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Sirius is the brightest star in the
night sky The night sky is the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon. Natural light sources in a night sky include ...
. Its name is derived from the
Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...
word , or , meaning 'glowing' or 'scorching'. The star is designated α Canis Majoris, Latinized to Alpha Canis Majoris, and abbreviated Alpha CMa or α CMa. With a visual
apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...
of −1.46, Sirius is almost twice as bright as
Canopus Canopus is the brightest star in the southern constellation of Carina (constellation), Carina and the list of brightest stars, second-brightest star in the night sky. It is also Bayer designation, designated α Carinae, which is Lat ...
, the next brightest star. Sirius is a
binary star A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...
consisting of a
main-sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hert ...
star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...
of
spectral type In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grati ...
A0 or A1, termed Sirius A, and a faint
white dwarf A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes fro ...
companion of spectral type DA2, termed Sirius B. The distance between the two varies between 8.2 and 31.5
astronomical unit The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits t ...
s as they orbit every 50 years. Sirius appears bright because of its intrinsic
luminosity Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a st ...
and its proximity to the
Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
. At a distance of , the Sirius system is one of Earth's nearest neighbours. Sirius is gradually moving closer to the Solar System, so it is expected to increase in brightness slightly over the next 60,000 years, reaching a peak magnitude of −1.68. After that time, its distance will begin to increase, and it will become fainter, but it will continue to be the brightest star in the Earth's night sky for approximately the next 210,000 years, before
Vega Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only from the Sun, an ...
, another A-type star and more luminous than Sirius, becomes the brightest star. Sirius A is about twice as massive as the
Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
() and has an
absolute visual magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse logarithmic astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent magnitude that the object would have if it ...
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 Betelgeuse is a red supergiant of spectral type M1-2 and one of the largest stars visible to the naked eye. It is usually the tenth-brightest star in the night sky and, after Rigel, the second-brightest in the constellation of Orion ...
, or
Rigel Rigel is a blue supergiant star in the constellation of Orion. It has the Bayer designation β Orionis, which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori. Rigel is the brightest and most massive componentand ...
. The system is between 200 and 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 A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around or ...
before shedding its outer layers and collapsing into its current state as a white dwarf around years ago. Sirius is known colloquially as the "Dog Star", reflecting its prominence in its
constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...
,
Canis Major Canis Major is a constellation in the Southern Celestial Hemisphere, southern celestial hemisphere. In the second century, it was included in Ptolemy's 48 constellations, and is counted among the 88 modern constellations. Its name is Latin fo ...
(the Greater Dog). The
heliacal rising The heliacal rising ( ) or star rise of a star occurs annually, or the similar phenomenon of a planet, when it first becomes visible above the eastern horizon at dawn just before sunrise (thus becoming "the morning star") after a complete orbit of ...
of Sirius marked the
flooding of the Nile The flooding of the Nile has been an important natural cycle in Egypt since Ancient Egypt, ancient times. It is celebrated by Egyptians as an annual holiday for two weeks starting August 15, known as ''Wafaa El-Nil''. It is also celebrated in the ...
in Ancient Egypt and the "
dog days The dog days or are the hot, sultry days of summer. They were historically the period following the heliacal rising of the star system Sirius (known colloquially as the "Dog Star"), which Hellenistic astrology connected with heat, drought, sud ...
" of summer for the
ancient Greeks Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cultu ...
, while to the
Polynesians Polynesians form an ethnolinguistic group of closely related people who are native to Polynesia (islands in the Polynesian Triangle), an expansive region of Oceania in the Pacific Ocean. They trace their early prehistoric origins to Island Sou ...
, mostly in the Southern Hemisphere, the star marked winter and was an important reference for their navigation around the Pacific Ocean.


Observational history

The brightest star seen from Earth, Sirius is recorded in some of the earliest astronomical records. Its displacement from the
ecliptic The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic again ...
causes its heliacal rising to be remarkably regular compared to other stars, with a period of almost exactly 365.25 days holding it constant relative to the
solar year A tropical year or solar year (or tropical period) is the time that the Sun takes to return to the same position in the sky of a celestial body of the Solar System such as the Earth, completing a full cycle of seasons; for example, the time fro ...
. This rising occurs at
Cairo Cairo ( ; ar, القاهرة, al-Qāhirah, ) is the capital of Egypt and its largest city, home to 10 million people. It is also part of the largest urban agglomeration in Africa, the Arab world and the Middle East: The Greater Cairo metro ...
on 19July ( Julian), placing it just before the onset of the annual flooding of the
Nile The Nile, , Bohairic , lg, Kiira , Nobiin language, Nobiin: Áman Dawū is a major north-flowing river in northeastern Africa. It flows into the Mediterranean Sea. The Nile is the longest river in Africa and has historically been considered ...
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 Sopdet is the ancient Egyptian name of the star Sirius and its personification as an Egyptian goddess. Known to the Greeks as Sothis, she was conflated with Isis as a goddess and Anubis as a god. Names The exact pronunciation of ancien ...
( egy, Spdt, "Triangle"; grc-gre, , ''Sō̂this''), guarantor of the fertility of their land. The
ancient Greeks Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cultu ...
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 Twinkle may refer to: * Twinkling, the variation of brightness of distant objects People * Twinkle (singer) (1948–2015), born Lynn Annette Ripley, English singer-songwriter * Twinkle Khanna, Indian movie actress * Twinkle Bajpai, female conte ...
more in the unsettled weather conditions of early summer. To Greek observers, this signified emanations that caused its malignant influence. Anyone suffering its effects was said to be "star-struck" (, ''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 Kea ( el, Κέα), also known as Tzia ( el, Τζια) and in antiquity Keos ( el, Κέως, la, Ceos), is a Greek island in the Cyclades archipelago in the Aegean Sea. Kea is part of the Kea-Kythnos regional unit. Geography It is the island o ...
in the
Aegean Sea The Aegean Sea ; tr, Ege Denizi (Greek language, Greek: Αιγαίο Πέλαγος: "Egéo Pélagos", Turkish language, Turkish: "Ege Denizi" or "Adalar Denizi") is an elongated embayment of the Mediterranean Sea between Europe and Asia. It ...
would offer sacrifices to Sirius and
Zeus Zeus or , , ; grc, Δῐός, ''Diós'', label=Genitive case, genitive Aeolic Greek, Boeotian Aeolic and Doric Greek#Laconian, Laconian grc-dor, Δεύς, Deús ; grc, Δέος, ''Déos'', label=Genitive case, genitive el, Δίας, ''D ...
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 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 Sacrifice is the offering of material possessions or the lives of animals or humans to a deity as an act of propitiation or worship. Evidence of ritual animal sacrifice has been seen at least since ancient Hebrews and Greeks, and possibly ex ...
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 the ancient
Polynesians Polynesians form an ethnolinguistic group of closely related people who are native to Polynesia (islands in the Polynesian Triangle), an expansive region of Oceania in the Pacific Ocean. They trace their early prehistoric origins to Island Sou ...
for navigation of the Pacific Ocean. They also served as latitude markers; the declination of Sirius matches the latitude of the archipelago of
Fiji Fiji ( , ,; fj, Viti, ; Fiji Hindi: फ़िजी, ''Fijī''), officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consists ...
at 17°S and thus passes directly over the islands each
sidereal day Sidereal time (as a unit also sidereal day or sidereal rotation period) (sidereal ) is a timekeeping system that astronomers use to locate celestial objects. Using sidereal time, it is possible to easily point a telescope to the proper coord ...
. Sirius served as the body of a "Great Bird" constellation called ''Manu'', with Canopus as the southern wingtip and
Procyon Procyon () is the brightest star in the constellation of Canis Minor and usually the eighth-brightest star in the night sky, with an apparent visual magnitude of 0.34. It has the Bayer designation α Canis Minoris, which is Latinize ...
the northern wingtip, which divided 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 Māori or Maori can refer to: Relating to the Māori people * Māori people of New Zealand, or members of that group * Māori language, the language of the Māori people of New Zealand * Māori culture * Cook Islanders, the Māori people of the C ...
, whose name ''Takurua'' described both the star and the season. Its culmination at the
winter solstice The winter solstice, also called the hibernal solstice, occurs when either of Earth's poles reaches its maximum tilt away from the Sun. This happens twice yearly, once in each hemisphere ( Northern and Southern). For that hemisphere, the winte ...
was marked by celebration in
Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...
, where it was known as ''Ka'ulua'', "Queen of Heaven". Many other Polynesian names have been recorded, including ''Tau-ua'' in the
Marquesas Islands The Marquesas Islands (; french: Îles Marquises or ' or '; Marquesan: ' ( North Marquesan) and ' ( South Marquesan), both meaning "the land of men") are a group of volcanic islands in French Polynesia, an overseas collectivity of France in th ...
, ''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.


Kinematics

In 1717,
Edmond Halley Edmond (or Edmund) Halley (; – ) was an English astronomer, mathematician and physicist. He was the second Astronomer Royal in Britain, succeeding John Flamsteed in 1720. From an observatory he constructed on Saint Helena in 1676–77, H ...
discovered the
proper motion Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...
of the hitherto presumed "fixed" stars after comparing contemporary
astrometric Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way. Histor ...
measurements with those from the second century AD given in Ptolemy's ''
Almagest The ''Almagest'' is a 2nd-century Greek-language mathematical and astronomical treatise on the apparent motions of the stars and planetary paths, written by Claudius Ptolemy ( ). One of the most influential scientific texts in history, it canoni ...
''. The bright stars
Aldebaran Aldebaran (Arabic: “The Follower”, "الدبران") is the brightest star in the zodiac constellation of Taurus. It has the Bayer designation α Tauri, which is Latinized to Alpha Tauri and abbreviated Alpha Tau or α Tau. Aldebar ...
,
Arcturus , - bgcolor="#FFFAFA" , Note (category: variability): , , H and K emission vary. Arcturus is the brightest star in the northern constellation of Boötes. With an apparent visual magnitude of −0.05, it is the third-brightest of the ...
and Sirius were noted to have moved significantly; Sirius had progressed about 30 arcminutes (about 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 The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the rate of change of the distance or range between the two points. It is equivalent to the vector projection o ...
. Sir
William Huggins Sir William Huggins (7 February 1824 – 12 May 1910) was an English astronomer best known for his pioneering work in astronomical spectroscopy together with his wife, Margaret. Biography William Huggins was born at Cornhill, Middlesex, in ...
examined the
spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors i ...
of the star and observed a
red shift In physics, a redshift is an increase in the wavelength, and corresponding decrease in the frequency and photon energy, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and simultaneous increase in fr ...
. 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 the wrong sign; the minus sign (−) means that it is approaching the Sun.


Distance

In his 1698 book, ''Cosmotheoros'',
Christiaan Huygens Christiaan Huygens, Lord of Zeelhem, ( , , ; also spelled Huyghens; la, Hugenius; 14 April 1629 – 8 July 1695) was a Dutch mathematician, physicist, engineer, astronomer, and inventor, who is regarded as one of the greatest scientists of ...
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 Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects ...
of Sirius: by
Jacques Cassini Jacques Cassini (18 February 1677 – 16 April 1756) was a French astronomer, son of the famous Italian astronomer Giovanni Domenico Cassini. Cassini was born at the Paris Observatory. Admitted at the age of seventeen to membership of the French ...
(6 seconds); by some astronomers (including
Nevil Maskelyne Nevil Maskelyne (; 6 October 1732 – 9 February 1811) was the fifth British Astronomer Royal. He held the office from 1765 to 1811. He was the first person to scientifically measure the mass of the planet Earth. He created the ''British Nau ...
) using
Lacaille Abbé Nicolas-Louis de Lacaille (; 15 March 171321 March 1762), formerly sometimes spelled de la Caille, was a French astronomer and geodesist who named 14 out of the 88 constellations. From 1750 to 1754, he studied the sky at the Cape of Good ...
's observations made at the
Cape of Good Hope The Cape of Good Hope ( af, Kaap die Goeie Hoop ) ;''Kaap'' in isolation: pt, Cabo da Boa Esperança is a rocky headland on the Atlantic coast of the Cape Peninsula in South Africa. A common misconception is that the Cape of Good Hope is t ...
(4 seconds); by Piazzi (the same amount); using Lacaille's observations made at
Paris Paris () is the capital and most populous city of France, with an estimated population of 2,165,423 residents in 2019 in an area of more than 105 km² (41 sq mi), making it the 30th most densely populated city in the world in 2020. S ...
, 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 Sir Thomas Maclear (17 March 1794 – 14 July 1879) was an Irish-born South African astronomer who became Her Majesty's astronomer at the Cape of Good Hope. Life He was born in Newtownstewart, County Tyrone, Ireland, the eldest son of Rev Jam ...
's observations made in 1836–1837, to determine that the value of the parallax was 0.23
arcsecond A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...
, 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 a parallax of nearly . The Hipparcos parallax for Sirius is only accurate to about light years, giving a distance of . Sirius B is generally assumed to be at the same distance. Sirius B has a
Gaia Data Release 3 The ''Gaia'' catalogues are star catalogues created using the results obtained by ''Gaia'' space telescope. The catalogues are released in stages that will contain increasing amounts of information; the early releases also miss some stars, especia ...
parallax with a much smaller statistical margin of error, giving a distance of , but it is flagged as having a very large value for astrometric excess noise, which indicates that the parallax value may be unreliable.


Discovery of Sirius B

In a letter dated 10 August 1844, the German astronomer
Friedrich Wilhelm Bessel Friedrich Wilhelm Bessel (; 22 July 1784 – 17 March 1846) was a German astronomer, mathematician, physicist, and geodesist. He was the first astronomer who determined reliable values for the distance from the sun to another star by the method ...
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 the faint companion, which is now called Sirius B, or affectionately "the Pup". This happened during testing of an aperture
great refractor Great refractor refers to a large telescope with a lens, usually the largest refractor at an observatory with an equatorial mount. The preeminence and success of this style in observational astronomy defines an era in modern telescopy in the 19t ...
telescope for
Dearborn Observatory The Dearborn Observatory is an astronomical observatory located on the Evanston, Illinois, Evanston campus of Northwestern University. The observatory was originally constructed in 1888, through an agreement between the university and the Chicago ...
, 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 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 . 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 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 Walter Sydney Adams (December 20, 1876 – May 11, 1956) was an American astronomer. Life and work Adams was born in Antioch, Turkey, to Lucien Harper Adams and Nancy Dorrance Francis Adams, missionary parents, and was brought to the U.S. i ...
, using a reflector at
Mount Wilson Observatory The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles. The observat ...
, observed the
spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors i ...
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 was first measured by
Robert Hanbury Brown Robert Hanbury Brown, AC FRS (31 August 1916 – 16 January 2002) was a British astronomer and physicist born in Aruvankadu, India. He made notable contributions to the development of radar and later conducted pioneering work in the field of ...
and
Richard Q. Twiss Richard Quintin Twiss (24 August 1920 – 20 May 2005) was a British astronomer. He is known for his work on the Hanbury-Brown and Twiss effect with Robert Hanbury Brown. It led to the development of the Hanbury Brown-Twiss intensity interfer ...
in 1959 at
Jodrell Bank Jodrell Bank Observatory () in Cheshire, England, hosts a number of radio telescopes as part of the Jodrell Bank Centre for Astrophysics at the University of Manchester. The observatory was established in 1945 by Bernard Lovell, a radio astron ...
using their stellar
intensity interferometer An intensity interferometer is the name given to devices that use the Hanbury Brown and Twiss effect. In astronomy, the most common use of such an astronomical interferometer is to determine the apparent angular diameter of a radio source or star. ...
. In 2005, using the
Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...
, astronomers determined that Sirius B has nearly the diameter of the Earth, , with a mass 102% of the Sun's.


Colour controversy

Around the year 150 AD, the Greek astronomer of the Roman period,
Ptolemy Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importanc ...
of Alexandria mapped the stars in Books VII and VIII of his ''
Almagest The ''Almagest'' is a 2nd-century Greek-language mathematical and astronomical treatise on the apparent motions of the stars and planetary paths, written by Claudius Ptolemy ( ). One of the most influential scientific texts in history, it canoni ...
'', 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 Betelgeuse is a red supergiant of spectral type M1-2 and one of the largest stars visible to the naked eye. It is usually the tenth-brightest star in the night sky and, after Rigel, the second-brightest in the constellation of Orion ...
,
Antares Antares is the brightest star in the constellation of Scorpius. It has the Bayer designation α Scorpii, which is Latinised to Alpha Scorpii. Often referred to as "the heart of the scorpion", Antares is flanked by σ Scorpii and τ S ...
,
Aldebaran Aldebaran (Arabic: “The Follower”, "الدبران") is the brightest star in the zodiac constellation of Taurus. It has the Bayer designation α Tauri, which is Latinized to Alpha Tauri and abbreviated Alpha Tau or α Tau. Aldebar ...
,
Arcturus , - bgcolor="#FFFAFA" , Note (category: variability): , , H and K emission vary. Arcturus is the brightest star in the northern constellation of Boötes. With an apparent visual magnitude of −0.05, it is the third-brightest of the ...
and Pollux, all of which are of orange or red hue. The discrepancy was first noted by amateur astronomer Thomas Barker, squire of Lyndon Hall in
Rutland Rutland () is a ceremonial county and unitary authority in the East Midlands, England. The county is bounded to the west and north by Leicestershire, to the northeast by Lincolnshire and the southeast by Northamptonshire. Its greatest len ...
, who prepared a paper and spoke at a meeting of the
Royal Society The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...
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 Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor, experimental photographer who invented the blueprint and did botanical wor ...
noted this in 1839, possibly influenced by witnessing
Eta Carinae Eta Carinae (η Carinae, abbreviated to η Car), formerly known as Eta Argus, is a stellar system containing at least two stars with a combined luminosity greater than five million times that of the Sun, located around distant in t ...
two years earlier.
Thomas Jefferson Jackson See Thomas Jefferson Jackson (T. J. J.) See (February 19, 1866 – July 4, 1962) was an American astronomer whose promulgated theories in astronomy and physics were eventually disproven. His educational and professional career were dogged by plagiar ...
resurrected discussion on red Sirius with the publication of several papers in 1892, and a final summary in 1926. He cited not only Ptolemy but also the poet
Aratus Aratus (; grc-gre, Ἄρατος ὁ Σολεύς; c. 315 BC/310 BC240) was a Greek didactic poet. His major extant work is his hexameter poem ''Phenomena'' ( grc-gre, Φαινόμενα, ''Phainómena'', "Appearances"; la, Phaenomena), the fi ...
, the orator
Cicero Marcus Tullius Cicero ( ; ; 3 January 106 BC – 7 December 43 BC) was a Roman statesman, lawyer, scholar, philosopher, and academic skeptic, who tried to uphold optimate principles during the political crises that led to the estab ...
, and general
Germanicus Germanicus Julius Caesar (24 May 15 BC – 10 October AD 19) was an ancient Roman general, known for his campaigns in Germania. The son of Nero Claudius Drusus and Antonia the Younger, Germanicus was born into an influential branch of the Patric ...
as 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 Seneca may refer to: People and language * Seneca (name), a list of people with either the given name or surname * Seneca people, one of the six Iroquois tribes of North America ** Seneca language, the language of the Seneca people Places Extrat ...
had described Sirius as being of a deeper red than
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
. Not all ancient observers saw Sirius as red. The 1st-century poet
Marcus Manilius Marcus Manilius (fl. 1st century AD) was a Roman poet, astrologer, and author of a poem in five books called '' Astronomica''. The ''Astronomica'' The author of ''Astronomica'' is neither quoted nor mentioned by any ancient writer. Even his ...
described it as "sea-blue", as did the 4th-century
Avienius Postumius Rufius Festus Avienius (sometimes erroneously Avienus) was a Latin writer of the 4th century AD. He was a native of Volsinii in Etruria, from the distinguished family of the Rufii Festi. Avienius is not identical with the historian Fe ...
. It was the standard white star in ancient China, and multiple records from the 2nd century BC up to the 7th century AD all describe Sirius as white. 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 Gregory of Tours (30 November 538 – 17 November 594 AD) was a Gallo-Roman historian and Bishop of Tours, which made him a leading prelate of the area that had been previously referred to as Gaul by the Romans. He was born Georgius Florenti ...
. 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" was claimed to be Sirius. The authors proposed this was further evidence Sirius B had been a red giant at the time. Other scholars replied that it was likely St. Gregory had been referring to
Arcturus , - bgcolor="#FFFAFA" , Note (category: variability): , , H and K emission vary. Arcturus is the brightest star in the northern constellation of Boötes. With an apparent visual magnitude of −0.05, it is the third-brightest of the ...
. The possibility that
stellar evolution Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is cons ...
of either Sirius A or Sirius B could be responsible for this discrepancy has been rejected by astronomers on the grounds that the timescale of thousands of years is much too short and that there is no sign of the nebulosity in the system that would be expected had such a change taken place. An interaction with a third star, to date undiscovered, has also been proposed as a possibility for a red appearance. Alternative explanations are either that the description as red is a poetic metaphor for ill fortune, or that the dramatic scintillations of the star when rising left the viewer with the impression that it was red. To the naked eye, it often appears to be flashing with red, white, and blue hues when near the horizon.


Observation

With an
apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's li ...
of −1.46, Sirius is the brightest star in the
night sky The night sky is the nighttime appearance of celestial objects like stars, planets, and the Moon, which are visible in a clear sky between sunset and sunrise, when the Sun is below the horizon. Natural light sources in a night sky include ...
, almost twice as bright as the second-brightest star,
Canopus Canopus is the brightest star in the southern constellation of Carina (constellation), Carina and the list of brightest stars, second-brightest star in the night sky. It is also Bayer designation, designated α Carinae, which is Lat ...
. From
Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
, Sirius always appears dimmer than
Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...
and
Venus Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never fa ...
, as well as
Mercury Mercury commonly refers to: * Mercury (planet), the nearest planet to the Sun * Mercury (element), a metallic chemical element with the symbol Hg * Mercury (mythology), a Roman god Mercury or The Mercury may also refer to: Companies * Merc ...
and
Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
at certain times. Sirius 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 Saint Petersburg ( rus, links=no, Санкт-Петербург, a=Ru-Sankt Peterburg Leningrad Petrograd Piter.ogg, r=Sankt-Peterburg, p=ˈsankt pʲɪtʲɪrˈburk), formerly known as Petrograd (1914–1924) and later Leningrad (1924–1991), i ...
). Because of its
declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. Declination's angle is measured north or south of the ...
of roughly −17°, Sirius is a
circumpolar star A circumpolar star is a star that, as viewed from a given latitude on Earth, never sets below the horizon due to its apparent proximity to one of the celestial poles. Circumpolar stars are therefore visible from said location toward the nearest ...
from latitudes south of 73° S. From the Southern Hemisphere in early July, Sirius can be seen in both the evening where it sets after the
Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...
and in the morning where it rises before the Sun. Along with
Procyon Procyon () is the brightest star in the constellation of Canis Minor and usually the eighth-brightest star in the night sky, with an apparent visual magnitude of 0.34. It has the Bayer designation α Canis Minoris, which is Latinize ...
and
Betelgeuse Betelgeuse is a red supergiant of spectral type M1-2 and one of the largest stars visible to the naked eye. It is usually the tenth-brightest star in the night sky and, after Rigel, the second-brightest in the constellation of Orion ...
, Sirius forms one of the three vertices of the
Winter Triangle The Winter Triangle is an astronomical asterism formed from three of the brightest stars in the winter sky. It is an imaginary equilateral triangle drawn on the celestial sphere, with its defining vertices at Sirius, Betelgeuse, and Procyon, the ...
to observers in the
Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...
. Sirius can be observed in
daylight Daylight is the combination of all direct and indirect sunlight during the daytime. This includes direct sunlight, diffuse sky radiation, and (often) both of these reflected by Earth and terrestrial objects, like landforms and buildings. Sunligh ...
with the naked eye under the right conditions. Ideally, the sky should be very clear, with the observer at a high altitude, 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 
arcsecond A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The na ...
s and a maximum of 11 arcseconds. At the closest approach, it is an observational challenge to distinguish the white dwarf from its more luminous companion, requiring a telescope with at least aperture and excellent seeing conditions. After a
periastron An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any elli ...
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 will occur in 2023, with an angular separation of 11.333". At a distance of 2.6 parsecs (8.6 ly), the Sirius system contains two of the eight List of nearest stars, 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 Rigel is a blue supergiant star in the constellation of Orion. It has the Bayer designation β Orionis, which is Latinized to Beta Orionis and abbreviated Beta Ori or β Ori. Rigel is the brightest and most massive componentand ...
or Betelgeuse.(Note that Canopus may be 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 of Sirius in approximately 296,000 years.


Stellar system

Sirius is a
binary star A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...
system consisting of two white stars orbiting each other with 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, main-sequence star of
spectral type In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grati ...
early A, with an estimated surface temperature of 9,940 Kelvin, 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 the visual spectrum, Sirius B was once the more massive of the two. The age of the system has been estimated at around 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 infrared excess, higher than expected level of infrared radiation, as measured by IRAS space-based observatory. This might be an indication of dust in 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 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

Sirius A has a mass of . The radius of this star has been measured by an astronomical interferometer, giving an estimated angular diameter of 5.936±0.016 milliarcsecond, mas. The stellar rotation, projected rotational velocity 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 Vega is the brightest star in the northern constellation of Lyra. It has the Bayer designation α Lyrae, which is Latinised to Alpha Lyrae and abbreviated Alpha Lyr or α Lyr. This star is relatively close at only from the Sun, an ...
, 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 years, its internal energy generation was derived entirely from nuclear reactions. The core became convection zone, 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 (109) years of its formation, and will then evolve away from the main sequence. It will pass through a
red giant A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around or ...
stage and eventually become a white dwarf. Sirius A is classed as an 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 the Sun, the proportion of iron in the atmosphere of Sirius A relative to hydrogen is given by \textstyle\left[\frac\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 the entire star; rather the iron-peak and heavy metals are radiatively levitated towards the surface.


Sirius B

Sirius B is one of the most massive
white dwarf A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes fro ...
s known. With a mass of , it is almost double the average. This mass is packed into a volume roughly equal to the Earth's. The current surface temperature 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 more than two billion years. A white dwarf forms after a star has evolved from the main sequence and then passed through a
red giant A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around or ...
stage. This occurred when Sirius B was less than half its current age, around 120 million years ago. The original star had an estimated and was a B-type star (most likely B5V for ) 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 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.


Apparent third star

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. More recent (and accurate) astrometric observations by the Hubble Space Telescope ruled out the existence of such a Sirius C entirely. The 1995 study predicted an astrometric movement of roughly 90 Milliarcsecond, 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) orbiting in 0.5 years, and 0.014 (15 Jupiter masses) in 2 years. The study 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.


Star cluster membership

In 1909, Ejnar Hertzsprung was the first to suggest that Sirius 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 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 of the Sun. The other two are the Hyades (star cluster), Hyades and the Pleiades, and each of these clusters consists of hundreds of stars.


Distant star cluster

In 2017, a massive star cluster was discovered only 10 Minute and second of arc, arcminutes from Sirius, making the two appear to be Angular distance, visually close to one other when viewed from the point of view of the
Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
. It was discovered during a statistical analysis of Gaia (spacecraft), ''Gaia'' data. The cluster is over a thousand times further away from us than the star system, but given its size it still appears at magnitude 8.3.


Etymology

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 Greece, 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, 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 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, 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 was listed by Heinrich Cornelius Agrippa.


Cultural significance

Many cultures have historically attached special significance to Sirius, particularly in relation to dogs. It is often colloquially called the "Dog Star" as the brightest star of
Canis Major Canis Major is a constellation in the Southern Celestial Hemisphere, southern celestial hemisphere. In the second century, it was included in Ptolemy's 48 constellations, and is counted among the 88 modern constellations. Its name is Latin fo ...
, the "Great Dog" constellation. Canis Major was classically depicted as Orion (mythology), 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 , and the star Sirius 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: In Iranian mythology, especially in Persian mythology and in Zoroastrianism, 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 Persian, Middle and New Persian is also depicted in the Persian literature, Persian epic ''Shahnameh'' of Ferdowsi. Because of the concept of the yazatas, powers which are "worthy of worship", Tishtrya 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" ( Pinyin, Chinese romanization: Tiānláng; Romanization of Japanese, Japanese romanization: Tenrō; Korean and romanization: 천랑 /Tsŏnrang) in the Well (Chinese constellation), Mansion of Jǐng (井宿). Many nations among the indigenous peoples of North America also associated Sirius with canines; the Seri people, 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 Antares is the brightest star in the constellation of Scorpius. It has the Bayer designation α Scorpii, which is Latinised to Alpha Scorpii. Often referred to as "the heart of the scorpion", Antares is flanked by σ Scorpii and τ S ...
as a dog-star guardian of either end of the "Path of Souls". The Pawnee people, Pawnee of Nebraska had several associations; the Wolf (Skidi) tribe knew it as 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 is depicted at the Dendera Temple complex, 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 (transliteration: ''aš-ši'rā'' or ''ash-shira''; the leader). The verse is: "", "That He 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 (Blavatskian), theosophy, it is believed the ''Seven Stars of the Pleiades in folklore and literature, Pleiades'' transmit the spiritual energy of the Seven Rays#In Theosophy, Seven Rays from the ''Galactic Logos'' to the ''Seven Stars of the Ursa Major, 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 Ancient Wisdom, 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, Gregorian Calendar during the decades around the year 2000. Over the years, its midnight culmination moves slowly, owing to the combination of the star's
proper motion Proper motion is the astrometric measure of the observed changes in the apparent places of stars or other celestial objects in the sky, as seen from the center of mass of the Solar System, compared to the abstract background of the more dista ...
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 mightnight culmination was celebrated at the Telesterion, Temple of Demeter at Eleusis.


Dogon

The Dogon people are an ethnic group in Mali, West Africa, reported by some researchers to have traditional astronomical knowledge about Sirius that would normally be considered impossible without the use of telescopes. According to Marcel Griaule, they knew about the fifty-year orbital period of Sirius and its companion prior to western astronomers. Doubts have been raised about the validity of Griaule and Dieterlein's work. In 1991, anthropologist Walter van Beek concluded about the Dogon, "Though they do speak about ''sigu tolo'' [which is what Griaule claimed the Dogon called Sirius] they disagree completely with each other as to which star is meant; for some it is an invisible star that should rise to announce the ''sigu'' [festival], for another it is Venus that, through a different position, appears as ''sigu tolo''. All agree, however, that they learned about the star from Griaule." According to Noah Brosch cultural transfer of relatively modern astronomical information could have taken place in 1893, when a French expedition arrived in Central West Africa to observe the total eclipse on 16 April. In his pseudoarcheology book ''The Sirius Mystery'', Robert Temple claimed that the Dogon people have a tradition of contact with intelligent extraterrestrial beings from Sirius.


Serer religion

In the Serer religion, religion of the Serer people of Senegal, the Gambia and Mauritania, Sirius is called ''Yoonir'' from the Serer language (and some of the Cangin languages, Cangin language speakers, who are all ethnically Serers). The star Sirius is one of the most important and sacred stars in Serer religion#Cosmology, Serer religious cosmology and symbolism. The Serer high priests and priestesses (Saltigues, the hereditary "rain priests") chart ''Yoonir'' in order to forecast rainfall and enable Serer farmers to start planting seeds. In Serer religious cosmology, it is the symbol of the universe.


Modern significance

Sirius features on the coat of arms of Macquarie University, and is the name of its alumnae journal. Seven ships of the Royal Navy have been called since the 18th century, with HMS Sirius (1786), the first being the flagship of the First Fleet to Australia in 1788. The Royal Australian Navy subsequently named a vessel in honor of the flagship. American vessels include the as well as a monoplane model—the Lockheed Sirius, the first of which was flown by Charles Lindbergh. The name was also adopted by Mitsubishi Motors as the Mitsubishi Sirius engine in 1980. The name of the North American satellite radio company CD Radio was changed to Sirius Satellite Radio in November 1999, being named after "the brightest star in the night sky". Sirius is one of the 27 stars on the flag of Brazil, where it represents the state of Mato Grosso. Composer Karlheinz Stockhausen, who wrote a piece called ''Sirius'', is claimed to have said on several occasions that he came from a planet in the Sirius system. To Stockhausen, Sirius stood for "the place where music is the highest of vibrations" and where music had been developed in the most perfect way.Michael Kurtz, ''Stockhausen. Eine Biografie''. Kassel, Bärenreiter Verlag, 1988: p. 271. Sirius has been the subject of poetry. Dante and John Milton reference the star, and it is the "powerful western fallen star" of Walt Whitman's "When Lilacs Last in the Dooryard Bloom'd", while Tennyson's poem The Princess (Tennyson poem), ''The Princess'' describes the star's scintillation (astronomy), scintillation:


Conjunctions and occultations

As Sirius is situated far south of the ecliptic, none of the planets of our solar system can be seen closer than 30 degrees to Sirius. However some planetoids with high-inclined orbits can be seen at rare occasions near Sirius or can even occult it. On February 19th, 2019 the small, 16.7 mag bright asteroid 4388 Jürgenstock, Jürgenstock occulted Sirius for observers in the Caribic and in South America and on October 9th, 2022 8.7 mag bright 2 Pallas, Pallas passed 8.5 arcminutes north of Sirius.


See also

* List of stars in Canis Major


Notes


References


Citations


Bibliography

* * *


External links

* * * * {{DEFAULTSORT:Sirius A-type main-sequence stars Am stars Articles containing video clips Astronomical objects known since antiquity Bayer objects, Canis Majoris, Alpha Binary stars Canis Major Durchmusterung objects, BD-16 1591 Flamsteed objects, Canis Majoris, 09 Gliese and GJ objects, 0244 Henry Draper Catalogue objects, 048915 Hipparcos objects, 032349 Bright Star Catalogue objects, 2491 Stars named from the Ancient Greek language White dwarfs TIC objects