Planets, Great Wall, and Solar Eclipse (APOD 2009 July 18)

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neufer
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Planets, Great Wall, and Solar Eclipse (APOD 2009 July 18)

Post by neufer » Sat Jul 18, 2009 4:52 am

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http://apod.nasa.gov/apod/ap090718.html
http://tinyurl.com/lfsy26 wrote:
The Story About Two Chinese Astronomers Who Failed to Predict an Eclipse of the Sun
Posted: Nov 22nd, 2008

<<A frequently recounted Chinese story says that Hsi and Ho, the court astronomers, got drunk and neglected their duties so that they failed to predict an eclipse of the Sun. For this, the emperor had them executed. So much for negligent astronomers.

If this story were an account of an actual event, the dynasty mentioned would place the eclipse somewhere between 2159 and 1948 B.C., making it by far the oldest solar eclipse recorded in history. But all serious attempts to identify one particular eclipse as the source of this story have been abandoned as scholars have recognized that the episode is mythological.

In ancient Chinese literature, Hsi-Ho is not two persons but a single mythological being
who is sometimes the mother of the Sun and at other times the chariot driver for the Sun:
Image

Later, in the Shu Ching (Historical Classic), parts of which may date from as early as the seventh or sixth century B.C., this single character is split, not into two, but into six.

In the Shu Ching story, the legendary Chinese emperor Yao commissions the eldest of the Hsi and Ho brothers "to calculate and delineate the sun, moon, the stars, and the zodiacal markers; and so to deliver respectfully the seasons to the people." In further orders, he sends a younger Hsi brother to the east and another to the south; he orders a younger Ho brother to the west and another to the north. Each is responsible for a portion of the rhythms of the days and seasons, to turn the Sun back at the solstices and to keep it moving at the equinoxes.

These mythological magicians are always charged with the prevention of eclipses, hence the story that appears later in the Shu Ching about the emperor's anger with his servants for failing to prevent an eclipse, not just predict or respond ceremonially to it. The story appears in a chapter that is an exhortation by the Prince of Yin, commander of the armies, to government officials to fulfill their duties to the administration, thereby making the emperor "entirely intelligent. "If anyone neglects this requirement, "the country has regular punishments for you."

Now here are Hsi and Ho. They have entirely subverted their virtue, and are sunk and lost in wine. They have violated the duties of their office, and left their posts. They have been the first to allow the regulations of heaven to get into disorder, putting far from them their proper business. On the first day of the last month of autumn, the sun and moon did not meet harmoniously in Fang.

The blind musicians beat their drums; the inferior officers and common people bustled and ran about. Hsi and Ho, however, as if they were mere personators of the dead in their offices, heard nothing and knew nothing; so stupidly went they astray from their duty in the matter of the heavenly appearances, and rendering themselves liable to the death appointed by the former kings. The statutes of government say, "When they anticipate the time, let them be put to death without mercy; when they are behind the time, let them be put to death without mercy. We never hear whether Hsi and Ho were ever tracked down and executed.>>
Art Neuendorffer

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neufer
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Re: Planets, Great Wall, and Solar Eclipse (APOD 2009 July 1

Post by neufer » Sat Jul 18, 2009 1:06 pm

http://antwrp.gsfc.nasa.gov/apod/ap071107.html wrote:
The Sloan Great Wall: Largest Known Structure?

Explanation: What is the largest structure known? The answer might depend on how one defines "structure." A grouping of galaxies known as the Sloan Great Wall was discovered in the Sloan Digital Sky Survey and is a leading candidate. The Sloan Great Wall can be seen in this digitally recast contour map of galaxies in the Two Degree Field galaxy survey. Galaxies within one billion light years, a redshift of about 0.1, are depicted. The labeled Sloan Great Wall spans over one billion light years, longer than any structure ever measured. Critics worry that the Sloan Great Wall should not itself be characterized as a coherent structure because it is not currently gravitationally bound together and parts of it might never become gravitationally bound. Regardless, the beauty of the local universe of galaxies is evident in the image where several huge superclusters of galaxies -- clusters of galaxy clusters -- can also be seen. These include the Shapley Supercluster of galaxies, part of the Pisces-Cetus Supercluster, and part of the Horologium-Reticulum Supercluster.
Art Neuendorffer

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