Southern cross, one of the constellations in the southern sky, is the smallest of the 88 constellations in the skyCentaur(Centaurus) andMusca(Musca)the galaxyInside.The main bright stars in the constellation form a "cross", and draw down from the vertical bottom of the "cross" until the point about 4 times the length of the vertical isSouthern Celestial Pole。staythe Tropic of CancerThe whole constellation can be seen from the south.New ZealandOur national flag has the southern cross with the epsilon star omitted.andAustralia、papua new guineaandSamoaOur national flag also has the Southern Cross[1]。
The Milky Way, where the Southern Cross is located, is the brightest part of the Milky Way.Its central position: 12:20 right ascension,Declination- 60 degrees.Although the Southern Cross is small, it has many bright stars.Alpha star is a famous bright star in the southern skyKonductraβ star is the first class star, in addition, there are seven stars brighter than the fourth class star.
The main bright stars in the seat are cross I (γ), cross II (α)Cross III(β) AndCross IV(δ) Compositioncross。The south celestial pole is about 4 times the length of the vertical cross.Observed at low latitudes in the Northern Hemisphere, this extension line andhorizonThe intersection point of is basically due south.Since there is no bright star near the South Celestial Pole, Cross 1 and Cross 2 are used to indicate the direction - only the distance between them is extended about 4.5 times to the South Celestial Pole.This cross is as important in the Southern Hemisphere as the Big Dipper is in the Northern Hemisphere.
In addition, CentaurAlpha And the horse bellyVertical bisectorThe intersection with the above extension line will also be the South Celestial Pole.
Observation characteristics
This constellation cannot be seen in most parts of the Northern Hemisphere, but only in several southern provinces.
The latitude range for observing the whole constellation: 25 degrees north latitude toSouth Latitude90 degrees.
It is generally believed that the French astronomer Augustin Royer first converted the Southern Cross fromCentaurIt is set as the constellation.But before that, this constellation has been widely known.
NGC 4755, YesOpen cluster, commonly known as“jewel box ”, also known as the "Southern Cross κ star cluster".yesLakay(Nicolas Louis de Lacaille, 1713-1762) was discovered in 1751 and 52 years. It is about 7500 light years away from the Earth, and contains about 100 stars.It appears to the naked eye as a single star of the fourth order.The main stars of the κ star cluster in the Southern Cross are as follows:
Coalsack Nebula (The Coalsack)Dark nebula, located between α cross andCross IIIA black wedge shaped dustGas nebula, 400 light-years from the earth.At the bottom left of the cross of the Southern Cross, there is a darkDust nebulaAgainst the bright background of the Milky Way, it looks like a dark cave in the Milky Way, called“Coal bag”Its area is almost the same size as the cross, and extends to the adjacent Centaurus and Musca.Coalsack Nebula Located in the Milky Way, it is the most striking in the skyNega Nebulas One is that it can be easily seen with the eyes.
Constellation myth
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Southern Cross
ancientastronomerIt seems that the stars in the Southern Cross areCentaurThey are surrounded by Centaurus in three directions.Victorian scholar RH. In his Star Directory, Allen draws attention to the earlier traditional evidence of the cross.In the 11th century AD, the ancient Arab astrologer Al Boni noticed that30 degrees north latitudeAt, you can see a southern star cluster called Sura.just asAllenAs pointed out, this may provide us with a designDante《Divine Comedy》(early 14th century).When entering the southern hemisphere through the entrance of purgatory, Dante declared, "I focus my mind/attention on the other pole, and I see/only four stars that the original people have seen" (Purgatory 1:22~24).
The stars in the Southern CrossNorthern HemisphereIt's out of sight."The first man" refers to the first Christian, because inChristianismOfJerusalemJust can see the cross.Dante clearly realized thatprecession of the equinoxesHe mentioned a godless era after the death of Christ, when the Southern Cross had gradually disappeared in this latitude.The Southern Cross is not regarded as a cross in all culturesAustraliaThe stars in the middle are called "Eagle's Claw".
