1.
Sunspot
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Sunspots are temporary phenomena on the photosphere of the Sun that appear as dark spots compared with surrounding regions. They are areas of reduced surface temperature caused by concentrations of field flux that inhibit convection. Sunspots usually appear in pairs of magnetic polarity. Their number varies according to the approximately 11-year solar cycle, individual sunspots may endure anywhere from a few days to a few months, but eventually decay. Sunspots expand and contract as they move across the surface of the Sun with sizes ranging from 16 kilometers to 160,000 kilometers in diameter, the larger variety are visible from Earth without the aid of a telescope. They may travel at speeds, or proper motions of a few hundred meters per second when they first emerge. Indicating intense magnetic activity, sunspots accompany secondary phenomena such as coronal loops, most solar flares and coronal mass ejections originate in magnetically active regions around visible sunspot groupings. Similar phenomena indirectly observed on other than the sun are commonly called starspots. Although they are at temperatures of roughly 3, 000–4,500 K, isolated from the surrounding photosphere a sunspot would be brighter than the Moon. If the stress on the tubes reaches a limit, they curl up. Convection is inhibited at the points, the energy flux from the Suns interior decreases. The Wilson effect implies that sunspots are depressions on the Suns surface, observations using the Zeeman effect show that prototypical sunspots come in pairs with opposite magnetic polarity. From cycle to cycle, the polarities of leading and trailing sunspots change from north/south to south/north, magnetic pressure should tend to remove field concentrations, causing the sunspots to disperse, but sunspot lifetimes are measured in days to weeks. Sunspot activity cycles about every eleven years, the point of highest sunspot activity during a cycle is known as solar maximum, and the point of lowest activity as solar minimum. This period is observed in most other solar activity and is linked to a variation in the solar magnetic field that changes polarity with this period. Early in the cycle, sunspots appear in the latitudes and then move towards the equator as the cycle approaches maximum. Spots from two adjacent cycles can co-exist for some time, spots from adjacent cycles can be distinguished by direction of their magnetic field. The Wolf number sunspot index counts the number of sunspots
2.
Science and technology of the Han dynasty
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There were great innovations in metallurgy. Smelting techniques were enhanced with inventions such as the waterwheel-powered bellows, the quality of life was improved with many Han inventions. The Han Chinese had hempen-bound bamboo scrolls to write on, yet by the 2nd century AD had invented the process which created a writing medium that was both cheap and easy to produce. The invention of the aided in the hauling of heavy loads. The maritime junk ship and stern-mounted steering rudder enabled the Chinese to venture out of waters of interior lakes and rivers. The invention of the reference for maps and raised-relief map allowed the Chinese to better navigate their terrain. In medicine, they used new herbal remedies to cure illnesses, calisthenics to keep physically fit, authorities in the capital were warned ahead of time of the direction of sudden earthquakes with the invention of the seismometer that was tripped by a vibration-sensitive pendulum device. To mark the passing of the seasons and special occasions, the Han Chinese used two variations of the calendar, which were established due to efforts in astronomy and mathematics. Hundreds of new roads and canals were built to transport, commerce, tax collection, communication. The Han-era Chinese also employed several types of bridges to cross waterways and deep gorges, such as bridges, arch bridges, simple suspension bridges. Han ruins of defensive city walls made of brick or rammed earth still stand today, if Mohism, rich in scientific thought, had rapidly grown and strengthened, the situation might have been very favorable to the development of a scientific structure. However, this did not happen because the seeds of the structure of science were never formed. During the late Eastern Han, disastrous upheavals again occurred in the process of social transformation, one can imagine the effect of this calamity on science. The most common writing mediums found in archaeological digs from ancient sites predating the Han period are shells, the written characters on these narrow flat strips of bamboo were arranged into vertical columns. Yet Chinese hempen paper of the Western Han and early Eastern Han eras was of a coarse quality, by the 3rd century, paper became one of Chinas chief writing mediums. The Han ceramics industry was upheld by private businesses as well as government agencies. Ceramics were used in domestic wares and utensils as well as materials for roof tiles. Kilns of the Han dynasty making grey pottery were able to reach firing temperatures above 1,000 °C, however, hard southern Chinese pottery made from a dense adhesive clay native only in the south was fired at even higher temperatures than grey pottery during the Han
3.
Han dynasty
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The Han dynasty was the second imperial dynasty of China, preceded by the Qin dynasty and succeeded by the Three Kingdoms period. Spanning over four centuries, the Han period is considered an age in Chinese history. To this day, Chinas majority ethnic group refers to itself as the Han people and it was founded by the rebel leader Liu Bang, known posthumously as Emperor Gaozu of Han, and briefly interrupted by the Xin dynasty of the former regent Wang Mang. This interregnum separates the Han dynasty into two periods, the Western Han or Former Han and the Eastern Han or Later Han, the emperor was at the pinnacle of Han society. He presided over the Han government but shared power with both the nobility and appointed ministers who came largely from the gentry class. The Han Empire was divided into areas controlled by the central government using an innovation inherited from the Qin known as commanderies. These kingdoms gradually lost all vestiges of their independence, particularly following the Rebellion of the Seven States, from the reign of Emperor Wu onward, the Chinese court officially sponsored Confucianism in education and court politics, synthesized with the cosmology of later scholars such as Dong Zhongshu. This policy endured until the fall of the Qing dynasty in 1911 AD, the Han dynasty was an age of economic prosperity and saw a significant growth of the money economy first established during the Zhou dynasty. The coinage issued by the government mint in 119 BC remained the standard coinage of China until the Tang dynasty. The period saw a number of limited institutional innovations, the Xiongnu, a nomadic steppe confederation, defeated the Han in 200 BC and forced the Han to submit as a de facto inferior partner, but continued their raids on the Han borders. Emperor Wu of Han launched several campaigns against them. The ultimate Han victory in these wars eventually forced the Xiongnu to accept vassal status as Han tributaries, the territories north of Hans borders were quickly overrun by the nomadic Xianbei confederation. Imperial authority was seriously challenged by large Daoist religious societies which instigated the Yellow Turban Rebellion. When Cao Pi, King of Wei, usurped the throne from Emperor Xian, following Liu Bangs victory in the Chu–Han Contention, the resulting Han dynasty was named after the Hanzhong fief. Chinas first imperial dynasty was the Qin dynasty, the Qin unified the Chinese Warring States by conquest, but their empire became unstable after the death of the first emperor Qin Shi Huangdi. Within four years, the authority had collapsed in the face of rebellion. Although Xiang Yu proved to be a commander, Liu Bang defeated him at Battle of Gaixia. Liu Bang assumed the title emperor at the urging of his followers and is known posthumously as Emperor Gaozu, Changan was chosen as the new capital of the reunified empire under Han
4.
Chinese astronomy
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Astronomy in China has a very long history, with historians indicating that the Chinese were the most persistent and accurate observers of celestial phenomena anywhere in the world before the Arabs. Detailed records of observations began during the Warring States period. The telescope was introduced in the seventeenth century, in 1669, the Peking observatory was completely redesigned and refitted under the direction of Ferdinand Verbiest. Today, China continues to be active in astronomy, with many observatories, one of the main functions was for the purpose of timekeeping. The Chinese used a calendar, but, because the cycles of the sun. The Chinese calendar was considered to be a symbol of a dynasty, as dynasties would rise and fall, astronomers and astrologers of each period would often prepare a new calendar to be made, with observations for that purpose. Astrological divination was also an important part of astronomy, astronomers took careful note of guest stars, which suddenly appeared among the fixed stars. Ancient astronomical records of phenomena like comets and supernovae are used in modern astronomical studies. The Chinese developed three different cosmological models, the Gai Tian, or hemispherical dome, model conceived the heavens as a hemisphere lying over a dome-shaped earth. The second cosmological model, associated with the Hun Tian school, saw the heavens as a celestial sphere not unlike the spherical models developed in the Greek, the divisions of the sky began with the Northern Dipper and the 28 mansions. In 1977, a box was excavated from the tomb of Yi. Names of the 28 lunar mansions were found on the cover of the box, as lunar mansions have such an ancient origin, the meanings of most of their names have become obscure. Even worse, the name of each lunar mansion consists of only one Chinese word, the meanings of the names are still under discussion. Besides the 28 lunar mansions, most constellations are based on the works of Shi Shen-fu and Gan De, in the fourth century BC, the two Chinese astronomers responsible for the earliest information going into the star catalogues were Shi Shen and Gan De of the Warring States period. These books appeared to have lasted until the sixth century, but were lost after that, a number of books share similar names, often quoted and named after them. These texts should not be confused with the original written by them. Notable works that helped preserve the contents include, Wu Xian has been one of the astronomers in debate and he is often represented as one of the Three Schools Astronomical tradition along with Gan and Shi. Moreover, it was customary in the past for the Chinese to forge works of notable scholars, Wu Xian is generally mentioned as the astronomer who lived many years before Gan and Shi
5.
Titus
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Titus was Roman emperor from 79 to 81. A member of the Flavian dynasty, Titus succeeded his father Vespasian upon his death, prior to becoming Emperor, Titus gained renown as a military commander, serving under his father in Judea during the First Jewish–Roman War. The campaign came to a halt with the death of emperor Nero in 68. When Vespasian was declared Emperor on 1 July 69, Titus was left in charge of ending the Jewish rebellion, in 70, he besieged and captured Jerusalem, and destroyed the city and the Second Temple. For this achievement Titus was awarded a triumph, the Arch of Titus commemorates his victory to this day. Under the rule of his father, Titus gained notoriety in Rome serving as prefect of the Praetorian Guard, despite concerns over his character, Titus ruled to great acclaim following the death of Vespasian in 79, and was considered a good emperor by Suetonius and other contemporary historians. As emperor, he is best known for completing the Colosseum, after barely two years in office, Titus died of a fever on 13 September 81. He was deified by the Roman Senate and succeeded by his younger brother Domitian, Titus was born in Rome, probably on 30 December 39 AD, as the eldest son of Titus Flavius Vespasianus—commonly known as Vespasian—and Domitilla the Elder. He had one sister, Domitilla the Younger, and one younger brother, Titus Flavius Domitianus. One such family was the gens Flavia, which rose from obscurity to prominence in just four generations, acquiring wealth. Tituss great-grandfather, Titus Flavius Petro, had served as a centurion under Pompey during Caesars civil war and his military career ended in disgrace when he fled the battlefield at the Battle of Pharsalus in 48 BC. Nevertheless, Petro managed to improve his status by marrying the extremely wealthy Tertulla, whose fortune guaranteed the upwards mobility of Petros son Titus Flavius Sabinus I, Sabinus himself amassed further wealth and possible equestrian status through his services as tax collector in Asia and banker in Helvetia. By marrying Vespasia Polla he allied himself to the prestigious patrician gens Vespasia, ensuring the elevation of his sons Titus Flavius Sabinus II. The political career of Vespasian included the offices of quaestor, aedile and praetor, and culminated with a consulship in 51, as a military commander, he gained early renown by participating in the Roman invasion of Britain in 43. The story was told that Titus was reclining next to Britannicus, the night he was murdered. Further details on his education are scarce, but it seems he showed promise in the military arts and was a skilled poet. From c.57 to 59 he was a tribune in Germania. He also served in Britannia, perhaps arriving c.60 with reinforcements needed after the revolt of Boudica, in c.63 he returned to Rome and married Arrecina Tertulla, daughter of a former Prefect of the Praetorian Guard
6.
Jerusalem
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Jerusalem is a city located on a plateau in the Judaean Mountains between the Mediterranean and the Dead Sea. It is considered a city in the three major Abrahamic religions of Judaism, Christianity and Islam. During its long history, Jerusalem has been destroyed at least twice, besieged 23 times, attacked 52 times, the part of Jerusalem called the City of David was settled in the 4th millennium BCE. In 1538, walls were built around Jerusalem under Suleiman the Magnificent, today those walls define the Old City, which has been traditionally divided into four quarters—known since the early 19th century as the Armenian, Christian, Jewish, and Muslim Quarters. The Old City became a World Heritage Site in 1981, and is on the List of World Heritage in Danger, Modern Jerusalem has grown far beyond the Old Citys boundaries. These foundational events, straddling the dawn of the 1st millennium BCE, the sobriquet of holy city was probably attached to Jerusalem in post-exilic times. The holiness of Jerusalem in Christianity, conserved in the Septuagint which Christians adopted as their own authority, was reinforced by the New Testament account of Jesuss crucifixion there, in Sunni Islam, Jerusalem is the third-holiest city, after Mecca and Medina. As a result, despite having an area of only 0, outside the Old City stands the Garden Tomb. Today, the status of Jerusalem remains one of the issues in the Israeli–Palestinian conflict. During the 1948 Arab–Israeli War, West Jerusalem was among the captured and later annexed by Israel while East Jerusalem, including the Old City, was captured. Israel captured East Jerusalem from Jordan during the 1967 Six-Day War and subsequently annexed it into Jerusalem, one of Israels Basic Laws, the 1980 Jerusalem Law, refers to Jerusalem as the countrys undivided capital. All branches of the Israeli government are located in Jerusalem, including the Knesset, the residences of the Prime Minister and President, the international community does not recognize Jerusalem as Israels capital, and the city hosts no foreign embassies. Jerusalem is also home to some non-governmental Israeli institutions of importance, such as the Hebrew University. In 2011, Jerusalem had a population of 801,000, of which Jews comprised 497,000, Muslims 281,000, a city called Rušalim in the Execration texts of the Middle Kingdom of Egypt is widely, but not universally, identified as Jerusalem. Jerusalem is called Urušalim in the Amarna letters of Abdi-Heba, the name Jerusalem is variously etymologized to mean foundation of the god Shalem, the god Shalem was thus the original tutelary deity of the Bronze Age city. The form Yerushalem or Yerushalayim first appears in the Bible, in the Book of Joshua, according to a Midrash, the name is a combination of Yhwh Yireh and the town Shalem. The earliest extra-biblical Hebrew writing of the word Jerusalem is dated to the sixth or seventh century BCE and was discovered in Khirbet Beit Lei near Beit Guvrin in 1961. The inscription states, I am Yahweh thy God, I will accept the cities of Judah and I will redeem Jerusalem, or as other scholars suggest, the mountains of Judah belong to him, to the God of Jerusalem
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