Misplaced Pages

#442557

163-457: Sirius is the brightest star in the night sky . Its name is derived from the Greek word Σείριος (Latin script: Seirios ), meaning lit. 'glowing' or 'scorching'. The star is designated α  Canis Majoris , Latinized to Alpha Canis Majoris , and abbreviated α  CMa or Alpha CMa . With a visual apparent magnitude of −1.46, Sirius is almost twice as bright as Canopus ,

326-629: A ceramic glaze known as faience , which was used well into the Roman Period to decorate cups, amulets, and figurines. During the last predynastic phase, the Naqada culture began using written symbols that eventually were developed into a full system of hieroglyphs for writing the ancient Egyptian language. The Early Dynastic Period was approximately contemporary to the early Sumerian - Akkadian civilization of Mesopotamia and of ancient Elam . The third-century   BC Egyptian priest Manetho grouped

489-469: A corvée system. Artists and craftsmen were of higher status than farmers, but they were also under state control, working in the shops attached to the temples and paid directly from the state treasury. Scribes and officials formed the upper class in ancient Egypt, known as the "white kilt class" in reference to the bleached linen garments that served as a mark of their rank. The upper class prominently displayed their social status in art and literature. Below

652-417: A nomarch , who was accountable to the vizier for his jurisdiction. The temples formed the backbone of the economy. Not only were they places of worship , but were also responsible for collecting and storing the kingdom's wealth in a system of granaries and treasuries administered by overseers , who redistributed grain and goods. Much of the economy was centrally organized and strictly controlled. Although

815-444: A balanced relationship between people and animals was an essential element of the cosmic order; thus humans, animals and plants were believed to be members of a single whole. Animals, both domesticated and wild , were therefore a critical source of spirituality, companionship, and sustenance to the ancient Egyptians. Cattle were the most important livestock; the administration collected taxes on livestock in regular censuses , and

978-591: A brief but spirited resurgence in the economy and culture, but in 525   BC, the Persian Empire, led by Cambyses II , began its conquest of Egypt, eventually defeating the pharaoh Psamtik III at the Battle of Pelusium . Cambyses II then assumed the formal title of pharaoh, but ruled Egypt from Iran, leaving Egypt under the control of a satrap . A few revolts against the Persians marked the 5th century   BC, but Egypt

1141-556: A bright giant). It is still around 25 times more luminous than the Sun. The closest large neighbouring star to Sirius is Procyon, 1.61 parsecs (5.24 ly) away. The Voyager 2 spacecraft, launched in 1977 to study the four giant planets in the Solar System, is expected to pass within 4.3 light-years (1.3 pc) of Sirius in approximately 296,000 years. Sirius is a binary star system consisting of two white stars orbiting each other with

1304-694: A confident, eloquent style. The relief and portrait sculpture of the period captured subtle, individual details that reached new heights of technical sophistication. The last great ruler of the Middle Kingdom, Amenemhat III , allowed Semitic -speaking Canaanite settlers from the Near East into the Delta region to provide a sufficient labor force for his especially active mining and building campaigns. These ambitious building and mining activities, however, combined with severe Nile floods later in his reign, strained

1467-530: A cornerstone in the history of human civilization. Nomadic modern human hunter-gatherers began living in the Nile valley through the end of the Middle Pleistocene some 120,000 years ago. By the late Paleolithic period, the arid climate of Northern Africa had become increasingly hot and dry, forcing the populations of the area to concentrate along the river region. In Predynastic and Early Dynastic times,

1630-463: A distance of 2.6 parsecs (8.6 ly), the Sirius system contains two of the eight nearest stars to the Sun, and it is the fifth closest stellar system to the Sun. This proximity is the main reason for its brightness, as with other near stars such as Alpha Centauri , Procyon and Vega and in contrast to distant, highly luminous supergiants such as Canopus, Rigel or Betelgeuse (although Canopus may be

1793-408: A final summary in 1926. He cited not only Ptolemy but also the poet Aratus , the orator Cicero , and general Germanicus all calling the star red, though acknowledging that none of the latter three authors were astronomers, the last two merely translating Aratus's poem Phaenomena . Seneca had described Sirius as being of a deeper red than Mars . It is therefore possible that the description as red

SECTION 10

#1732845515443

1956-566: A large-scale building campaign to promote the god Amun , whose growing cult was based in Karnak . They also constructed monuments to glorify their own achievements, both real and imagined. The Karnak temple is the largest Egyptian temple ever built. Around 1350   BC, the stability of the New Kingdom was threatened when Amenhotep IV ascended the throne and instituted a series of radical and chaotic reforms. Changing his name to Akhenaten , he touted

2119-468: A list which compensates for the distances, converting the apparent magnitude to the absolute magnitude , see the list of most luminous stars . The Sun is the brightest star as viewed from Earth , at −26.78 mag. The second brightest is Sirius at −1.46 mag. For comparison, the brightest non-stellar objects in the Solar System have maximum brightnesses of: Any exact order of

2282-583: A little-attested Greek myth, the star-god that personified Sirius fell in love with a fertility goddess named Opora , but he was unable to have her. Thus he began to burn hot, making humans suffer, who prayed to the gods. The god of the north wind, Boreas , solved the problem by ordering his sons to deliver Opora to Sirius, while he cooled down the earth with blasts of his own cold wind. In Iranian mythology, especially in Persian mythology and in Zoroastrianism ,

2445-507: A paper and spoke at a meeting of the Royal Society in London in 1760. The existence of other stars changing in brightness gave credibility to the idea that some may change in colour too; Sir John Herschel noted this in 1839, possibly influenced by witnessing Eta Carinae two years earlier. Thomas J.J. See resurrected discussion on red Sirius with the publication of several papers in 1892, and

2608-403: A parallax of nearly 0.4 arcseconds . The Hipparcos parallax for Sirius is only accurate to about ± 0.04  light years , giving a distance of 8.6 light years . Sirius B is generally assumed to be at the same distance. Sirius B has a Gaia Data Release 3 parallax with a much smaller statistical margin of error, giving a distance of 8.709 ± 0.005 light years , but it

2771-557: A period of almost exactly 365.25 days holding it constant relative to the solar year . This rising occurs at Cairo on 19 July ( Julian ), placing it just before the onset of the annual flooding of the Nile during antiquity. Owing to the flood's own irregularity, the extreme precision of the star's return made it important to the ancient Egyptians , who worshipped it as the goddess Sopdet ( Ancient Egyptian : Spdt , "Triangle"; Ancient Greek : Σῶθις }, Sō̂this ), guarantor of

2934-562: A period of economic and cultural renaissance known as the Middle Kingdom . The kings of the Middle Kingdom restored the country's stability and prosperity, thereby stimulating a resurgence of art, literature, and monumental building projects. Mentuhotep II and his Eleventh Dynasty successors ruled from Thebes, but the vizier Amenemhat I , upon assuming the kingship at the beginning of the Twelfth Dynasty around 1985   BC, shifted

3097-502: A piece of papyrus or an ostracon . A combination of favorable geographical features contributed to the success of ancient Egyptian culture, the most important of which was the rich fertile soil resulting from annual inundations of the Nile River. The ancient Egyptians were thus able to produce an abundance of food, allowing the population to devote more time and resources to cultural, technological, and artistic pursuits. Land management

3260-670: A queen who established herself as pharaoh, launched many building projects, including the restoration of temples damaged by the Hyksos, and sent trading expeditions to Punt and the Sinai. When Tuthmosis III died in 1425   BC, Egypt had an empire extending from Niya in north west Syria to the Fourth Cataract of the Nile in Nubia , cementing loyalties and opening access to critical imports such as bronze and wood . The New Kingdom pharaohs began

3423-410: A real change in the Sirius system over the past two millennia, of which the most widely discussed is the proposal that the white dwarf Sirius B was a red giant as recently as 2000 years ago. Extrinsic theories are concerned with the possibility of transient reddening in an intervening medium through which the star is observed, such as might be caused by dust in the interstellar medium , or by particles in

SECTION 20

#1732845515443

3586-591: A rival dynasty in the delta arose in Leontopolis , and Kushites threatened from the south. Around 727   BC the Kushite king Piye invaded northward, seizing control of Thebes and eventually the Delta, which established the 25th Dynasty . During the 25th Dynasty, Pharaoh Taharqa created an empire nearly as large as the New Kingdom 's. Twenty-fifth Dynasty pharaohs built, or restored, temples and monuments throughout

3749-437: A separation of about 20 AU (roughly the distance between the Sun and Uranus ) and a period of 50.1 years. The brighter component, termed Sirius A, is a main-sequence star of spectral type early A , with an estimated surface temperature of 9,940  K . Its companion, Sirius B, is a star that has already evolved off the main sequence and become a white dwarf. Currently 10,000 times less luminous in

3912-638: A series of vassals who became known as the Saite kings of the Twenty-Sixth Dynasty . By 653   BC, the Saite king Psamtik I was able to oust the Assyrians with the help of Greek mercenaries, who were recruited to form Egypt's first navy . Greek influence expanded greatly as the city-state of Naucratis became the home of Greeks in the Nile Delta. The Saite kings based in the new capital of Sais witnessed

4075-427: A third star or a planet. An apparent "third star" observed in the 1920s is now believed to be a background object. In 1915, Walter Sydney Adams , using a 60-inch (1.5 m) reflector at Mount Wilson Observatory , observed the spectrum of Sirius B and determined that it was a faint whitish star. This led astronomers to conclude that it was a white dwarf—the second to be discovered. The diameter of Sirius A

4238-400: A third star sufficiently luminous to affect the visible colour of the system in recent millennia is inconsistent with observational evidence. Intrinsic theories may therefore be disregarded. Extrinsic theories based on reddening by interstellar dust are similarly implausible. A transient dust cloud passing between the Sirius system and an observer on Earth would, indeed redden the appearance of

4401-454: Is 25,200 K. Because there is no internal heat source, Sirius B will steadily cool as the remaining heat is radiated into space over the next two billion years or so. A white dwarf forms after a star has evolved from the main sequence and then passed through a red giant stage. This occurred when Sirius B was less than half its current age, around 120 million years ago. The original star had an estimated 5  M ☉ and

4564-458: Is a divinity of rain and fertility and an antagonist of apaosha , the demon of drought. In this struggle, Tishtrya is depicted as a white horse. In Chinese astronomy Sirius is known as the star of the "celestial wolf" ( Chinese and Japanese : 天狼 Chinese romanization : Tiānláng; Japanese romanization : Tenrō; Korean and romanization: 천랑 /Cheonrang) in the Mansion of Jǐng (井宿). Many nations among

4727-401: Is a poetic metaphor for ill fortune. In 1985, German astronomers Wolfhard Schlosser and Werner Bergmann published an account of an 8th-century Lombardic manuscript, which contains De cursu stellarum ratio by St.  Gregory of Tours . The Latin text taught readers how to determine the times of nighttime prayers from positions of the stars, and a bright star described as rubeola ("reddish")

4890-478: Is a relatively low 16 km/s, which does not produce any significant flattening of its disk. This is at marked variance with the similar-sized Vega , which rotates at a much faster 274 km/s and bulges prominently around its equator. A weak magnetic field has been detected on the surface of Sirius A. Stellar models suggest that the star formed during the collapsing of a molecular cloud and that, after 10 million years, its internal energy generation

5053-556: Is between 200 and 300 million years old. It was originally composed of two bright bluish stars. The initially more massive of these, Sirius B, consumed its hydrogen fuel and became a red giant before shedding its outer layers and collapsing into its current state as a white dwarf around 120 million years ago. Sirius is colloquially known as the " Dog Star ", reflecting its prominence in its constellation , Canis Major (the Greater Dog). The heliacal rising of Sirius marked

Sirius - Misplaced Pages Continue

5216-472: Is classed as a type Am star , because the spectrum shows deep metallic absorption lines , indicating an enhancement of its surface layers in elements heavier than helium, such as iron. The spectral type has been reported as A0mA1 Va, which indicates that it would be classified as A1 from hydrogen and helium lines, but A0 from the metallic lines that cause it to be grouped with the Am ;stars. When compared to

5379-629: Is depicted at the Temple of Hathor in Dendera , where the goddess Satet has drawn her arrow at Hathor (Sirius). Known as "Tir", the star was portrayed as the arrow itself in later Persian culture. Sirius is mentioned in Surah , An-Najm ("The Star"), of the Qur'an , where it is given the name الشِّعْرَى (transliteration: aš-ši'rā or ash-shira ; the leader). The verse is: " وأنَّهُ هُوَ رَبُّ الشِّعْرَى ", "That He

5542-448: Is flagged as having a very large value for astrometric excess noise, which indicates that the parallax value may be unreliable. In a letter dated 10 August 1844, the German astronomer Friedrich Wilhelm Bessel deduced from changes in the proper motion of Sirius that it had an unseen companion. On 31 January 1862, American telescope-maker and astronomer Alvan Graham Clark first observed

5705-515: Is now sometimes known as Sirius A. Since 1894, some apparent orbital irregularities in the Sirius system have been observed, suggesting a third very small companion star, but this has never been confirmed. The best fit to the data indicates a six-year orbit around Sirius A and a mass of 0.06  M ☉ . This star would be five to ten magnitudes fainter than the white dwarf Sirius B, which would make it difficult to observe. Observations published in 2008 were unable to detect either

5868-408: Is often colloquially called the "Dog Star" as the brightest star of Canis Major , the "Great Dog" constellation. Canis Major was classically depicted as Orion 's dog. The Ancient Greeks thought that Sirius's emanations could affect dogs adversely, making them behave abnormally during the "dog days", the hottest days of the summer. The Romans knew these days as dies caniculares , and the star Sirius

6031-731: Is the Lord of Sirius (the Mighty Star)." (An-Najm:49) Ibn Kathir said in his commentary "that it is the bright star, named Mirzam Al-Jawza' (Sirius), which a group of Arabs used to worship". The alternate name Aschere , used by Johann Bayer , is derived from this. In theosophy , it is believed the Seven Stars of the Pleiades transmit the spiritual energy of the Seven Rays from the Galactic Logos to

6194-469: Is visible from almost everywhere on Earth, except latitudes north of 73° N , and it does not rise very high when viewed from some northern cities (reaching only 13° above the horizon from Saint Petersburg ). Because of its declination of roughly −17°, Sirius is a circumpolar star from latitudes south of 73° S . From the Southern Hemisphere in early July, Sirius can be seen in both

6357-567: The Amarna Period . Around 1279   BC, Ramesses II , also known as Ramesses the Great, ascended the throne, and went on to build more temples, erect more statues and obelisks, and sire more children than any other pharaoh in history. A bold military leader, Ramesses II led his army against the Hittites in the Battle of Kadesh (in modern Syria ) and, after fighting to a stalemate, finally agreed to

6520-505: The Cape of Good Hope (4 seconds); by Piazzi (the same amount); using Lacaille's observations made at Paris , more numerous and certain than those made at the Cape (no sensible parallax); by Bessel (no sensible parallax). Scottish astronomer Thomas Henderson used his observations made in 1832–1833 and South African astronomer Thomas Maclear 's observations made in 1836–1837, to determine that

6683-503: The Egyptian climate was much less arid than it is today . Large regions of Egypt were covered in treed savanna and traversed by herds of grazing ungulates . Foliage and fauna were far more prolific in all environs, and the Nile region supported large populations of waterfowl . Hunting would have been common for Egyptians, and this is also the period when many animals were first domesticated . By about 5500 BC , small tribes living in

Sirius - Misplaced Pages Continue

6846-495: The Great Kenbet , over which the vizier or pharaoh presided. Plaintiffs and defendants were expected to represent themselves and were required to swear an oath that they had told the truth. In some cases, the state took on both the role of prosecutor and judge, and it could torture the accused with beatings to obtain a confession and the names of any co-conspirators. Whether the charges were trivial or serious, court scribes documented

7009-511: The Hyades and the Pleiades , and each of these clusters consists of hundreds of stars. In 2017, a massive star cluster was discovered only 10  arcminutes from Sirius, making the two appear to be visually close to one other when viewed from the point of view of the Earth . It was discovered during a statistical analysis of Gaia data. The cluster is over a thousand times further away from us than

7172-666: The International Astronomical Union organized a Working Group on Star Names (WGSN) to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names approved by the WGSN, which included Sirius for the star α Canis Majoris A. It is now so entered in the IAU Catalog of Star Names. Sirius has over 50 other designations and names attached to it. In Geoffrey Chaucer 's essay Treatise on

7335-593: The Macedonians under Alexander the Great . The Greek Ptolemaic Kingdom , formed in the aftermath of Alexander's death, ruled until 30   BC, when, under Cleopatra , it fell to the Roman Empire and became a Roman province . Egypt remained under Roman control until 642 AD, when it was conquered by the Rashidun Caliphate . The success of ancient Egyptian civilization came partly from its ability to adapt to

7498-799: The Marquesas Islands , Rehua in New Zealand, and Ta'urua-fau-papa "Festivity of original high chiefs" and Ta'urua-e-hiti-i-te-tara-te-feiai "Festivity who rises with prayers and religious ceremonies" in Tahiti. In 1717, Edmond Halley discovered the proper motion of the hitherto presumed fixed stars after comparing contemporary astrometric measurements with those from the second century AD given in Ptolemy's Almagest . The bright stars Aldebaran , Arcturus and Sirius were noted to have moved significantly; Sirius had progressed about 30 arcminutes (about

7661-951: The Mouseion . The Lighthouse of Alexandria lit the way for the many ships that kept trade flowing through the city—as the Ptolemies made commerce and revenue-generating enterprises, such as papyrus manufacturing, their top priority. Hellenistic culture did not supplant native Egyptian culture, as the Ptolemies supported time-honored traditions in an effort to secure the loyalty of the populace. They built new temples in Egyptian style, supported traditional cults, and portrayed themselves as pharaohs. Some traditions merged, as Greek and Egyptian gods were syncretized into composite deities, such as Serapis , and classical Greek forms of sculpture influenced traditional Egyptian motifs. Despite their efforts to appease

7824-489: The Near East . The New Kingdom pharaohs established a period of unprecedented prosperity by securing their borders and strengthening diplomatic ties with their neighbours, including the Mitanni Empire, Assyria , and Canaan . Military campaigns waged under Tuthmosis I and his grandson Tuthmosis III extended the influence of the pharaohs to the largest empire Egypt had ever seen. Between their reigns, Hatshepsut ,

7987-738: The New Kingdom of the Late Bronze Age . Ancient Egypt reached the pinnacle of its power during the New Kingdom, ruling much of Nubia and a sizable portion of the Levant . After this period, it entered an era of slow decline. During the course of its history, ancient Egypt was invaded or conquered by a number of foreign powers, including the Hyksos , the Nubians , the Assyrians , the Achaemenid Persians , and

8150-534: The Nile . They also traded with Nubia to the south, the oases of the western desert to the west, and the cultures of the eastern Mediterranean and Near East to the east. The Naqada culture manufactured a diverse selection of material goods, reflective of the increasing power and wealth of the elite, as well as societal personal-use items, which included combs, small statuary, painted pottery, high quality decorative stone vases , cosmetic palettes , and jewelry made of gold, lapis, and ivory. They also developed

8313-463: The Nubians to the south of Egypt, but failed to defeat the Hyksos. That task fell to Kamose's successor, Ahmose I , who successfully waged a series of campaigns that permanently eradicated the Hyksos' presence in Egypt. He established a new dynasty and, in the New Kingdom that followed, the military became a central priority for the kings, who sought to expand Egypt's borders and attempted to gain mastery of

SECTION 50

#1732845515443

8476-584: The Persians and was welcomed by the Egyptians as a deliverer. The administration established by Alexander's successors, the Macedonian Ptolemaic Kingdom , was based on an Egyptian model and based in the new capital city of Alexandria . The city showcased the power and prestige of Hellenistic rule, and became a centre of learning and culture, that included the famous Library of Alexandria as part of

8639-654: The Seven Stars of the Great Bear , then to Sirius. From there is it sent via the Sun to the god of Earth ( Sanat Kumara ), and finally through the seven Masters of the Seven Rays to the human race. The midnight culmination of Sirius in the northern hemisphere coincides with the beginning of the New Year of the Gregorian calendar during the decades around the year 2000. Over the years, its midnight culmination moves slowly, owing to

8802-399: The Solar System . At a distance of 2.64 parsecs (8.6  ly ), the Sirius system is one of Earth's nearest neighbours . Sirius is gradually moving closer to the Solar System; it is expected to increase in brightness slightly over the next 60,000 years to reach a peak magnitude of −1.68. Coincidentally, at about the same time, Sirius will take its turn as the southern Pole Star, around

8965-600: The Thirtieth , proved to be the last native royal house of ancient Egypt, ending with the kingship of Nectanebo II . A brief restoration of Persian rule, sometimes known as the Thirty-First Dynasty , began in 343   BC, but shortly after, in 332   BC, the Persian ruler Mazaces handed Egypt over to Alexander the Great without a fight. In 332   BC, Alexander the Great conquered Egypt with little resistance from

9128-536: The Wadi Natrun for mummification , which also provided the gypsum needed to make plaster. Ore-bearing rock formations were found in distant, inhospitable wadis in the Eastern Desert and the Sinai, requiring large, state-controlled expeditions to obtain natural resources found there. There were extensive gold mines in Nubia , and one of the first maps known is of a gold mine in this region. The Wadi Hammamat

9291-451: The chaff from the grain, and the grain was then ground into flour, brewed to make beer, or stored for later use. The ancient Egyptians cultivated emmer and barley , and several other cereal grains, all of which were used to make the two main food staples of bread and beer. Flax plants, uprooted before they started flowering, were grown for the fibers of their stems. These fibers were split along their length and spun into thread, which

9454-568: The composite bow and the horse-drawn chariot . After retreating south, the native Theban kings found themselves trapped between the Canaanite Hyksos ruling the north and the Hyksos' Nubian allies, the Kushites , to the south. After years of vassalage, Thebes gathered enough strength to challenge the Hyksos in a conflict that lasted more than 30 years, until 1555   BC. The kings Seqenenre Tao II and Kamose were ultimately able to defeat

9617-453: The earliest known peace treaty , made with the Hittites . Ancient Egypt has left a lasting legacy. Its art and architecture were widely copied, and its antiquities were carried off to be studied, admired or coveted in the far corners of the world. Its monumental ruins have inspired the imaginations of travelers and writers for millennia. A newfound respect for antiquities and excavations in

9780-716: The flooding of the Nile in Ancient Egypt and the " dog days " of summer for the ancient Greeks , while to the Polynesians , mostly in the Southern Hemisphere, the star marked winter and was an important reference for their navigation around the Pacific Ocean. As the brightest star in the night sky, Sirius appears in some of the earliest astronomical records. Its displacement from the ecliptic causes its heliacal rising to be remarkably regular compared to other stars, with

9943-400: The terrestrial atmosphere . The possibility that stellar evolution of either Sirius A or Sirius B could be responsible for the discrepancy has been rejected on the grounds that the timescale of thousands of years is orders of magnitude too short and that there is no sign of the nebulosity in the system that would be expected had such a change taken place. Similarly, the presence of

SECTION 60

#1732845515443

10106-523: The vizier and his court for redress. Although slaves were mostly used as indentured servants, they were able to buy and sell their servitude, work their way to freedom or nobility, and were usually treated by doctors in the workplace. Both men and women had the right to own and sell property, make contracts, marry and divorce, receive inheritance, and pursue legal disputes in court. Married couples could own property jointly and protect themselves from divorce by agreeing to marriage contracts, which stipulated

10269-426: The "Wolf Star", while other branches knew it as the "Coyote Star". Further north, the Alaskan Inuit of the Bering Strait called it "Moon Dog". Several cultures also associated the star with a bow and arrows. The ancient Chinese visualized a large bow and arrow across the southern sky, formed by the constellations of Puppis and Canis Major. In this, the arrow tip is pointed at the wolf Sirius. A similar association

10432-440: The Assyrians. The effects of external threats were exacerbated by internal problems such as corruption, tomb robbery, and civil unrest . After regaining their power, the high priests at the temple of Amun in Thebes accumulated vast tracts of land and wealth, and their expanded power splintered the country during the Third Intermediate Period. Following the death of Ramesses XI in 1078   BC, Smendes assumed authority over

10595-426: The Astrolabe , it bears the name Alhabor and is depicted by a hound's head. This name is widely used on medieval astrolabes from Western Europe. In Sanskrit it is known as Mrgavyadha "deer hunter", or Lubdhaka "hunter". As Mrgavyadha, the star represents Rudra ( Shiva ). The star is referred to as Makarajyoti in Malayalam and has religious significance to the pilgrim center Sabarimala . In Scandinavia ,

10758-419: The Christian emperor Theodosius introduced legislation that banned pagan rites and closed temples. Alexandria became the scene of great anti-pagan riots with public and private religious imagery destroyed. As a consequence, Egypt's native religious culture was continually in decline. While the native population continued to speak their language , the ability to read hieroglyphic writing slowly disappeared as

10921-435: The Delta, seized control of Egypt and established their capital at Avaris , forcing the former central government to retreat to Thebes . The king was treated as a vassal and expected to pay tribute. The Hyksos ('foreign rulers') retained Egyptian models of government and identified as kings, thereby integrating Egyptian elements into their culture. They and other invaders introduced new tools of warfare into Egypt, most notably

11084-426: The Earth's atmosphere are better supported by available evidence. Scintillations caused by atmospheric turbulence result in rapid, transient changes in the apparent colour of the star, especially when observed near the horizon, although with no particular preference for red. However, systematic reddening of the star's light results from absorption and scattering by particles in the atmosphere, exactly analogous to

11247-481: The Earth's night sky for approximately the next 210,000 years, at which point Vega , another A-type star that is intrinsically more luminous than Sirius, becomes the brightest star. Sirius A is about twice as massive as the Sun ( M ☉ ) and has an absolute visual magnitude of +1.43. It is 25 times as luminous as the Sun , but has a significantly lower luminosity than other bright stars such as Canopus, Betelgeuse , or Rigel . The system

11410-401: The Egyptians, the Ptolemies were challenged by native rebellion, bitter family rivalries, and the powerful mob of Alexandria that formed after the death of Ptolemy IV . In addition, as Rome relied more heavily on imports of grain from Egypt, the Romans took great interest in the political situation in the country. Continued Egyptian revolts, ambitious politicians, and powerful opponents from

11573-451: The Greeks towards the Egyptians, some traditions such as mummification and worship of the traditional gods continued. The art of mummy portraiture flourished, and some Roman emperors had themselves depicted as pharaohs, though not to the extent that the Ptolemies had. The former lived outside Egypt and did not perform the ceremonial functions of Egyptian kingship. Local administration became Roman in style and closed to native Egyptians. From

11736-627: The Hubble Space Telescope ruled out the existence of a stellar mass sized Sirius C, while still allowing a substellar mass candidate such as a lower mass Brown dwarf . The 1995 study predicted an astrometric movement of roughly 90  mas (0.09 arcsecond), but Hubble was unable to detect any location anomaly to an accuracy of 5 mas (0.005 arcsec). This ruled out any objects orbiting Sirius A with more than 0.033 solar mass (35 Jupiter masses) in 0.5 years, and 0.014 (15 Jupiter masses) in 2 years. The study

11899-693: The IAU are omitted. The source of magnitudes cited in this list is the linked Misplaced Pages articles. This basic list is a catalog of what Misplaced Pages itself documents. References can be found in the individual articles. Ancient Egypt Ancient Egypt was a civilization of ancient Northeast Africa . It was concentrated along the lower reaches of the Nile River , situated within the contemporary territory of modern-day Egypt . Ancient Egyptian civilization followed prehistoric Egypt and coalesced around 3100   BC (according to conventional Egyptian chronology ) with

12062-539: The Late Period, the worship of the gods in their animal form was extremely popular, such as the cat goddess Bastet and the ibis god Thoth , and these animals were kept in large numbers for the purpose of ritual sacrifice. Egypt is rich in building and decorative stone, copper and lead ores, gold, and semiprecious stones. These natural resources allowed the ancient Egyptians to build monuments, sculpt statues, make tools, and fashion jewelry . Embalmers used salts from

12225-452: The Late Period. There is also evidence to suggest that elephants were briefly used in the Late Period but largely abandoned due to lack of grazing land. Cats , dogs, and monkeys were common family pets, while more exotic pets imported from the heart of Africa, such as Sub-Saharan African lions , were reserved for royalty. Herodotus observed that the Egyptians were the only people to keep their animals with them in their houses. During

12388-516: The Near East made this situation unstable, leading Rome to send forces to secure the country as a province of its empire. Egypt became a province of the Roman Empire in 30   BC, following the defeat of Mark Antony and Ptolemaic Queen Cleopatra VII by Octavian (later Emperor Augustus) in the Battle of Actium . The Romans relied heavily on grain shipments from Egypt, and the Roman army , under

12551-557: The Nile valley had developed into a series of cultures demonstrating firm control of agriculture and animal husbandry , and identifiable by their pottery and personal items, such as combs, bracelets, and beads. The largest of these early cultures in upper (Southern) Egypt was the Badarian culture , which probably originated in the Western Desert ; it was known for its high-quality ceramics, stone tools , and its use of copper. The Badari

12714-537: The Nile valley, including at Memphis, Karnak, Kawa, and Jebel Barkal. During this period, the Nile valley saw the first widespread construction of pyramids (many in modern Sudan) since the Middle Kingdom. Egypt's far-reaching prestige declined considerably toward the end of the Third Intermediate Period. Its foreign allies had fallen under the Assyrian sphere of influence, and by 700   BC war between

12877-565: The Old Kingdom, and provided both honey and wax. The ancient Egyptians used donkeys and oxen as beasts of burden , and they were responsible for plowing the fields and trampling seed into the soil. The slaughter of a fattened ox was also a central part of an offering ritual. Horses were introduced by the Hyksos in the Second Intermediate Period . Camels, although known from the New Kingdom, were not used as beasts of burden until

13040-405: The Old Kingdom. Under the direction of the vizier , state officials collected taxes, coordinated irrigation projects to improve crop yield , drafted peasants to work on construction projects, and established a justice system to maintain peace and order. With the rising importance of central administration in Egypt, a new class of educated scribes and officials arose who were granted estates by

13203-630: The Polynesian night sky into two hemispheres. Just as the appearance of Sirius in the morning sky marked summer in Greece, it marked the onset of winter for the Māori , whose name Takurua described both the star and the season. Its culmination at the winter solstice was marked by celebration in Hawaii , where it was known as Ka'ulua , "Queen of Heaven". Many other Polynesian names have been recorded, including Tau-ua in

13366-618: The Roman period, mapped the stars in Books ;VII and VIII of his Almagest , in which he used Sirius as the location for the globe's central meridian. He described Sirius as reddish, along with five other stars, Betelgeuse , Antares , Aldebaran , Arcturus , and Pollux , all of which are at present observed to be of orange or red hue. The discrepancy was first noted by amateur astronomer Thomas Barker , squire of Lyndon Hall in Rutland , who prepared

13529-508: The Ruler ", to defend against foreign attack. With the kings having secured the country militarily and politically and with vast agricultural and mineral wealth at their disposal, the nation's population, arts, and religion flourished. In contrast to elitist Old Kingdom attitudes towards the gods, the Middle Kingdom displayed an increase in expressions of personal piety. Middle Kingdom literature featured sophisticated themes and characters written in

13692-411: The Sun's, has an age that is only half this, making it too young to belong to the group. Sirius may instead be a member of the proposed Sirius Supercluster, along with other scattered stars such as Beta Aurigae , Alpha Coronae Borealis , Beta Crateris , Beta Eridani and Beta Serpentis . This would be one of three large clusters located within 500 light-years (150 pc) of the Sun. The other two are

13855-418: The Sun, the proportion of iron in the atmosphere of Sirius A relative to hydrogen is given by   [ Fe H ] = 0.5   , {\displaystyle \textstyle \ \left[{\frac {{\ce {Fe}}}{{\ce {H}}}}\right]=0.5\ ,} meaning iron is 316% as abundant as in the Sun's atmosphere. The high surface content of metallic elements is unlikely to be true of

14018-499: The administration, aside from the royal high priestesses, apparently served only secondary roles in the temples (not much data for many dynasties), and were not so probably to be as educated as men. The head of the legal system was officially the pharaoh, who was responsible for enacting laws, delivering justice, and maintaining law and order, a concept the ancient Egyptians referred to as Ma'at . Although no legal codes from ancient Egypt survive, court documents show that Egyptian law

14181-409: The ancient Polynesians for navigation of the Pacific Ocean. They also served as latitude markers; the declination of Sirius matches the latitude of the archipelago of Fiji at 17°S and thus passes directly over the islands each sidereal day . Sirius served as the body of a "Great Bird" constellation called Manu , with Canopus as the southern wingtip and Procyon the northern wingtip, which divided

14344-553: The ancient Egyptians did not use coinage until the Late period , they did use a type of money-barter system, with standard sacks of grain and the deben , a weight of roughly 91 grams (3 oz) of copper or silver, forming a common denominator. Workers were paid in grain; a simple laborer might earn 5 + 1 ⁄ 2  sacks (200 kg or 400 lb) of grain per month, while a foreman might earn 7 + 1 ⁄ 2  sacks (250 kg or 550 lb). Prices were fixed across

14507-407: The ancient Egyptians include the quarrying , surveying , and construction techniques that supported the building of monumental pyramids , temples , and obelisks ; a system of mathematics , a practical and effective system of medicine , irrigation systems, and agricultural production techniques, the first known planked boats, Egyptian faience and glass technology, new forms of literature , and

14670-589: The ancient religion of Persia , Sirius appears as Tishtrya and is revered as the rain-maker divinity (Tishtar of New Persian poetry). Beside passages in the sacred texts of the Avesta , the Avestan language Tishtrya followed by the version Tir in Middle and New Persian is also depicted in the Persian epic Shahnameh of Ferdowsi . Because of the concept of the yazatas , powers which are "worthy of worship", Tishtrya

14833-405: The colour of Sirius preferentially when it was situated low in the sky (and therefore apparently red). In several Mediterranean cultures, the local visibility of Sirius at heliacal rising and setting (whether it appeared bright and clear or dimmed) was thought to have astrological significance and was thus subject to systematic observation and intense interest. Thus Sirius, more than any other star,

14996-603: The combination of the star's proper motion and the precession of the equinoxes . At the time of the introduction of the Gregorian calendar in the year 1582, its culmination occurred 17 minutes before midnight into the new year under the assumption of a constant motion. According to Richard Hinckley Allen its midnight culmination was celebrated at the Temple of Demeter at Eleusis . List of brightest stars Most stars on this list appear bright from Earth because they are nearby, not because they are intrinsically luminous . For

15159-410: The complaint, testimony, and verdict of the case for future reference. Punishment for minor crimes involved either imposition of fines, beatings, facial mutilation, or exile, depending on the severity of the offense. Serious crimes such as murder and tomb robbery were punished by execution, carried out by decapitation, drowning, or impaling the criminal on a stake. Punishment could also be extended to

15322-419: The conditions of the Nile River valley for agriculture . The predictable flooding and controlled irrigation of the fertile valley produced surplus crops, which supported a more dense population, and social development and culture. With resources to spare, the administration sponsored mineral exploitation of the valley and surrounding desert regions, the early development of an independent writing system ,

15485-497: The control of a prefect appointed by the emperor, quelled rebellions, strictly enforced the collection of heavy taxes, and prevented attacks by bandits, which had become a notorious problem during the period. Alexandria became an increasingly important center on the trade route with the orient, as exotic luxuries were in high demand in Rome. Although the Romans had a more hostile attitude than

15648-401: The country and recorded in lists to facilitate trading; for example a shirt cost five copper deben, while a cow cost 140   deben. Grain could be traded for other goods, according to the fixed price list. During the fifth century   BC coined money was introduced into Egypt from abroad. At first the coins were used as standardized pieces of precious metal rather than true money, but in

15811-403: The country's economy. Regional governors could not rely on the king for help in times of crisis, and the ensuing food shortages and political disputes escalated into famines and small-scale civil wars. Yet despite difficult problems, local leaders, owing no tribute to the king, used their new-found independence to establish a thriving culture in the provinces. Once in control of their own resources,

15974-421: The criminal's family. Beginning in the New Kingdom, oracles played a major role in the legal system, dispensing justice in both civil and criminal cases. The procedure was to ask the god a "yes" or "no" question concerning the right or wrong of an issue. The god, carried by a number of priests, rendered judgement by choosing one or the other, moving forward or backward, or pointing to one of the answers written on

16137-472: The diameter of the Moon) to the southwest. In 1868, Sirius became the first star to have its velocity measured, the beginning of the study of celestial radial velocities . Sir William Huggins examined the spectrum of the star and observed a red shift . He concluded that Sirius was receding from the Solar System at about 40 km/s. Compared to the modern value of −5.5 km/s, this was an overestimate and had

16300-411: The early modern period by Europeans and Egyptians has led to the scientific investigation of Egyptian civilization and a greater appreciation of its cultural legacy. The Nile has been the lifeline of its region for much of human history. The fertile floodplain of the Nile gave humans the opportunity to develop a settled agricultural economy and a more sophisticated, centralized society that became

16463-556: The economy and precipitated the slow decline into the Second Intermediate Period during the later Thirteenth and Fourteenth dynasties. During this decline, the Canaanite settlers began to assume greater control of the Delta region, eventually coming to power in Egypt as the Hyksos . Around 1785   BC, as the power of the Middle Kingdom kings weakened, a Western Asian people called the Hyksos , who had already settled in

16626-498: The entire star; rather the iron-peak and heavy metals are radiatively levitated towards the surface. Sirius B, also known as the Pup Star, is one of the most massive white dwarfs known. With a mass of 1.02  M ☉ , it is almost double the 0.5–0.6  M ☉ average. This mass is packed into a volume roughly equal to the Earth's. The current surface temperature

16789-565: The evening where it sets after the Sun and in the morning where it rises before the Sun. Along with Procyon and Betelgeuse , Sirius forms one of the three vertices of the Winter Triangle to observers in the Northern Hemisphere . Sirius can be observed in daylight with the naked eye under the right conditions. Ideally, the sky should be very clear, with the observer at a high altitude,

16952-540: The faint companion, which is now called Sirius B, or affectionately "the Pup". This happened during testing of an 18.5-inch (470 mm) aperture great refractor telescope for Dearborn Observatory , which was one of the largest refracting telescope lenses in existence at the time, and the largest telescope in the United States. Sirius B's sighting was confirmed on 8 March with smaller telescopes. The visible star

17115-424: The fertile delta region, as well as the lucrative and critical trade routes to the Levant . The increasing power and wealth of the kings during the early dynastic period was reflected in their elaborate mastaba tombs and mortuary cult structures at Abydos, which were used to celebrate the deified king after his death. The strong institution of kingship developed by the kings served to legitimize state control over

17278-470: The fertility of their land. The ancient Greeks observed that the appearance of Sirius as the morning star heralded the hot and dry summer and feared that the star caused plants to wilt, men to weaken, and women to become aroused. Owing to its brightness, Sirius would have been seen to twinkle more in the unsettled weather conditions of early summer. To Greek observers, this signified emanations that caused its malignant influence. Anyone suffering its effects

17441-524: The financial obligations of the husband to his wife and children should the marriage end. Compared with their counterparts in ancient Greece, Rome, and even more modern places around the world, ancient Egyptian women had a greater range of personal choices, legal rights, and opportunities for achievement. Women such as Hatshepsut and Cleopatra VII even became pharaohs, while others wielded power as Divine Wives of Amun . Despite these freedoms, ancient Egyptian women did not often take part in official roles in

17604-594: The first recorded peace treaty , around 1258   BC. Egypt's wealth, however, made it a tempting target for invasion, particularly by the Libyan Berbers to the west, and the Sea Peoples , a conjectured confederation of seafarers from the Aegean Sea . Initially, the military was able to repel these invasions, but Egypt eventually lost control of its remaining territories in southern Canaan , much of it falling to

17767-427: The floodwaters had receded, the growing season lasted from October to February. Farmers plowed and planted seeds in the fields, which were irrigated with ditches and canals. Egypt received little rainfall, so farmers relied on the Nile to water their crops. From March to May, farmers used sickles to harvest their crops, which were then threshed with a flail to separate the straw from the grain. Winnowing removed

17930-417: The following centuries international traders came to rely on coinage. Egyptian society was highly stratified, and social status was expressly displayed. Farmers made up the bulk of the population, but agricultural produce was owned directly by the state, temple, or noble family that owned the land. Farmers were also subject to a labor tax and were required to work on irrigation or construction projects in

18093-412: The government, who relied on a bureaucracy of officials to manage his affairs. In charge of the administration was his second in command, the vizier , who acted as the king's representative and coordinated land surveys, the treasury, building projects, the legal system, and the archives . At a regional level, the country was divided into as many as 42 administrative regions called nomes each governed by

18256-557: The indigenous peoples of North America also associated Sirius with canines; the Seri and Tohono Oʼodham of the southwest note the star as a dog that follows mountain sheep, while the Blackfoot called it "Dog-face". The Cherokee paired Sirius with Antares as a dog-star guardian of either end of the "Path of Souls". The Pawnee of Nebraska had several associations; the Wolf (Skidi) tribe knew it as

18419-411: The king in payment for their services. Kings also made land grants to their mortuary cults and local temples , to ensure that these institutions had the resources to worship the king after his death. Scholars believe that five centuries of these practices slowly eroded the economic vitality of Egypt, and that the economy could no longer afford to support a large centralized administration. As the power of

18582-575: The kingdom's capital to the city of Itjtawy , located in Faiyum . From Itjtawy, the kings of the Twelfth Dynasty undertook a far-sighted land reclamation and irrigation scheme to increase agricultural output in the region. Moreover, the military reconquered territory in Nubia that was rich in quarries and gold mines, while laborers built a defensive structure in the Eastern Delta, called the " Walls of

18745-517: The kings diminished, regional governors called nomarchs began to challenge the supremacy of the office of king. This, coupled with severe droughts between 2200 and 2150   BC, is believed to have caused the country to enter the 140-year period of famine and strife known as the First Intermediate Period. After Egypt's central government collapsed at the end of the Old Kingdom, the administration could no longer support or stabilize

18908-556: The land, labor, and resources that were essential to the survival and growth of ancient Egyptian civilization. Major advances in architecture, art, and technology were made during the Old Kingdom , fueled by the increased agricultural productivity and resulting population growth, made possible by a well-developed central administration. Some of ancient Egypt's crowning achievements, the Giza pyramids and Great Sphinx , were constructed during

19071-493: The long line of kings from Menes to his own time into 30 dynasties, a system still used today. He began his official history with the king named "Meni" (or Menes in Greek), who was believed to have united the two kingdoms of Upper and Lower Egypt . The transition to a unified state happened more gradually than ancient Egyptian writers represented, and there is no contemporary record of Menes. Some scholars now believe, however, that

19234-522: The mass of Jupiter at 1–2 AU distance, and down to around 4 times the mass of Jupiter at 10 AU distance. Similarly, Lucas and colleagues did not detect any companions around Sirius B. Sirius A, also known as the Dog Star, has a mass of 2.063  M ☉ . The radius of this star has been measured by an astronomical interferometer , giving an estimated angular diameter of 5.936±0.016  mas . The projected rotational velocity

19397-464: The mid-first century AD, Christianity took root in Egypt and it was originally seen as another cult that could be accepted. However, it was an uncompromising religion that sought to win converts from the pagan Egyptian and Greco-Roman religions and threatened popular religious traditions. This led to the persecution of converts to Christianity, culminating in the great purges of Diocletian starting in 303, but eventually Christianity won out. In 391,

19560-514: The mythical Menes may have been the king Narmer , who is depicted wearing royal regalia on the ceremonial Narmer Palette, in a symbolic act of unification. In the Early Dynastic Period, which began about 3000   BC, the first of the Dynastic kings solidified control over lower Egypt by establishing a capital at Memphis , from which he could control the labor force and agriculture of

19723-428: The next brightest star. Sirius is a binary star consisting of a main-sequence star of spectral type A0 or A1 , termed Sirius A, and a faint white dwarf companion of spectral type DA2, termed Sirius B. The distance between the two varies between 8.2 and 31.5  astronomical units as they orbit every 50 years. Sirius appears bright because of its intrinsic luminosity and its proximity to

19886-405: The nobility were the priests, physicians, and engineers with specialized training in their field. It is unclear whether slavery as understood today existed in ancient Egypt; there is difference of opinions among authors. The ancient Egyptians viewed men and women, including people from all social classes, as essentially equal under the law, and even the lowliest peasant was entitled to petition

20049-658: The north, while a rival clan based in Thebes , the Intef family , took control of Upper Egypt in the south. As the Intefs grew in power and expanded their control northward, a clash between the two rival dynasties became inevitable. Around 2055   BC the northern Theban forces under Nebhepetre Mentuhotep II finally defeated the Herakleopolitan rulers, reuniting the Two Lands. They inaugurated

20212-670: The northern part of Egypt, ruling from the city of Tanis . The south was effectively controlled by the High Priests of Amun at Thebes , who recognized Smendes in name only. During this time, Libyans had been settling in the western delta, and chieftains of these settlers began increasing their autonomy. Libyan princes took control of the delta under Shoshenq I in 945   BC, founding the so-called Libyan or Bubastite dynasty that would rule for some 200 years. Shoshenq also gained control of southern Egypt by placing his family members in important priestly positions. Libyan control began to erode as

20375-462: The organization of collective construction and agricultural projects, trade with surrounding regions, and a military intended to assert Egyptian dominance. Motivating and organizing these activities was a bureaucracy of elite scribes , religious leaders, and administrators under the control of a pharaoh , who ensured the cooperation and unity of the Egyptian people in the context of an elaborate system of religious beliefs . The many achievements of

20538-541: The political unification of Upper and Lower Egypt under pharaoh or king Menes (often identified with Narmer ). The history of ancient Egypt unfolded as a series of stable kingdoms interspersed by periods of relative instability known as "Intermediate Periods". The various kingdoms fall into one of three categories: the Old Kingdom of the Early Bronze Age , the Middle Kingdom of the Middle Bronze Age , or

20701-524: The previously obscure sun deity Aten as the supreme deity , suppressed the worship of most other deities, and moved the capital to the new city of Akhetaten (modern-day Amarna ). He was devoted to his new religion and artistic style . After his death, the cult of the Aten was quickly abandoned and the traditional religious order restored. The subsequent pharaohs, Tutankhamun , Ay , and Horemheb , worked to erase all mention of Akhenaten's heresy, now known as

20864-614: The provinces became economically richer—which was demonstrated by larger and better burials among all social classes. In bursts of creativity, provincial artisans adopted and adapted cultural motifs formerly restricted to the royalty of the Old Kingdom, and scribes developed literary styles that expressed the optimism and originality of the period. Free from their loyalties to the king, local rulers began competing with each other for territorial control and political power . By 2160   BC, rulers in Herakleopolis controlled Lower Egypt in

21027-440: The redness of the Sun at sunrise and sunset . Because the particles that cause reddening in the Earth's atmosphere are different (typically much smaller) than those that cause reddening in the interstellar medium, there is far less dimming of the starlight, and in the case of Sirius the change in colour can be seen without the aid of a telescope. There may be cultural reasons to explain why some ancient observers might have reported

21190-688: The role of the Egyptian temple priests and priestesses diminished. The temples themselves were sometimes converted to churches or abandoned to the desert. In the fourth century, as the Roman Empire divided, Egypt found itself in the Eastern Empire with its capital at Constantinople . In the waning years of the Empire, Egypt fell to the Sasanian Persian army in the Sasanian conquest of Egypt (618–628). It

21353-402: The size of a herd reflected the prestige and importance of the estate or temple that owned them. In addition to cattle, the ancient Egyptians kept sheep, goats, and pigs. Poultry , such as ducks, geese, and pigeons, were captured in nets and bred on farms, where they were force-fed with dough to fatten them. The Nile provided a plentiful source of fish . Bees were also domesticated from at least

21516-452: The star has been known as Lokabrenna ("burning done by Loki", or "Loki's torch"). In the astrology of the Middle Ages , Sirius was a Behenian fixed star , associated with beryl and juniper . Its astrological symbol [REDACTED] was listed by Heinrich Cornelius Agrippa . Many cultures have historically attached special significance to Sirius, particularly in relation to dogs . It

21679-414: The star passing overhead, and the Sun low on the horizon. These observing conditions are more easily met in the Southern Hemisphere, owing to the southerly declination of Sirius. The orbital motion of the Sirius binary system brings the two stars to a minimum angular separation of 3  arcseconds and a maximum of 11 arcseconds. At the closest approach, it is an observational challenge to distinguish

21842-684: The star system, but given its size it still appears at magnitude 8.3. The proper name "Sirius" comes from the Latin Sīrius , from the Ancient Greek Σείριος ( Seirios , "glowing" or "scorcher"). The Greek word itself may have been imported from elsewhere before the Archaic period , one authority suggesting a link with the Egyptian god Osiris . The name's earliest recorded use dates from the 7th century BC in Hesiod 's poetic work Works and Days . In 2016,

22005-426: The star to some degree, but reddening sufficient to cause it to appear similar in colour to intrinsically red bright stars such as Betelgeuse and Arcturus would also dim the star by several magnitudes, inconsistent with historical accounts: indeed, the dimming would be sufficient to render the colour of the star imperceptible to the human eye without the aid of a telescope. Extrinsic theories based on optical effects in

22168-498: The system, which is considered somewhat unusual for a binary star. The Chandra X-ray Observatory image shows Sirius B outshining its partner as an X-ray source. In 2015, Vigan and colleagues used the VLT Survey Telescope to search for evidence of substellar companions, and were able to rule out the presence of giant planets 11 times more massive than Jupiter at 0.5 AU distance from Sirius A, 6–7 times

22331-576: The two stars are believed to be too far apart for it to occur, even if Sirius A swells into a red giant . Novas , however, may be possible. Since 1894, irregularities have been tentatively observed in the orbits of Sirius A and B with an apparent periodicity of 6–6.4 years. A 1995 study concluded that such a companion likely exists, with a mass of roughly 0.05 solar mass—a small red dwarf or large brown dwarf , with an apparent magnitude of more than 15, and less than 3 arcseconds from Sirius A. In 2017, more accurate astrometric observations by

22494-489: The two states became inevitable. Between 671 and 667   BC the Assyrians began the Assyrian conquest of Egypt . The reigns of both Taharqa and his successor, Tanutamun , were filled with constant conflict with the Assyrians, against whom Egypt enjoyed several victories. Ultimately, the Assyrians pushed the Kushites back into Nubia, occupied Memphis, and sacked the temples of Thebes . The Assyrians left control of Egypt to

22657-408: The value of the parallax was 0.23  arcsecond , and error of the parallax was estimated not to exceed a quarter of a second, or as Henderson wrote in 1839, "On the whole we may conclude that the parallax of Sirius is not greater than half a second in space; and that it is probably much less." Astronomers adopted a value of 0.25 arcsecond for much of the 19th century. It is now known to have

22820-458: The visual brightness of stars is not perfectly defined for four reasons: All of these stars have multiple valid names or catalogue designations . The table lists their Bayer designation and the most common proper name . Most of the proper names have been approved by the Working Group on Star Names of the International Astronomical Union (IAU). Popular names which have not been approved by

22983-431: The visual spectrum, Sirius B was once the more massive of the two. The age of the system has been estimated at 230 million years. Early in its life, it is thought to have been two bluish-white stars orbiting each other in an elliptical orbit every 9.1 years. The system emits a higher than expected level of infrared radiation , as measured by IRAS space-based observatory. This might be an indication of dust in

23146-428: The white dwarf from its more luminous companion, requiring a telescope with at least 300 mm (12 in) aperture and excellent seeing conditions. After a periastron occurred in 1994, the pair moved apart, making them easier to separate with a telescope. Apoastron occurred in 2019, but from the Earth's vantage point, the greatest observational separation occurred in 2023, with an angular separation of 11.333″. At

23309-520: The wrong sign; the minus sign (−) means that it is approaching the Sun. In his 1698 book, Cosmotheoros , Christiaan Huygens estimated the distance to Sirius at 27,664 times the distance from the Earth to the Sun (about 0.437 light-year, translating to a parallax of roughly 7.5 arcseconds). There were several unsuccessful attempts to measure the parallax of Sirius: by Jacques Cassini (6 seconds); by some astronomers (including Nevil Maskelyne ) using Lacaille 's observations made at

23472-445: The year 66,270 AD. In that year, Sirius will come to within 1.6 degrees of the south celestial pole. This is due to axial precession and proper motion of Sirius itself which moves slowly in the SSW direction, so it will be visible from the southern hemisphere only. After that time, its distance will begin to increase, and it will become fainter, but it will continue to be the brightest star in

23635-410: Was a B-type star (most likely B5V for 5  M ☉ ) when it was still on the main sequence, potentially burning around 600–1200 times more luminous than the sun. While it passed through the red giant stage, Sirius B may have enriched the metallicity of its companion, explaining the very high metallicity of Sirius A. This star is primarily composed of a carbon–oxygen mixture that

23798-638: Was a member of the Ursa Major Moving Group , based on his observations of the system's movements across the sky. The Ursa Major Group is a set of 220 stars that share a common motion through space. It was once a member of an open cluster , but has since become gravitationally unbound from the cluster. Analyses in 2003 and 2005 found Sirius's membership in the group to be questionable: the Ursa Major Group has an estimated age of 500 ± 100 million years, whereas Sirius, with metallicity similar to

23961-412: Was also able to rule out any companions to Sirius B with more than 0.024 solar mass (25 Jupiter masses) orbiting in 0.5 year, and 0.0095 (10 Jupiter masses) orbiting in 1.8 years. Effectively, there are almost certainly no additional bodies in the Sirius system larger than a small brown dwarf or large exoplanet. In 1909, Ejnar Hertzsprung was the first to suggest that Sirius

24124-538: Was also the beginning of trade with Mesopotamia , which continued into the early dynastic period and beyond. Over a period of about 1,000 years, the Naqada culture developed from a few small farming communities into a powerful civilization whose leaders were in complete control of the people and resources of the Nile valley. Establishing a power center at Nekhen (in Greek, Hierakonpolis), and later at Abydos , Naqada III leaders expanded their control of Egypt northwards along

24287-423: Was based on a common-sense view of right and wrong that emphasized reaching agreements and resolving conflicts rather than strictly adhering to a complicated set of statutes. Local councils of elders, known as Kenbet in the New Kingdom, were responsible for ruling in court cases involving small claims and minor disputes. More serious cases involving murder, major land transactions, and tomb robbery were referred to

24450-587: Was called Canicula, "little dog". The excessive panting of dogs in hot weather was thought to place them at risk of desiccation and disease. In extreme cases, a foaming dog might have rabies, which could infect and kill humans they had bitten. Homer , in the Iliad , describes the approach of Achilles toward Troy in these words: Sirius rises late in the dark, liquid sky On summer nights, star of stars, Orion's Dog they call it, brightest Of all, but an evil portent, bringing heat And fevers to suffering humanity. In

24613-412: Was claimed to be Sirius. The authors proposed this as evidence that Sirius B had been a red giant at the time of observation. Other scholars replied that it was likely St. Gregory had been referring to Arcturus . It is notable that not all ancient observers saw Sirius as red. The 1st-century poet Marcus Manilius described it as "sea-blue", as did the 4th-century Avienius . Furthermore, Sirius

24776-489: Was consistently reported as a white star in ancient China: a detailed re-evaluation of Chinese texts from the 2nd century BC up to the 7th century AD concluded that all such reliable sources are consistent with Sirius being white. Nevertheless, historical accounts referring to Sirius as red are sufficiently extensive to lead researchers to seek possible physical explanations. Proposed theories fall into two categories: intrinsic and extrinsic. Intrinsic theories postulate

24939-421: Was crucial in ancient Egypt because taxes were assessed based on the amount of land a person owned. Farming in Egypt was dependent on the cycle of the Nile River. The Egyptians recognized three seasons: Akhet (flooding), Peret (planting), and Shemu (harvesting). The flooding season lasted from June to September, depositing on the river's banks a layer of mineral-rich silt ideal for growing crops. After

25102-462: Was derived entirely from nuclear reactions. The core became convective and used the CNO cycle for energy generation. It is calculated that Sirius A will have completely exhausted the store of hydrogen at its core within a billion (10) years of its formation, and will then evolve away from the main sequence. It will pass through a red giant stage and eventually become a white dwarf. Sirius A

25265-500: Was first measured by Robert Hanbury Brown and Richard Q. Twiss in 1959 at Jodrell Bank using their stellar intensity interferometer . In 2005, using the Hubble Space Telescope , astronomers determined that Sirius B has nearly the diameter of the Earth, 12,000 kilometres (7,500 mi), with a mass 102% of the Sun's. Around the year 150 AD, Claudius Ptolemy of Alexandria, an ethnic Greek Egyptian astronomer of

25428-532: Was followed by the Naqada culture : the Naqada I ( Amratian ), the Naqada II ( Gerzeh ), and Naqada III ( Semainean ). These brought a number of technological improvements. As early as the Naqada I Period, predynastic Egyptians imported obsidian from Ethiopia , used to shape blades and other objects from flakes . Mutual trade with the Levant was established during Naqada II ( c.  3600–3350 BC ); this period

25591-446: Was generated by helium fusion in the progenitor star. This is overlaid by an envelope of lighter elements, with the materials segregated by mass because of the high surface gravity. The outer atmosphere of Sirius B is now almost pure hydrogen—the element with the lowest mass—and no other elements are seen in its spectrum. Although Sirius A and B compose a binary system that is reminiscent of those that can undergo Type Ia supernova ,

25754-478: Was misty or faint then it foretold (or emanated) pestilence. Coins retrieved from the island from the 3rd century BC feature dogs or stars with emanating rays, highlighting Sirius's importance. The Romans celebrated the heliacal setting of Sirius around 25 April, sacrificing a dog, along with incense, wine, and a sheep, to the goddess Robigo so that the star's emanations would not cause wheat rust on wheat crops that year. Bright stars were important to

25917-556: Was never able to overthrow the Persians until the end of the century. Following its annexation by Persia, Egypt was joined with Cyprus and Phoenicia in the sixth satrapy of the Achaemenid Persian Empire . This first period of Persian rule over Egypt, also known as the Twenty-Seventh Dynasty , ended in 402   BC, when Egypt regained independence under a series of native dynasties. The last of these dynasties,

26080-446: Was observed and recorded while close to the horizon. Other contemporary cultures, such as Chinese, lacking this tradition, recorded Sirius only as white. With an apparent magnitude of −1.46, Sirius is the brightest star in the night sky , almost twice as bright as the second-brightest star, Canopus . From Earth , Sirius always appears dimmer than Jupiter and Venus , and at certain times also dimmer than Mercury and Mars . Sirius

26243-443: Was said to be "star-struck" ( ἀστροβόλητος , astrobólētos ). It was described as "burning" or "flaming" in literature. The season following the star's reappearance came to be known as the "dog days". The inhabitants of the island of Ceos in the Aegean Sea would offer sacrifices to Sirius and Zeus to bring cooling breezes and would await the reappearance of the star in summer. If it rose clear, it would portend good fortune; if it

26406-471: Was then recaptured by the Byzantine emperor Heraclius (629–639), and was finally captured by Muslim Rashidun army in 639–641, marking the end of both Byzantine rule and of the period typically considered Ancient Egypt. The pharaoh was the absolute monarch of the country and, at least in theory, wielded complete control of the land and its resources. The king was the supreme military commander and head of

26569-420: Was used to weave sheets of linen and to make clothing. Papyrus growing on the banks of the Nile River was used to make paper. Vegetables and fruits were grown in garden plots, close to habitations and on higher ground, and had to be watered by hand. Vegetables included leeks, garlic, melons, squashes, pulses, lettuce, and other crops, in addition to grapes that were made into wine. The Egyptians believed that

#442557