The Moon Sea in the Eastern Dangerous Sea Basin on the Front of the Moon
Dangerous sea(Mare Crisium) is located inThe front of the moonOne of the eastern dangerous sea basinsMoon Sea, located within 560 × 420 km, covering an area of nearly 176000square kilometreThe surface is extremely flat.It is the loneliest sea on the front of the moon: surrounded by vast highlands, only a few scattered small moon sea areas are interspersed.There areMass tumor, wrinkling andImpact craterBut no similarrille OfGraben。
AndMoonLike most of the moon sea on the moon, the dangerous sea was named by Giovanni Battista Rijoli in 1651 and was named in 1935International Astronomical UnionFormal acceptance.
In ancient times, the Moon Sea had some other names, which might have been calledCaspian SeaBecause in 1600, British astronomersThomas Harriot This name has been specially recorded;FrancePierre Gassendi (1635 – 1637) and Michael Florent Van Langen (1645) in theirLunar chartMedium, andancient GreekwriterPlutarchThey all call it the Caspian Sea.Eun Adair Whitaker speculates that this is because itMoonThe position on is similar to that in EuropeNorth AfricaandMiddle EastIn the regional mapCaspian SeaPosition on the earth.However, in 1647Johannes Hevelius But withAzov SeaIn ancient times, it was named "Miotis Lake" or "Palus M ∨ otis";In addition, around 1600, British astronomersWilliam GilbertIn his famous lunar chartGreat BritainIt is called Brittania.
Location and surrounding landform
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The coordinate of dangerous sea lunar surface is 17.0 ° N 59.1 ° E, adjacent to Jinghai andMengnuma, southwest and east are respectively locatedFengfuhaiandBoundary sea, in dangerous seas andBoundary seaThere is also a group of people informally called "Lissus Felix Lake" or "Laughing Cat Lake" (Latin name:Lacus Risus Felis）Small ofMoon Sea。
Close to the western edge of the dangerous sea, there is also a strikingStriae shooting systemProclos Crater, other named craters adjacent to the Moon SeaLunar craterYes: west sideMarkrobius crater, Tislang Crater, Glacier Crater, Fredholm Crater, and Kriel Crater;Delmot crater and Einmert crater in the north;Al Hakim crater and Hansen crater in the east and Aozu crater, Van Albada crater, Shapley crater and Tebat crater in the south.
basin
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LikeMoonMany othersMoon SeaSimilarly, the dangerous sea is also located in a huge impact basin, occupying the deepest part, surrounded by a ring of mountains.The circular mountain range is slightly longer from east to west, covering 630 × 500 kilometers.The western edge is almost complete and continuous, while the eastern edge is fragmented.In addition, some large and small relic rings can also be vaguely seen overlapping in the basin. The smallest ring in the ring mountain range is about 380 kilometers in diameter, but the largest may be 1000 kilometers, or even 1600 kilometers.
Weihai Basin is one of the most flat and long large craters on the moon, and its outer mountain ring is also very eye-catching (but not as good as Jiuhai andOriental Sea).OutcastEjectaSeen most clearly in the southeast and northeast, the ejecta produced by the oblique impact formed a butterfly like halo on the moon surface.In addition, a large number of secondary pits are scattered within 1100km from the center of the basin, some of which constituteChain pitOr merge into a continuous valley.
According to gravitydata displayThe dangerous sea basin has been recorded on the moonLunar shellOne of the thinner regions, where the gravity is almost zero, which is mainly caused by the crustal layer being thrown away during the impact.
Lava bed
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The thickness of dangerous sea lava layer measured by different methods is about 1.9-1.8km, of which the place near the edge is the thinnest. There are some remnant pits submerged by magma, but there is no "island" in the center of the moon sea surrounded by lava. The lava solidified in these places spreads over the entire surface, forming the moon sea in the basin as seen today.Apollo 17Detection ofradarIt is shown that there is a layer with slightly different density at a depth of about 1.4 km below the Moon SeaRock stratum(may beRegolith orVolcaniclastic rock）。
Compared with all adjacentMoon SeaLower: quieter sea andWave seaAbout 3 km lower;thanFoam sea、Mercy LakeandChangcun Lake2 km low;relativelySnake SeaandFengfuhai1 km lower.The absolute altitude of its surface is between 3.2-3.8 kilometers.Only its annular ridge has the smallest relative drop, and the peak of the ridge is 3-5 kilometers above the dangerous sea surface.
In 1968, five American shipsLunar orbitThe spacecraft's Doppler mine instrument has detected the largestMass tumorOr high gravity area.LaterOrbiterFor example:Lunar Prospector And the Grail spacecraft have confirmed and accurately mapped the mass tumor.
Surface characteristics
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The western edge of the dangerous sea is relatively flat, but the eastern part is cut by manyYuewan, promontory, peninsula and hills.The largest Moon Cape is located in the southeast and is named Agrum Cape. It is almost an island, because a Moon Bay separates it from the "mainland". However, the Moon Bay is just a light that is not very conspicuous. There is also a named island nearby - Mount Usov.
There is a small valley mouth distributed in the western ridge. The north end is informally called "Promontorium Olivium", and the south end is called "Promontorium Lavinium". Under the oblique sunlight, the two moon headlands seem to be connected by a bridge. This illusion is also called "bridge of O'Neill".
In the dangerous sea, there is a ring of ridges that is more round than itself. The area is 390 × 360 kilometers, about ten kilometers away from the coast of the moon. They are divided into several sections: the west section isOpel RidgeThe east section is the Jiejiayev Ridge, the Hake Ridge is located in the southeast, and the south section isTermie Ridge。According to the measured accurate elevation data of the moon sea, many low ridges (more than 170 tracks) that do not belong to the ring ridge are also found.
Large scale in dangerous seaImpact craterMost of them have been buried by lava, and only a few small craters remain near the edge, of which the Yerkes Crater with a diameter of 35 kilometers, which has been severely damaged, is distributed near the western edge, and the Lik Crater with a diameter of 32 kilometers is similar in the southeast;Picard Crater (22km) is just to the east of Yerkes Crater, and its northwest is Pierce Crater (19km) and Swift Crater (10km);Near the northern side of the Moon Sea is the 23km satellite crater "Einmert C".Some of the remaining ridges in the Moon Sea reveal the existence of some larger impact craters (more than 95 kilometers in diameter) that are now completely covered by lava.The following are some other lunar craters in the dangerous sea: Grievous Crater (14km), satellite craters "Cleomides F" (12km) and "Wallenheit Crater" (7km), Curtis Crater (3km), Eckert Crater (2km), Lev Crater (0.06) km and several satellite craters, all formed after the emergence of lava.stayOpel RidgeThere is another 3 km northConcentric ringThere are also several similar craters located along the southeast edge of the Moon Sea.
Some ray beams from the nearby Proclos crater have crossed the western surface of the lunar sea, while in other regions there are also several faint ray beams from different craters.
Geological history
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The dangerous sea basin was formed inNectarian It is roughly estimated that its geological age is about 3.8-3.9 billion years (based onMoon 20TheRadiometric datingCalculation), compared with the adjacent JinghaiFengfuhaiJiuhai is young, and there may beHumboldt SeaAncient, but it is not clear whether it is more thanChenghaiOlder.Judging from the appearance of the long shape of the basin, the eastern edge of its jagged fault and the distribution pattern of ejecta reflect that it was formed from the oblique impact angle from the west may be less than 15 °.According to another statement, the long and flat appearance of the basin is mainly due to the formation of a large crater on the east surface, or the subsequent collapse of the east surface.
According to the previousSoviet UnionMoon 24SampledbasaltradiationisotopeAccording to the dating, the monthly quality age of Haiti is about 2.5-35 billion years ago.The ages of different areas on the surface of the Moon Sea measured by the crater density range from 2.7 billion to 3.6 billion years (the area near the western edge is the oldest).ThereforebasaltLava may be formed fromLate YuhaiandElatosnian。Some small surrounding areas covered by the lava of that timeMoon SeaorMoon LakeAlso considered to belong toLate Yuhai, but later than the dangerous sea.
After the formation of the basin, over a long period of time, the continuously gushing molten slurry eventually overflowed to Yerkes and Lik craters. After the molten slurry solidified, it experienced continuous meteorite bombardment, forming Picard crater, Pierce crater and many smaller meteorite craters.In addition, the solidified lava has formed a series of ridges (ridges) along the edge of the basin under its own weight.
Observation and exploration
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Because it is close toMonthly chartEdge, sometimes atMoonDuring perturbation, it can be easily observed by the naked eye.
In November 1974,Moon 23In the southeast of dangerous sea（Lunar coordinates12.43°N 62.12°E）Failure due to rollover during landing;
August 18, 1976, 2.3 kilometers away from the moon 23-Lunar coordinates12.7145°N 62.2129°E, close to theLev craterNorthwest pit wall,Moon 24Successful landing and returnearthAt a depth of 2 meters below the 170g moon surfaceLunar regolith。
