating forcerevolutionThe co movement relationship is fixed at 1:2:4 and changes together.GanymedeIt is also a part of this.In the next few hundred million years, Ganymede will also be locked, with twice the revolution cycle of Ganymede,IoEight times of.
Jupiter's moons were named after the people Zeus had touched in his life (mostly his lovers).
Satellite distance (km) radius (km) mass (kg) discoverer discovery date
SaturnIt is the sixth planet far from the sun and the second largest of the eight planets. It was called“Saturn”, the smallest planet in the solar system, can float on water.
Basic parameters
Orbit of revolution: 1429400000km (9.54 km) from the sunAstronomical unit）
Rotation direction: from west to east
Planetary radius: 60268km (equator)
Quality: 5.68 × 10twenty-sixkg
Number of satellites: 83
Name Source
In Roman mythology, Saturn“Saturnus”Yesgod of agricultureThe name of the.Cronus, the god of agriculture in Greek mythology, is Uranus（Uranus）And Gaia's son, Zeus（Jupiter）'s father.Saturn is also "Saturday" in English（Saturday）The root of.
Detection history
Discovery:Saturn was discovered in prehistory.GalileoIn 1610, he first observed it through a telescope and recorded its strange trajectory, but he was also confused by it.Early observations of Saturn were very complicated, because every few years when Saturn was in its orbit, the Earth would pass throughSaturn's ringsThe plane where it is located (low resolution Saturn pictures often have radical changes), until 1659 when Huygens correctly deduced thegeometry。Before 1977, Saturn's rings were considered to be unique in the solar system;But in 1977, faint rings were found around Uranus, and soon after that, rings were also found around Jupiter and Neptune.
visit:Pioneer 11 first visited Saturn in 1979, and was visited by Travelers 1 and 2 in the same year.The Cassini spacecraft also reached Saturn in 2004.
nature
Saturn and its rings
It is also obvious that Saturn is aOblate sphere。Its equatorialDiameter ratioThe diameter of the poles is about 10% larger (120536 km at the equator and 108728 km at the poles), which is the result of its rapid rotation and the liquid surface.Other gaseous planets are also oblate spheres, but not so obvious.
Saturn is the most loose planet, and its specific gravity (0.7) is smaller than water.
Like Jupiter, Saturn is composed of about 75% hydrogen, 25% helium and a small amount of water, methane,ammoniaAnd some rock like materials.These compositions are similar to the formation of the solar system,Solar nebulaThe composition of matter.
Like Jupiter, the interior of Saturn consists of a rock coreMetallicityA liquid hydrogen layer and a hydrogenMolecular layerAt the same time, there is a small amount of ice of all kinds.
The interior of Saturn is extremely hot (up to 12000 K in the core), and Saturn sends more energy to the universe than it gets from the sun.Most of the extra energy, like Jupiter, is generated by the Kelvin Helmholtz principle.But this may not be enough to explain Saturn's luminous power. Some other functions may also be in progress, which may be caused by the "washing" of helium deep inside Saturn.
The obvious bands on Jupiter are much more blurred on Saturn, and become wider near the equator.Since the Earth could not see its top clouds clearly, people did not begin to study the atmospheric cycle of Saturn until a tourist spaceship accidentally observed it.Like Jupiter, Saturn haslong periodOfElliptical orbitAnd other general characteristics.In 1990, the Hubble telescope observedSaturn equatorA very large white cloud nearby, which did not exist when Voyager arrived;In 1994, another smaller storm was observed.
Saturn's rings
Two obvious rings (A and B) and a dim ring (C) can be seen from the earth. The gap between A ring and B ring is called "Cassini part".A more dim gap in the outer part of the A halo is called "Encke Gap" (but this is a bit of a misnomer, because it may never be seen by Encke).The pictures sent back by Voyager showed four faint rings.Saturn's ring is different from that of other stars. It is very bright.(star albedo is 0.2-0.6)
Although the rings are continuous from the earth, they are actually composed of countless tiny objects in their own independent orbits.Their size ranges from 1 cm to several meters, and there may be some objects with a diameter of several kilometers.
Saturn's rings are particularly thin. Although they are 250000 kilometers or more in diameter, they are only 1.5 kilometers thick at most.Although they have impressive and obvious images, there are only a few substances in the halo - if the halo is compressed into an object, it can only be 100 kilometers wide at most.
The particles in the halo may be mainly composed of ice condensed by water, but they may also be rock like particles wrapped in the outer layer of ice.
Voyager confirmed puzzling radiusNonuniformityIt does exist in the aura, which is called "spokes"Amateur astronomerReported.Their natural nature gives us a mystery, but it gives us clues to the magnetic field of Saturn.
Saturn's outermost ring, F-ring, is a complicated structure composed of smaller rings“Knot(Knots) "is obvious.Scientists speculate that these so-called knots may be massive halo materials or some mini moons.These strange fabrics are obvious in the image sent back by Voyager 1, but they cannot be seen in the image sent back by Voyager 2, probably because the composition of the halo part taken by the latter is slightly different from the former.
There are complextideresonancePhenomenon: some satellites, the so-called“shepherd satellite ”(e.gAtlas，PrometheusandPandora）It is obviously important to maintain the shape of the halo;EnceladusIt seems that we should be responsible for the lack of certain substances in Cassini, which is related toAsteroid beltThe situation encountered by Kirkwood gaps in is similar;panIn the Encke Gap.The whole system is too complex, and what we have mastered is still very poor.
Saturn (and othersJupiter like planet）The origin of the halos is not clear. Although they may have halos since their formation, the halo system is unstable. They may be constantly updated in the process of progress, or they may be fragments of larger satellites.
Halo data
Halo distance (km) width (km) mass (kg)
D 67000 7500
C 74500 17500 1.1e18
B 92000 25500 2.8e19
Cassini part
A 122200 14600 6.2e18
F 140210 500
G 165800 8000 1e7?
E 302000 [32000 km] 300000
(Distance refers to the distance from the center of Saturn to the inner edge of the halo) This classification is really misleading, because the density of particles changes in a complex way, and cannot be divided into a clear area by classification: there are constant changes in the halo;Those gaps are not all empty, and these rings are not a standard ring.
Like othersJupiter like planetSimilarly, Saturn has a very meaningful magnetic field.
Saturn is easy to see in the endless night sky.Although it may not be as bright as Jupiter, it is easy to recognize it as a planet because it does not "twinkle" like a star.The ring and its satellites can be observed through a small amateur astronomical telescope.
Moons of Saturn
Saturn has 18 named moons, more than any other planet.Some small satellites will also be discovered.
Among those satellites whose rotational speed is known, exceptIapetusandTitanAll are synchronized.A total of 60 satellites have been discovered.
There are three pairs of satellites, Iapetus - Iapetus,Enceladus-Enceladustitan-Titan has gravitational interactions to maintain a fixed relationship between their orbits.EnceladusThe revolution period happens to beEnceladusIt can be said that in the 1:2 co kinetic relationship, Enceladus-EnceladusIs also 1:2;Titan-TitanThe relationship is 3:4.
In addition to 18 named satellites, at least a dozen have been reported and given temporary names.
Satellite distance (km) radius (km) mass (kg) discoverer discovery date
UranusIt is the seventh planet far from the sun in the solar system and the coldest planet in the solar system. In terms of diameter, it is the third largest planet in the solar system.Uranus is larger in volume than Neptune, but smaller in mass.
Orbit of revolution: 2870990000 km (19.218 AU) from the sun
Rotation direction: from east to west
Planet radius: 25559 km (equator)
Mass: 8.683 × 10twenty-fiveKg
Number of satellites: 29
Name Source
UlanosIt is the god of the universe in ancient Greek mythology and the earliest supreme god.He isGaiaThe son and spouse of Cronus, the Cyclops, andTitanFather of Olympus.
Detection history
Uranus
Discovery:Uranus was passed by William HerschelTelescope systemEarth search, discovered on March 13, 1781, is the first planet discovered in modern times.In fact, it has been observed many times, but it was mistaken as another star at that time (John Flamsteed had observed its existence as early as 1690, but at that time it was classified as 34 Tauri).Herschel named it "the Georgia Sidus" (geranium, also known as "Georgia planet") to commemorate his sponsor, who is notorious to AmericansKing of England：George III；Others call Uranus Herschel.Because the names of other planets are taken fromMYTHOSTherefore, in order to maintain consistency, Bode first proposed to call it "Uranus", but it was not widely used until 1850.
visit:Only oneInterstellar probeHe once visited Uranus, which was completed by Voyager 2 on January 24, 1986.
rotation
Most planets revolve around an axis almost perpendicular to the ecliptic plane, but Uranus's axis is almost parallel to the ecliptic plane.During the period of Voyager 2 exploration, the south pole of Uranus was almost acceptedDirect sunlightOf.This strange fact shows that the energy from the sun in the polar regions of Uranus is more thanequatorWhat the region gets is higher.However, the equatorial region of Uranus is still hotter than the polar region.The reason for this is still unknown.
And it either rotates in the forward direction at a shaft angle greater than 90 degrees, or rotates in the reverse direction at a tilt angle less than 90 degrees.The problem is that you have to draw a line somewhereDividing lineFor example, whether Venus is realCounter rotation(Not the forward rotation with an inclination of nearly 180 degrees).
form
Uranus is basically composed of rocks and various kinds of ice. It contains only 15% hydrogen and some helium (less than Jupiter and Saturn, which are mostly composed of hydrogen).Uranus and Neptune are in many ways similar to Jupiter and Saturn in removing the hugeLiquid metal hydrogenThe kernel behind the shell is very similar.Although the core of Uranus is not composed of rocks like Jupiter and Saturn, their material distribution is almost the same.
atmosphere
Uranus's atmosphere contains about 83% hydrogen, 15% helium and 2% methane.
As all othersGaseous planetSimilarly, Uranus has ribbons of clouds floating around it.But they are so weak that they can only be seen from the processed pictures of Voyager 2.Observations from the Hubble telescope show that the stripes are larger and more obvious.It is speculated that this difference is mainly due to the effect of seasons (the sun shining directly into a certain low latitude region of Uranus may cause an obvious effect of day and night).
Uranus appears blue because methane in its outer atmosphere absorbs red light.There may be ribbons like Jupiter's, but they are covered with methane.
Other properties
Voyager 2 found five knownLarge satelliteThe next 10 small satellites.It seems that there are some smaller satellites in the halo.
When it comes to the rotation axis of Uranus, it is also worth mentioning that its magnetic field is also very strange. It is not at the center of the planet, but tilted nearly 60 degrees.This may be caused by the deep motion inside Uranus.
Sometimes, in a clear night sky, you can just see the blurred Uranus with the naked eye, but if you know its position, you can easily observe it through binoculars.A small disk can be seen through a small astronomical telescope.Mike Harvey's Planet SearchChart displayThe position of Uranus and other planets in the sky.More and more details and better charts will be shown asBrilliant Milky WaySuch astronomical procedures to discover and complete.
Uranus's moons
Uranus has 25 named moons and 2 discovered but unnamed moons.
Unlike other celestial bodies in the solar system, the satellites of Uranus are not named after people in ancient myths, butShakespeareAnd Romethe pontiffThe names of the characters in his works.
They are naturally divided into two groups: 10 very dark small satellites near Uranus and 5 large satellites in the outer layer discovered by Voyager 2.
They all have a circular orbit around the equator of Uranus (thus relative toEquatorial surfaceHas a larger angle).
Satellite distance (km) radius (km) mass (kg) discoverer discovery date
Like all other gaseous planets, Uranus has rings.They are as dark as Jupiter's halo, but like Saturn's halo, they are composed of very large particles with a diameter of 10 meters and fine dust.Uranus has 11 known rings, but they are very dim;The brightest one is calledEpsilon Halo。Uranus's ring is the first to be discovered after Saturn's discovery, which is considered very important. From this, we know that the ring is a common feature of the planet, not only unique to Saturn
Halo distance (km) width (km)
1986U2R 38000 2,500
6 41840 1-3
5 42230 2-3
4 42580 2-3
Alpha 44720 7-12
Beta 45670 7-12
Eta 47190 0-2
Gamma 47630 1-4
Delta 48290 3-9
1986U1R 50020 1-2
Epsilon 51140 20-100
(Distance refers to the length from the center of Uranus to the inner edge of the halo)
Neptune
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English name: Neptune
NeptuneIt is the eighth planet orbiting the sun and the fourth largest celestial body (in diameter) in the solar system.Neptune is smaller in diameter than Uranus, butmass ratioIt's big.
Basic parameters
Orbit of revolution: 4504000000 km (30.06 km) from the sunAstronomical unit）
Rotation direction: from west to east
Planet radius: 24718km (equator)
Quality: 1.0247 × 10twenty-sixkg
Number of satellites: 14
Name Source
In ancient Roman mythology, Neptune (ancient Greek mythology:PoseidonPoseidon) stands for Poseidon.
Detection history
Discovery:Neptune is a planet discovered by formula rather than purposeful observation.After the discovery of Uranus, people noticed its orbit andNewtonWhat the theory infers is inconsistent.So scientists predict the existence of another distant planet that will affect the orbit of Uranus.Galle and d'Arrest observed Neptune for the first time on September 23, 1846. It appeared very close toAdams And Leveyer based on the observations of JupiterSaturnAnd Uranus are independently predicted by calculation.A scene about who discovered firstNeptuneThe international dispute over who has the right to name it originated between Britain and France (however, there was no obvious dispute between Adams and Le Vie personally);The discovery of Neptune was attributed to both of them.Later observations showed that the orbit calculated by Adams and Leveyer was similar to the real orbit of NeptuneTrack deviationQuite large.If the search for Neptune had been carried out a few years earlier or later, people would not have been able to find it at or near its predicted location.
visit: Only onespacecraftVoyager 2He visited Neptune on August 25, 1989.Almost all the information we know about Neptune comes from this brief meeting.
Track and composition
becausePlutoIts orbit is extremely strange, so it sometimes passes through the orbit of Neptune. Since 1979, Neptune has become the planet actually farthest from the sun, and Pluto will become the most distant planet again in 1999.
Neptune's composition is similar to Uranus's: various "ice" and rocks containing 15% hydrogen and a small amount of helium.Neptune is similar to Uranus but different from Saturn and Jupiter. It may have obvious internal geological stratification, but its composition is more or less consistent.But Neptune probably has a small, rockyearth 's core(The mass is similar to that of the earth).Its atmosphere is mostly composed of hydrogen and helium.There are a fewmethane。
Large black spot
During Voyager 2's visit to Neptune, the most obvious feature on the planet is thatsouthern hemisphereOfBlack spot（The GreatDark Spot).The black spot is about the size of JupiterGreat erythema50% (the diameter is similar to that of the Earth), and the high wind on Neptune is 300Meters per second（700Miles per hour）Speed handleLarge black spotBlow westward.Voyager 2 also found a small black spot in the southern hemisphere, a small irregular cloud of white smoke that flew around the planet at a speed of about 16 hours. It was known that it was "The Scooter".It may be a ball fromatmosphereAscendingPinnateBut its true nature is still a mystery.
However, in 1994Hubble telescopeThe observation of Neptune shows that the big black spot has disappeared.It may have dissipated in this way, or be temporarily covered by other parts of the atmosphere.A few months later, the Hubble telescopeNorthern HemisphereA new black spot was found.This indicates that Neptune's atmosphere changes frequently, which may be caused by the slight change of temperature difference between the top and bottom of clouds.
Other properties
Neptune's blue color is caused by the absorption of red light from sunlight by methane in the atmosphere.
As a typical gas planet, Neptune is roaring with large storms or cyclones in zonal distribution. Neptune's storms are the fastest in the solar system, with a speed of 2000 kilometers per hour.
Like Saturn and Jupiter, Neptune has a heat source inside -- it radiates more than twice the energy of the solar energy it absorbs.
The magnetic field of Neptune is the same as that of Uranus, and its position is very strange, which is probably due to the middle layer of the planet crustConductivityIt is caused by the movement of substances (probably water).
adoptBinocular telescopeNeptune can be observed (if you really know where to look), but if you want to see everything on the planet instead of just a small disk, then you need a largeAstronomical telescope。Mike Harvey's planet search chart points out the position of Neptune in the sky at this time (and the position of other planets), and then Starry Night will make more and more detailed customization.
NeptuneThere is also aura.Only dim and fuzzy arcs, not complete halos, can be observed on the earth.But Voyager 2image displayThese arcs are rings of light.One of the rings seems strangeSpiralStructure.
Like Uranus and Jupiter, Neptune's rings are very dim, but their internal structure is still unknown.
People have named Neptune's halo: the outermost one is Adams (it includes three obvious arcs, which have been named Liberty, EqualityEqualityFraternity), followed by an unnamed packageGalateaThe arc of the satellite, then the Leverrier (its outward extension is called Lassell and Arago), and the innermost dim but wide is called Galle.
Halo distance (km) width (km)
Diffuse 41900 15 1989N3R,Galle
Inner 53200 15 1989N2R，Leverrier
Plateau 53200 5800 1989N4R,Lassell,Arago
Main 62930 50 1989N1R,Adams
Delisted planet
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Pluto HD
Discovered by American astronomer Tom Bo in 1930PlutoIt was once thought to be a planet, but on August 24, 2006International Astronomical UnionThe 26th General Assembly was voted by more than 2000 astronomers - there are only eight planets in the solar system, no longer the traditionalNine planetsPluto, as one of the planets, is listed“dwarf planet”。[2]
2、 The mass is large enough to make the celestial body spherical by its own gravity.
3、 Can gradually clear the celestial body near its orbit.
Pluto is not consistent with the third article, and Pluto's satellite（Charon ）It is too huge to formDouble planetSystem, so according to this definition, Pluto is removed from the list and listed as a dwarf planet.
Suspicious planets
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Kuiper beltIt is a space region beyond the orbit of Neptune, in which there are cold, rocky objects everywhere.The accepted solar system theory believes that the orbital distribution of celestial bodies beyond Neptune's orbit should be random, plus observation deviation,Track semimajor axisNear 150 AU, the orbital inclination is almost 0 °, perihelionRadial angleIt should also be close to 0 ° or 180 °, which has been found in the Kuiper beltCharon、Eris 、sedna Wait for more than ten extremesOverseas celestial bodiesThe semi major axis of the orbit in the is extremely different (between 150 and 525 AU), and the inclination of the orbit isaverage valueIt is about 20 °, and the perihelion radiation angle is – 31 °. No object is close to 180 °.
Of these starsTrack parametersIt seems to be affected by other stars. There may be other unknown planets besides Neptune and Pluto.In 2015, two American scientists found adwarf starPlanet, named 2012VP113.The two discoverers believe that its orbit may be affected by a black and iceSuper EarthIts size can reach 10 times that of the earth.[4]
Memory method
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Simple notation: Five Elements（Jinmu Shuihuo Earth）+Sea, land and air (Sea King, Earth and Sky King)
Other notation is: water, gold, earth, fire, wood, earth, sky, sea.It's long but easy to remember.
There is another kind of notation, although it is somewhat far fetched, but the memory is kept for a long time: "crystal balls, burning wood, turned into earth, the ends of the earth."
There is also a notation, "The water overflows the golden mountain, the fire burns the wood and scorched earth, and the sky and the sea become onesolar system”。
