135-450: Coma Berenices is an ancient asterism in the northern sky , which has been defined as one of the 88 modern constellations . It is in the direction of the fourth galactic quadrant , between Leo and Boötes , and it is visible in both hemispheres. Its name means "Berenice's Hair" in Latin and refers to Queen Berenice II of Egypt , who sacrificed her long hair as a votive offering . It
270-500: A cyclic quadrilateral , today called Ptolemy's theorem because its earliest extant source is a proof in the Almagest (I.10). The stereographic projection was ambiguously attributed to Hipparchus by Synesius (c. 400 AD), and on that basis Hipparchus is often credited with inventing it or at least knowing of it. However, some scholars believe this conclusion to be unjustified by available evidence. The oldest extant description of
405-511: A tanned elk-skin star map dated to at least the 17th century. In the South American Kalina mythology, the constellation was known as ombatapo (face). The constellation was also recognized by several Polynesian peoples . The people of Tonga had four names for Coma Berenices: Fatana-lua , Fata-olunga , Fata-lalo and Kapakau-o-Tafahi . The Boorong people called the constellation Tourt-chinboiong-gherra , and saw it as
540-491: A Messier or NGC designation, but is in the Melotte catalogue of open clusters (designated Melotte 111) and is also catalogued as Collinder 256. It is a large, diffuse open cluster of about 50 stars ranging between magnitudes five and ten, including several of Coma Berenices' stars which are visible to the naked eye. The cluster is spread over a huge region (more than five degrees across) near Gamma Comae Berenices . It has such
675-488: A cartographer ensured the constellation's inclusion on Dutch sky globes beginning in 1589. Tycho Brahe , also credited with Coma's designation as a constellation, included it in his 1602 star catalogue . Brahe recorded fourteen stars in the constellation; Johannes Hevelius increased its number to twenty-one, and John Flamsteed to forty-three. Coma Berenices also appeared in Johann Bayer 's 1603 Uranometria , and
810-529: A central bulge. NGC 4565 has at least two satellite galaxies , and one of them is interacting with it. NGC 4651 , about the size of the Milky Way , has tidal stellar streams gravitationally stripped from a smaller, satellite galaxy. It is about 62 million light-years away. It is located on the outskirts of the cluster, and is also known as the Umbrella Galaxy. Unlike the other spiral galaxies in
945-672: A corruption of another value attributed to a Babylonian source: 365 + 1 / 4 + 1 / 144 days (= 365.25694... days = 365 days 6 hours 10 min). It is not clear whether Hipparchus got the value from Babylonian astronomers or calculated by himself. Before Hipparchus, astronomers knew that the lengths of the seasons are not equal. Hipparchus made observations of equinox and solstice, and according to Ptolemy ( Almagest III.4) determined that spring (from spring equinox to summer solstice) lasted 94 1 ⁄ 2 days, and summer (from summer solstice to autumn equinox) 92 + 1 ⁄ 2 days. This
1080-460: A difference of approximately one day in approximately 300 years. So he set the length of the tropical year to 365 + 1 ⁄ 4 − 1 ⁄ 300 days (= 365.24666... days = 365 days 5 hours 55 min, which differs from the modern estimate of the value (including earth spin acceleration), in his time of approximately 365.2425 days, an error of approximately 6 min per year, an hour per decade, and ten hours per century. Between
1215-418: A few other 17th-century celestial maps followed suit. Coma Berenices and the now-obsolete Antinous are considered the first post-Ptolemaic constellations depicted on a celestial globe. With Antinous, Coma Berenices exemplified a trend in astronomy in which globe- and map-makers continued to rely on the ancients for data. This trend ended at the turn of the 16th century with observations of the southern sky and
1350-470: A large apparent size because it is relatively close, only 280 light-years or 86 parsecs away. M53 (NGC 5024) is a globular cluster which was discovered independently by Johann Elert Bode in 1775 and Charles Messier in February 1777; William Herschel was the first to resolve it into stars. The magnitude-7.7 cluster is 56,000 light-years from Earth. Only 1° away is NGC 5053 , a globular cluster with
1485-526: A larger, probably- elliptical galaxy. Coma Berenices contains the northern portion of the Virgo Cluster (also known as the Coma–Virgo Cluster), about 60 million light-years away. The portion includes six Messier galaxies. M85 (NGC 4382), considered elliptical or lenticular , is one of the cluster's brighter members at magnitude nine. M85 is interacting with the spiral galaxy NGC 4394 and
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#17327732258911620-697: A magnitude of 4.4 and a spectral class of K1III C. In the southwestern part of the constellation, it is 169 ± 2 light-years from Earth, Estimated to be around 1.79 times as massive as the Sun, it has expanded to around 10 times its radius. It is the brightest star in the Coma Star Cluster . With Alpha Comae Berenices and Beta Comae Berenices, Gamma Comae Berenices forms a 45-degree isosceles triangle from which Berenice's imaginary tresses hang. The star systems of Coma Berenices include binary , double and triple stars. 21 Comae Berenices ( proper name Kissin)
1755-589: A magnitude-nine spiral galaxy seen face-on, is one of the cluster's brightest. Photographs reveal a brilliant core, two prominent spiral arms, an array of secondary arms and several dust lanes . M64 (NGC 4826) is known as the Black Eye Galaxy because of the prominent dark dust lane in front of the galaxy's bright nucleus. Also known as the Sleeping Beauty and Evil Eye galaxy, it is about 17.3 million light-years away. Recent studies indicate that
1890-462: A more detailed discussion. Pliny ( Naturalis Historia II.X) tells us that Hipparchus demonstrated that lunar eclipses can occur five months apart, and solar eclipses seven months (instead of the usual six months); and the Sun can be hidden twice in thirty days, but as seen by different nations. Ptolemy discussed this a century later at length in Almagest VI.6. The geometry, and the limits of
2025-534: A more general concept than the 88 formally defined constellations . Constellations are based on asterisms, but unlike asterisms, constellations outline and today completely divide the sky and all its celestial objects into regions around their central asterisms. For example, the asterism known as the Big Dipper or the Plough comprises the seven brightest stars in the constellation Ursa Major . Another asterism
2160-486: A period of 2.4 days, is the prototype for the FK Comae Berenices class of variable stars and the star in which the " flip-flop phenomenon " was discovered. FS Comae Berenices is a semi-regular variable , a red giant with a period of about two months whose magnitude varies between 6.1 and 5.3. R Comae Berenices is a Mira variable with a maximum magnitude of almost 7. There are 123 RR Lyrae variables in
2295-439: A popular poem by Aratus based on the work by Eudoxus . Hipparchus also made a list of his major works that apparently mentioned about fourteen books, but which is only known from references by later authors. His famous star catalog was incorporated into the one by Ptolemy and may be almost perfectly reconstructed by subtraction of two and two-thirds degrees from the longitudes of Ptolemy's stars . The first trigonometric table
2430-505: A simpler sexagesimal system dividing a circle into 60 parts. Hipparchus also adopted the Babylonian astronomical cubit unit ( Akkadian ammatu , Greek πῆχυς pēchys ) that was equivalent to 2° or 2.5° ('large cubit'). Hipparchus probably compiled a list of Babylonian astronomical observations; Gerald J. Toomer , a historian of astronomy, has suggested that Ptolemy's knowledge of eclipse records and other Babylonian observations in
2565-477: A small flock of birds drinking rainwater from a puddle in the crotch of a tree. The people of the Pukapuka atoll may have called it Te Yiku-o-te-kiole , although sometimes this name is associated with Ursa Major . Coma Berenices is bordered by Boötes to the east, Canes Venatici to the north, Leo to the west and Virgo to the south. Covering 386.5 square degrees and 0.937% of the night sky, it ranks 42nd of
2700-570: A sparser nucleus of stars. Its total luminosity is the equivalent of about 16,000 suns, one of the lowest luminosities of any globular cluster. It was discovered by William Herschel in 1784. NGC 4147 is a somewhat dimmer globular cluster, with a much-smaller apparent size and an apparent magnitude of 10.7. The Coma Supercluster , itself part of the Coma Filament , contains the Coma and Leo Cluster of galaxies. The Coma Cluster ( Abell 1656)
2835-482: A star, known as ḪÉ.GÁL- a - a (translated as "which is before it") or MÚL.ḪÉ.GÁL- a - a , is tentatively considered part of Coma Berenices. It was also argued that Coma Berenices appears in Egyptian Ramesside star clocks as sb3w ꜥš3w , meaning "many stars". In Arabic astronomy Coma Berenices was known as Al-Dafira الضفيرة ("braid"), Al-Hulba الهلبة and Al-Thu'aba الذؤابة (both meaning "tuft"),
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#17327732258912970-540: A table giving the daily motion of the Moon according to the date within a long period. However, the Greeks preferred to think in geometrical models of the sky. At the end of the third century BC, Apollonius of Perga had proposed two models for lunar and planetary motion: Apollonius demonstrated that these two models were in fact mathematically equivalent. However, all this was theory and had not been put to practice. Hipparchus
3105-525: A tight range of only approximately ± 1 ⁄ 2 hour, guaranteeing (after division by 4,267) an estimate of the synodic month correct to one part in order of magnitude 10 million. Hipparchus could confirm his computations by comparing eclipses from his own time (presumably 27 January 141 BC and 26 November 139 BC according to Toomer ) with eclipses from Babylonian records 345 years earlier ( Almagest IV.2 ). Later al-Biruni ( Qanun VII.2.II) and Copernicus ( de revolutionibus IV.4) noted that
3240-453: A triangle formed by the two places and the Moon, and from simple geometry was able to establish a distance of the Moon, expressed in Earth radii. Because the eclipse occurred in the morning, the Moon was not in the meridian , and it has been proposed that as a consequence the distance found by Hipparchus was a lower limit. In any case, according to Pappus, Hipparchus found that the least distance
3375-431: Is 230 to 300 million light-years away. It is one of the largest-known clusters, with at least 10,000 galaxies (mainly elliptical , with a few spiral galaxies ). Due to its distance from Earth, most of the galaxies are visible only through large telescopes. Its brightest members are NGC 4874 and NGC 4889 , both with a magnitude of 13; most others are magnitude 15 or dimmer. NGC 4889 is a giant elliptical galaxy with one of
3510-522: Is 29.95 ± 0.10 light-years from Earth. A solar analog , it is a yellow-hued F-type main-sequence star with a spectral class of F9.5V B. Beta Comae Berenices is around 36% brighter, and 15% more massive than the Sun , and with a radius 10% larger. The second-brightest star in Coma Berenices is the 4.3-magnitude, bluish Alpha Comae Berenices (42 Comae Berenices), with the proper name Diadem, in
3645-485: Is 71 (from this eclipse), and the greatest 83 Earth radii. In the second book, Hipparchus starts from the opposite extreme assumption: he assigns a (minimum) distance to the Sun of 490 Earth radii. This would correspond to a parallax of 7′, which is apparently the greatest parallax that Hipparchus thought would not be noticed (for comparison: the typical resolution of the human eye is about 2′; Tycho Brahe made naked eye observation with an accuracy down to 1′). In this case,
3780-435: Is a close binary with nearly equal components and an orbital period of 26 years. The system is 272 ± 3 light-years away. The Coma Cluster contains at least eight spectroscopic binaries , and the constellation has seven eclipsing binaries : CC , DD , EK , RW , RZ , SS and UX Comae Berenices . There are over thirty double stars in Coma Berenices, including 24 Comae Berenices with contrasting colors. Its primary
3915-496: Is a bright, gravitationally lensed pair of quasars . W Comae Berenices (or ON 231), a blazar in the constellation's northwest, was originally designated a variable star and later found to be a BL Lacertae object . As of 2009, it had the most intense gamma ray spectrum of the sixty known gamma-ray blazars. Some gamma-ray bursts occurred in Coma Berenices, particularly GRB 050509B on 9 May 2005 and GRB 080607 on 7 June 2008. GRB 050509B, which lasted only 0.03 second, became
4050-504: Is a face-on barred spiral galaxy at a distance of 40 million light-years. It is unique for its region of intense star formation, creating a ring around its nucleus which was discovered by the Hubble Space Telescope . The galaxy's prodigious star formation began five million years ago, in a region with a diameter of 1,000 light-years. The core's structure is also unique because the galaxy has spiral arms which feed gas into
4185-400: Is also close to an integer number of years (4,267 moons : 4,573 anomalistic periods : 4,630.53 nodal periods : 4,611.98 lunar orbits : 344.996 years : 344.982 solar orbits : 126,007.003 days : 126,351.985 rotations). What was so exceptional and useful about the cycle was that all 345-year-interval eclipse pairs occur slightly more than 126,007 days apart within
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4320-463: Is an orange-hued giant star with a magnitude of 5.0, 610 light-years from Earth, and its secondary is a blue-white-hued star with a magnitude of 6.6. Triple stars include 12 Comae Berenices , 17 Comae Berenices , KR Comae Berenices and Struve 1639 . Over 200 variable stars are known in Coma Berenices, although many are obscure. Alpha Comae Berenices is a possible Algol variable . FK Comae Berenices , which varies from magnitude 8.14 to 8.33 over
4455-401: Is consistent with 94 + 1 ⁄ 4 and 92 + 1 ⁄ 2 days, an improvement on the results ( 94 + 1 ⁄ 2 and 92 + 1 ⁄ 2 days) attributed to Hipparchus by Ptolemy. Ptolemy made no change three centuries later, and expressed lengths for the autumn and winter seasons which were already implicit (as shown, e.g., by A. Aaboe ). Hipparchus also undertook to find
4590-512: Is inconsistent with a premise of the Sun moving around the Earth in a circle at uniform speed. Hipparchus's solution was to place the Earth not at the center of the Sun's motion, but at some distance from the center. This model described the apparent motion of the Sun fairly well. It is known today that the planets , including the Earth, move in approximate ellipses around the Sun, but this was not discovered until Johannes Kepler published his first two laws of planetary motion in 1609. The value for
4725-465: Is not particularly bright, as none of its stars are brighter than fourth magnitude , although there are 66 stars brighter than or equal to apparent magnitude 6.5. The constellation's brightest star is Beta Comae Berenices (43 Comae Berenices in Flamsteed designation , occasionally known as Al-Dafira), at magnitude 4.2 and with a high proper motion . In Coma Berenices' northeastern region, it
4860-411: Is post-Hipparchus so the direction of transmission is not settled by the tablets. Hipparchus was recognized as the first mathematician known to have possessed a trigonometric table , which he needed when computing the eccentricity of the orbits of the Moon and Sun. He tabulated values for the chord function, which for a central angle in a circle gives the length of the straight line segment between
4995-666: Is sometimes called the "father of astronomy", a title conferred on him by Jean Baptiste Joseph Delambre in 1817. Hipparchus was born in Nicaea ( ‹See Tfd› Greek : Νίκαια ), in Bithynia . The exact dates of his life are not known, but Ptolemy attributes astronomical observations to him in the period from 147 to 127 BC, and some of these are stated as made in Rhodes ; earlier observations since 162 BC might also have been made by him. His birth date ( c. 190 BC)
5130-434: Is the triangle , within the constellation of Capricornus . Asterisms range from simple shapes of just a few stars to more complex collections of many stars covering large portions of the sky. The stars themselves may be bright naked-eye objects or fainter, even telescopic, but they are generally all of a similar brightness to each other. The larger brighter asterisms are useful for people who are familiarizing themselves with
5265-482: Is the faintest object in Messier's catalog at magnitude 10.2. M98 (NGC 4192), a bright, elongated spiral galaxy seen nearly edge-on, appears elliptical because of its unusual angle. The magnitude-10 galaxy has no redshift . M99 (NGC 4254) is a spiral galaxy seen face-on. Like M98 it is of magnitude-10 and has an unusually long arm on its west side. Four supernovae have been observed in the galaxy. M100 (NGC 4321),
5400-532: Is the first astronomer known to attempt to determine the relative proportions and actual sizes of these orbits. Hipparchus devised a geometrical method to find the parameters from three positions of the Moon at particular phases of its anomaly. In fact, he did this separately for the eccentric and the epicycle model. Ptolemy describes the details in the Almagest IV.11. Hipparchus used two sets of three lunar eclipse observations that he carefully selected to satisfy
5535-513: Is the only modern constellation named for an historic figure. It was introduced to Western astronomy during the third century BC by Conon of Samos , the court astronomer of Egyptian ruler Ptolemy III Euergetes , to honour Ptolemy's consort, Berenice II . Berenice vowed to sacrifice her long hair as a votive offering if Ptolemy returned safely from battle during the Third Syrian War . Modern scholars are uncertain if Berenice made
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5670-485: Is visible simultaneously on half of the Earth, and the difference in longitude between places can be computed from the difference in local time when the eclipse is observed. His approach would give accurate results if it were correctly carried out but the limitations of timekeeping accuracy in his era made this method impractical. Late in his career (possibly about 135 BC) Hipparchus compiled his star catalog. Scholars have been searching for it for centuries. In 2022, it
5805-546: The 88 constellations by area . The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Com". The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of 12 segments ( illustrated in infobox ). In the equatorial coordinate system , the right ascension coordinates of these borders lie between 11 58 25.09 and 13 36 06.94 , and
5940-474: The Almagest came from a list made by Hipparchus. Hipparchus's use of Babylonian sources has always been known in a general way, because of Ptolemy's statements, but the only text by Hipparchus that survives does not provide sufficient information to decide whether Hipparchus's knowledge (such as his usage of the units cubit and finger, degrees and minutes, or the concept of hour stars) was based on Babylonian practice. However, Franz Xaver Kugler demonstrated that
6075-544: The Almagest . Some claim the table of Hipparchus may have survived in astronomical treatises in India, such as the Surya Siddhanta . Trigonometry was a significant innovation, because it allowed Greek astronomers to solve any triangle, and made it possible to make quantitative astronomical models and predictions using their preferred geometric techniques. Hipparchus must have used a better approximation for π than
6210-611: The Coma Star Cluster . The constellation's brightest star is Beta Comae Berenices, a 4.2- magnitude main sequence star similar to the Sun. Coma Berenices contains the North Galactic Pole and one of the richest-known galaxy clusters , the Coma Cluster , part of the Coma Supercluster . Galaxy Malin 1 , in the constellation, is the first-known giant low-surface-brightness galaxy . Supernova SN 1940B
6345-605: The Galactic Center . Some asterisms refer to portions of traditional constellation figures. These include: Other asterisms are also composed of stars from one constellation, but do not refer to the traditional figures. Other asterisms that are formed from stars in more than one constellation. Asterisms range from the large and obvious to the small, and even telescopic. Hipparchus Hipparchus ( / h ɪ ˈ p ɑːr k ə s / ; Greek : Ἵππαρχος , Hípparkhos ; c. 190 – c. 120 BC)
6480-622: The International Astronomical Union (IAU) precisely divided the sky into 88 official constellations following geometric boundaries encompassing all of the stars within them. Any additional new selected groupings of stars or former constellations are often considered as asterisms. However, technical distinctions between the terms 'constellation' and 'asterism' often remain somewhat ambiguous. Some asterisms consist completely of bright first-magnitude stars , which mark out simple geometric shapes. Other asterisms consist partially of multiple first-magnitude stars. All other first-magnitude stars are
6615-717: The Vedanga Jyotisha and the Babylonians . Different cultures identified different constellations, although a few of the more obvious patterns tend to appear in the constellations of multiple cultures, such as those of Orion and Scorpius . As anyone could arrange and name a grouping of stars there was no distinct difference between a constellation and an asterism . For example, Pliny the Elder mentions 72 asterisms in his book Naturalis Historia . A general list containing 48 constellations likely began to develop with
6750-461: The declination coordinates are between +13.30° and +33.31°. Coma Berenices is wholly visible to observers north of latitude 56°S . and the constellation's midnight culmination occurs on 2 April. Although it is not large, Coma Berenices contains one galactic supercluster , two galactic clusters , one star cluster and eight Messier objects (including several globular clusters ). These objects can be seen with minimal obscuration by dust because
6885-572: The eccentricity attributed to Hipparchus by Ptolemy is that the offset is 1 ⁄ 24 of the radius of the orbit (which is a little too large), and the direction of the apogee would be at longitude 65.5° from the vernal equinox . Hipparchus may also have used other sets of observations, which would lead to different values. One of his two eclipse trios' solar longitudes are consistent with his having initially adopted inaccurate lengths for spring and summer of 95 + 3 ⁄ 4 and 91 + 1 ⁄ 4 days. His other triplet of solar positions
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#17327732258917020-429: The interstellar gas in the galaxy's outer regions rotates in the opposite direction from that in the inner regions, leading astronomers to believe that at least one satellite galaxy collided with it less than a billion years ago. All other evidence of the smaller galaxy has been assimilated. At the interface between the clockwise- and counterclockwise-rotating regions are many new nebulae and young stars. NGC 4314
7155-585: The neutron star RBS 1223 and the pulsar PSR B1237+25 . RBS 1223 is a member of the Magnificent Seven , a group of young neutron stars. In 1975, the first extra-solar source of extreme ultraviolet , the white dwarf HZ 43 , was discovered in Coma Berenices. In 1995, there was a very rare outburst of the WZ Sagittae-type dwarf nova AL Comae Berenices . A June 2003 outburst from GO Comae Berenices , an SU Ursae Majoris-type dwarf nova,
7290-527: The 16th century. In 1515, a set of gores by Johannes Schöner labelled the asterism Trica , "hair". In 1536 it appeared on a celestial globe by Caspar Vopel , who is credited with the asterism's designation as a constellation. That year, it also appeared on a celestial map by Petrus Apianus as "Crines Berenices". In 1551, Coma Berenices appeared on a celestial globe by Gerardus Mercator with five Latin and Greek names: Cincinnus, caesaries , πλόκαμος , Berenicis crinis and Trica. Mercator's reputation as
7425-482: The 4th century BC and Timocharis and Aristillus in the 3rd century BC already divided the ecliptic in 360 parts (our degrees , Greek: moira) of 60 arcminutes and Hipparchus continued this tradition. It was only in Hipparchus's time (2nd century BC) when this division was introduced (probably by Hipparchus's contemporary Hypsikles) for all circles in mathematics. Eratosthenes (3rd century BC), in contrast, used
7560-569: The Countess Natalya Sollogub. The Swedish poet Gunnar Ekelöf wrote the lines "Your friend the comet combed his hair with the Leonids / Berenice let her hair hang down from the sky" in a 1933 poem. American writer and folksinger Richard Fariña mentions Coma Berenices in his 1966 novel Been Down So Long It Looks Like Up To Me , sardonically writing about content typical to upper-level astronomy coursework at Cornell : "It's
7695-533: The Geography of Eratosthenes"). It is known to us from Strabo of Amaseia, who in his turn criticised Hipparchus in his own Geographia . Hipparchus apparently made many detailed corrections to the locations and distances mentioned by Eratosthenes. It seems he did not introduce many improvements in methods, but he did propose a means to determine the geographical longitudes of different cities at lunar eclipses (Strabo Geographia 1 January 2012). A lunar eclipse
7830-601: The Greek. Prediction of a solar eclipse, i.e., exactly when and where it will be visible, requires a solid lunar theory and proper treatment of the lunar parallax. Hipparchus must have been the first to be able to do this. A rigorous treatment requires spherical trigonometry , thus those who remain certain that Hipparchus lacked it must speculate that he may have made do with planar approximations. He may have discussed these things in Perí tēs katá plátos mēniaías tēs selēnēs kinēseōs ("On
7965-584: The Hellespont and are thought by many to be more likely possibilities for the eclipse Hipparchus used for his computations.) Ptolemy later measured the lunar parallax directly ( Almagest V.13), and used the second method of Hipparchus with lunar eclipses to compute the distance of the Sun ( Almagest V.15). He criticizes Hipparchus for making contradictory assumptions, and obtaining conflicting results ( Almagest V.11): but apparently he failed to understand Hipparchus's strategy to establish limits consistent with
8100-409: The Moon eclipsed while apparently it was not in exact opposition to the Sun. Parallax lowers the altitude of the luminaries; refraction raises them, and from a high point of view the horizon is lowered. Hipparchus and his predecessors used various instruments for astronomical calculations and observations, such as the gnomon , the astrolabe , and the armillary sphere . Hipparchus is credited with
8235-458: The Moon's equation of the center in the Hipparchan model.) Before Hipparchus, Meton , Euctemon , and their pupils at Athens had made a solstice observation (i.e., timed the moment of the summer solstice ) on 27 June 432 BC ( proleptic Julian calendar ). Aristarchus of Samos is said to have done so in 280 BC, and Hipparchus also had an observation by Archimedes . He observed
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#17327732258918370-534: The Roman poet Catullus , and in Hyginus ' De Astronomica , she dedicated her tresses to Aphrodite and placed them in the temple of Arsinoe II (identified after Berenice's death with Aphrodite) at Zephyrium . According to De astronomica , by the next morning the tresses had disappeared. Conon proposed that Aphrodite had placed the tresses in the sky as an acknowledgement of Berenice's sacrifice. Callimachus called
8505-576: The Sun is on the equator (i.e., in one of the equinoctial points on the ecliptic ), but the shadow falls above or below the opposite side of the ring when the Sun is south or north of the equator. Ptolemy quotes (in Almagest III.1 (H195)) a description by Hipparchus of an equatorial ring in Alexandria; a little further he describes two such instruments present in Alexandria in his own time. Hipparchus applied his knowledge of spherical angles to
8640-496: The advanced courses give you trouble. Relativity principles, spiral nebula in Coma Berenices, that kind of hassle". The Bolivian poet, Pedro Shimose , makes Coma Berenices the home address of his "Señorita NGC 4565" in his poem "Carta a una estrella que vive en otra constelación" ("Letter to a star who lives in another constellation"), included in his 1967 collection, "Sardonia". " The Irish poet W. B. Yeats , in his poem "Her Dream", refers to "Berenice's burning hair" being "nailed upon
8775-448: The apparent diameter of the Sun and Moon. Pappus of Alexandria described it (in his commentary on the Almagest of that chapter), as did Proclus ( Hypotyposis IV). It was a four-foot rod with a scale, a sighting hole at one end, and a wedge that could be moved along the rod to exactly obscure the disk of Sun or Moon. Hipparchus also observed solar equinoxes , which may be done with an equatorial ring : its shadow falls on itself when
8910-407: The apparent diameters of the Sun and Moon with his diopter . Like others before and after him, he found that the Moon's size varies as it moves on its (eccentric) orbit, but he found no perceptible variation in the apparent diameter of the Sun. He found that at the mean distance of the Moon, the Sun and Moon had the same apparent diameter; at that distance, the Moon's diameter fits 650 times into
9045-550: The asterism plokamos Berenikēs or bostrukhon Berenikēs in Greek, translated into Latin as "Coma Berenices" by Catullus. Hipparchus and Geminus also recognized it as a distinct constellation. Eratosthenes called it "Berenice's Hair" and " Ariadne 's Hair", considering it part of the constellation Leo . Similarly, Ptolemy did not include it among his 48 constellations in the Almagest ; considering it part of Leo and calling it Plokamos . Coma Berenices became popular during
9180-436: The astronomer Hipparchus (c. 190 – c. 120 BCE). As constellations were considered to be composed only of the stars that constituted the figure, it was always possible to use any leftover stars to create and squeeze in a new grouping among the established constellations. Exploration by Europeans to other parts of the globe exposed them to stars previously unknown to them. Two astronomers particularly known for greatly expanding
9315-550: The bar. NGC 4414 is an unbarred spiral flocculent galaxy about 62 million light-years away. It is one of the closest flocculent spiral galaxies. NGC 4565 is an edge-on spiral galaxy which appears superimposed on the Virgo Cluster. NGC 4565 has been nicknamed the Needle Galaxy because when seen in full, it appears as a narrow streak of light. Like many edge-on spiral galaxies, it has a prominent dust lane and
9450-413: The center of the Earth, but the observer is at the surface—the Moon, Earth and observer form a triangle with a sharp angle that changes all the time. From the size of this parallax, the distance of the Moon as measured in Earth radii can be determined. For the Sun however, there was no observable parallax (we now know that it is about 8.8", several times smaller than the resolution of the unaided eye). In
9585-467: The change in the length of the day (see ΔT ) we estimate that the error in the assumed length of the synodic month was less than 0.2 second in the fourth century BC and less than 0.1 second in Hipparchus's time. It had been known for a long time that the motion of the Moon is not uniform: its speed varies. This is called its anomaly and it repeats with its own period; the anomalistic month . The Chaldeans took account of this arithmetically, and used
9720-466: The chords for angles with increments of 7.5°. In modern terms, the chord subtended by a central angle in a circle of given radius R equals R times twice the sine of half of the angle, i.e.: The now-lost work in which Hipparchus is said to have developed his chord table, is called Tōn en kuklōi eutheiōn ( Of Lines Inside a Circle ) in Theon of Alexandria 's fourth-century commentary on section I.10 of
9855-403: The circle, i.e., the mean apparent diameters are 360 ⁄ 650 = 0°33′14″. Like others before and after him, he also noticed that the Moon has a noticeable parallax , i.e., that it appears displaced from its calculated position (compared to the Sun or stars ), and the difference is greater when closer to the horizon. He knew that this is because in the then-current models the Moon circles
9990-412: The cluster, NGC 4651 is rich in neutral hydrogen, which also extends beyond the optical disk. Its star formation is typical for a galaxy of its type. Spiral galaxy Malin 1 discovered in 1986 is the first-known giant low-surface-brightness galaxy . With UGC 1382 , it is also one of the largest low-surface-brightness galaxies. In 2006 a dwarf galaxy , also named Coma Berenices , was discovered in
10125-577: The constellation from data obtained by the Sloan Digital Sky Survey . The galaxy is a faint satellite of the Milky Way. It is one of the faintest satellites of the Milky Way - its integrated luminosity is about 3700 times that of the Sun (absolute visible magnitude of about −4.1), which is lower than many globular clusters . A high mass to light ratio may mean that the satellite has large amounts of dark matter . HS 1216+5032
10260-503: The constellation is not in the direction of the galactic plane . Because of that, there are few open clusters (except for the Coma Berenices Cluster, which dominates the northern part of the constellation), diffuse nebulae or planetary nebulae . Coma Berenices contains the North Galactic Pole at right ascension 12 51 25 and declination +27° 07′ 48″ (epoch J2000.0 ). Coma Berenices
10395-495: The constellation, with many in the M53 cluster. One of these stars, TU Comae Berenices , may have a binary system . The M100 galaxy contains about twenty Cepheid variables , which were observed by the Hubble Space Telescope . Coma Berenices also contains Alpha Canum Venaticorum variables , such as 13 Comae Berenices and AI Comae Berenices . In 2019 scientists at Aryabhatta Research Institute of Observational Sciences announced
10530-657: The discovery of 28 new variable stars in Coma Berenices' globular cluster NGC 4147 . A number of supernovae have been discovered in Coma Berenices. Four ( SN 1940B , SN 1969H , SN 1987E and SN 1999gs ) were in the NGC 4725 galaxy, and another four were discovered in the M99 galaxy (NGC 4254): SN 1967H , SN 1972Q , SN 1986I and SN 2014L . Five were discovered in the M100 galaxy (NGC 4321): SN 1901B , SN 1914A , SN 1959E , SN 1979C and SN 2006X . SN 1940B, discovered on 5 May 1940,
10665-476: The distances and sizes of the Sun and the Moon, in the now-lost work On Sizes and Distances ( ‹See Tfd› Greek : Περὶ μεγεθῶν καὶ ἀποστημάτων Peri megethon kai apostematon ). His work is mentioned in Ptolemy's Almagest V.11, and in a commentary thereon by Pappus ; Theon of Smyrna (2nd century) also mentions the work, under the title On Sizes and Distances of the Sun and Moon . Hipparchus measured
10800-420: The elliptical galaxy MCG-3-32-38 . However, it is relatively isolated from the rest of the cluster. M88 (NGC 4501) is a multi-arm spiral galaxy seen at about 30° from edge-on. It has a highly-regular shape with well-developed, symmetrical arms. Among the first galaxies recognized as spiral, it has a supermassive black hole in its center. M91 (NGC 4548), a barred spiral galaxy with a bright, diffuse nucleus,
10935-510: The ending of The Rape of the Lock , in which the titular hair is placed among the stars. (The poem would go on to provide the names of some of the moons of Uranus .) In 1886, Spanish artist Luis Ricardo Falero created a mezzotint print personifying Coma Berenices alongside Virgo and Leo. In 1892, the Russian poet Afanasy Fet made the constellation the subject of his short poem, composed for
11070-573: The first book, Hipparchus assumes that the parallax of the Sun is 0, as if it is at infinite distance. He then analyzed a solar eclipse, which Toomer presumes to be the eclipse of 14 March 190 BC. It was total in the region of the Hellespont (and in his birthplace, Nicaea); at the time Toomer proposes the Romans were preparing for war with Antiochus III in the area, and the eclipse is mentioned by Livy in his Ab Urbe Condita Libri VIII.2. It
11205-481: The first century; Ptolemy's second-century Almagest ; and additional references to him in the fourth century by Pappus and Theon of Alexandria in their commentaries on the Almagest . Hipparchus's only preserved work is Commentary on the Phaenomena of Eudoxus and Aratus ( ‹See Tfd› Greek : Τῶν Ἀράτου καὶ Εὐδόξου φαινομένων ἐξήγησις ). This is a highly critical commentary in the form of two books on
11340-419: The first method is very sensitive to the accuracy of the observations and parameters. (In fact, modern calculations show that the size of the 189 BC solar eclipse at Alexandria must have been closer to 9 ⁄ 10 ths and not the reported 4 ⁄ 5 ths, a fraction more closely matched by the degree of totality at Alexandria of eclipses occurring in 310 and 129 BC which were also nearly total in
11475-411: The first short burst with a detected afterglow . The Coma Berenicids meteor shower peaks around 18 January. Despite the shower's low intensity (averaging one or two meteors per hour) its meteors are some of the fastest, with speeds up to 65 kilometres per second (40 mi/s). Since Callimachus' poem, Coma Berenices has been occasionally featured in culture. Alexander Pope alludes to the legend in
11610-429: The first surviving text discussing it is by Menelaus of Alexandria in the first century, who now, on that basis, commonly is credited with its discovery. (Previous to the finding of the proofs of Menelaus a century ago, Ptolemy was credited with the invention of spherical trigonometry.) Ptolemy later used spherical trigonometry to compute things such as the rising and setting points of the ecliptic , or to take account of
11745-400: The first to develop a reliable method to predict solar eclipses . His other reputed achievements include the discovery and measurement of Earth's precession, the compilation of the first known comprehensive star catalog from the western world, and possibly the invention of the astrolabe , as well as of the armillary sphere that he may have used in creating the star catalogue. Hipparchus
11880-440: The geometry of book 2 it follows that the Sun is at 2,550 Earth radii, and the mean distance of the Moon is 60 + 1 ⁄ 2 radii. Similarly, Cleomedes quotes Hipparchus for the sizes of the Sun and Earth as 1050:1; this leads to a mean lunar distance of 61 radii. Apparently Hipparchus later refined his computations, and derived accurate single values that he could use for predictions of solar eclipses. See Toomer (1974) for
12015-627: The greatest overall astronomer of antiquity . He was the first whose quantitative and accurate models for the motion of the Sun and Moon survive. For this he certainly made use of the observations and perhaps the mathematical techniques accumulated over centuries by the Babylonians and by Meton of Athens (fifth century BC), Timocharis , Aristyllus , Aristarchus of Samos , and Eratosthenes , among others. He developed trigonometry and constructed trigonometric tables , and he solved several problems of spherical trigonometry . With his solar and lunar theories and his trigonometry, he may have been
12150-447: The invention or improvement of several astronomical instruments, which were used for a long time for naked-eye observations. According to Synesius of Ptolemais (4th century) he made the first astrolabion : this may have been an armillary sphere (which Ptolemy however says he constructed, in Almagest V.1); or the predecessor of the planar instrument called astrolabe (also mentioned by Theon of Alexandria ). With an astrolabe Hipparchus
12285-449: The large total lunar eclipse of 26 November 139 BC, when over a clean sea horizon as seen from Rhodes, the Moon was eclipsed in the northwest just after the Sun rose in the southeast. This would be the second eclipse of the 345-year interval that Hipparchus used to verify the traditional Babylonian periods: this puts a late date to the development of Hipparchus's lunar theory. We do not know what "exact reason" Hipparchus found for seeing
12420-487: The largest-known black holes (21 billion solar masses ), and NGC 4921 is the cluster's brightest spiral galaxy. After observing the Coma Cluster, astronomer Fritz Zwicky first postulated the existence of dark matter during the 1930s. The massive galaxy Dragonfly 44 discovered in 2015 was found to consist almost entirely of dark matter. Its mass is very similar to that of the Milky Way , but it emits only 1% of
12555-638: The latter two are translations of the Ptolemaic Plokamos , forming the tuft of the constellation Leo and including most of the Flamsteed-designated stars (particularly 12 , 13 , 14 , 16 , 17 , 18 and 21 Comae Berenices ). Al-Sufi included it in Leo. Ulugh Beg , however, regarded Al-Dafira as consisting of two stars, 7 and 23 Comae Berenices . The North American Pawnee people depicted Coma Berenices as ten faint stars on
12690-579: The light emitted by the Milky Way. NGC 4676, sometimes called the Mice Galaxies , is a pair of interacting galaxies 300 million light-years from Earth. Its progenitor galaxies were spiral , and astronomers estimate that they had their closest approach about 160 million years ago. That approach triggered large regions of star formation in both galaxies, with long "tails" of dust, stars and gas. The two progenitor galaxies are predicted to interact significantly at least one more time before they merge into
12825-642: The lunar parallax . If he did not use spherical trigonometry, Hipparchus may have used a globe for these tasks, reading values off coordinate grids drawn on it, or he may have made approximations from planar geometry, or perhaps used arithmetical approximations developed by the Chaldeans. Hipparchus also studied the motion of the Moon and confirmed the accurate values for two periods of its motion that Chaldean astronomers are widely presumed to have possessed before him. The traditional value (from Babylonian System B) for
12960-479: The mean synodic month is 29 days; 31,50,8,20 (sexagesimal) = 29.5305941... days. Expressed as 29 days + 12 hours + 793 / 1080 hours this value has been used later in the Hebrew calendar . The Chaldeans also knew that 251 synodic months ≈ 269 anomalistic months . Hipparchus used the multiple of this period by a factor of 17, because that interval is also an eclipse period, and
13095-515: The monthly motion of the Moon in latitude"), a work mentioned in the Suda . Pliny also remarks that "he also discovered for what exact reason, although the shadow causing the eclipse must from sunrise onward be below the earth, it happened once in the past that the Moon was eclipsed in the west while both luminaries were visible above the earth" (translation H. Rackham (1938), Loeb Classical Library 330 p. 207). Toomer argued that this must refer to
13230-521: The night sky. The patterns of stars seen in asterisms are not necessarily a product of any physical association between the stars, but are rather the result of the particular perspectives of their observations. For example the Summer Triangle is a purely observational physically unrelated group of stars, but the stars of Orion's Belt are all members of the Orion OB1 association and five of
13365-441: The night". Francisco Guerrero, a 20th-century Spanish composer, wrote an orchestral work on the constellation in 1996. In 1999 Irish artist Alice Maher made a series of four oversize drawings, entitled Coma Berenices , of entwining black hair coils. Asterism (astronomy) An asterism is an observed pattern or group of stars in the sky . Asterisms can be any identified pattern or group of stars, and therefore are
13500-424: The number of southern constellations were Johann Bayer (1572–1625) and Nicolas Louis de Lacaille (1713–1762). Bayer had listed twelve figures made out of stars that were too far south for Ptolemy to have seen. Lacaille created 14 new groups, mostly for the area surrounding South Celestial Pole . Many of these proposed constellations have been formally accepted, but the rest have remained as asterisms. In 1928,
13635-539: The observation made on Alexandria 's large public equatorial ring that same day (at 1 hour before noon). Ptolemy claims his solar observations were on a transit instrument set in the meridian. At the end of his career, Hipparchus wrote a book entitled Peri eniausíou megéthous ("On the Length of the Year") regarding his results. The established value for the tropical year , introduced by Callippus in or before 330 BC
13770-419: The observations, rather than a single value for the distance. His results were the best so far: the actual mean distance of the Moon is 60.3 Earth radii, within his limits from Hipparchus's second book. Theon of Smyrna wrote that according to Hipparchus, the Sun is 1,880 times the size of the Earth, and the Earth twenty-seven times the size of the Moon; apparently this refers to volumes , not diameters . From
13905-488: The one given by Archimedes of between 3 + 10 ⁄ 71 (≈ 3.1408) and 3 + 1 ⁄ 7 (≈ 3.1429). Perhaps he had the approximation later used by Ptolemy, sexagesimal 3;08,30 (≈ 3.1417) ( Almagest VI.7). Hipparchus could have constructed his chord table using the Pythagorean theorem and a theorem known to Archimedes. He also might have used the relationship between sides and diagonals of
14040-791: The only such stars in their asterisms or constellations, with Canopus in the Argo Navis asterism south of Sirius, visually east of the Carina Nebula and near the Large Magellanic Cloud (both being first-magnitude deep-sky objects), Achernar in the Eridanus constellation east of Canopus, Fomalhaut in the Southern Fish constellation east of Achernar and Antares in the Scorpius constellation visually near
14175-510: The other way around is debatable. Hipparchus also gave the value for the sidereal year to be 365 + 1 / 4 + 1 / 144 days (= 365.25694... days = 365 days 6 hours 10 min). Another value for the sidereal year that is attributed to Hipparchus (by the physician Galen in the second century AD) is 365 + 1 / 4 + 1 / 288 days (= 365.25347... days = 365 days 6 hours 5 min), but this may be
14310-411: The parallax of the Sun decreases (i.e., its distance increases), the minimum limit for the mean distance is 59 Earth radii—exactly the mean distance that Ptolemy later derived. Hipparchus thus had the problematic result that his minimum distance (from book 1) was greater than his maximum mean distance (from book 2). He was intellectually honest about this discrepancy, and probably realized that especially
14445-563: The period of 4,267 moons is approximately five minutes longer than the value for the eclipse period that Ptolemy attributes to Hipparchus. However, the timing methods of the Babylonians had an error of no fewer than eight minutes. Modern scholars agree that Hipparchus rounded the eclipse period to the nearest hour, and used it to confirm the validity of the traditional values, rather than to try to derive an improved value from his own observations. From modern ephemerides and taking account of
14580-441: The points where the angle intersects the circle. He may have computed this for a circle with a circumference of 21,600 units and a radius (rounded) of 3,438 units; this circle has a unit length for each arcminute along its perimeter. (This was “proven” by Toomer, but he later “cast doubt“ upon his earlier affirmation. Other authors have argued that a circle of radius 3,600 units may instead have been used by Hipparchus. ) He tabulated
14715-403: The positions of Sun and Moon when a solar or lunar eclipse is possible, are explained in Almagest VI.5. Hipparchus apparently made similar calculations. The result that two solar eclipses can occur one month apart is important, because this can not be based on observations: one is visible on the northern and the other on the southern hemisphere—as Pliny indicates—and the latter was inaccessible to
14850-438: The problem of denoting locations on the Earth's surface. Before him a grid system had been used by Dicaearchus of Messana , but Hipparchus was the first to apply mathematical rigor to the determination of the latitude and longitude of places on the Earth. Hipparchus wrote a critique in three books on the work of the geographer Eratosthenes of Cyrene (3rd century BC), called Pròs tèn Eratosthénous geographían ("Against
14985-406: The ratio of the epicycle model ( 3122 + 1 ⁄ 2 : 247 + 1 ⁄ 2 ), which is too small (60 : 4;45 sexagesimal). Ptolemy established a ratio of 60 : 5 + 1 ⁄ 4 . (The maximum angular deviation producible by this geometry is the arcsin of 5 + 1 ⁄ 4 divided by 60, or approximately 5° 1', a figure that is sometimes therefore quoted as the equivalent of
15120-551: The representative figure for astronomy. It is not certain that the figure is meant to represent him. Previously, Eudoxus of Cnidus in the fourth century BC had described the stars and constellations in two books called Phaenomena and Entropon . Aratus wrote a poem called Phaenomena or Arateia based on Eudoxus's work. Hipparchus wrote a commentary on the Arateia —his only preserved work—which contains many stellar positions and times for rising, culmination, and setting of
15255-687: The requirements. The eccentric model he fitted to these eclipses from his Babylonian eclipse list: 22/23 December 383 BC, 18/19 June 382 BC, and 12/13 December 382 BC. The epicycle model he fitted to lunar eclipse observations made in Alexandria at 22 September 201 BC, 19 March 200 BC, and 11 September 200 BC. These figures are due to the cumbersome unit he used in his chord table and may partly be due to some sloppy rounding and calculation errors by Hipparchus, for which Ptolemy criticised him while also making rounding errors. A simpler alternate reconstruction agrees with all four numbers. Hipparchus found inconsistent results; he later used
15390-451: The sacrifice before or after Ptolemy's return; it was suggested that it happened after Ptolemy's return (around March–June or May 245 BC), when Conon presented the asterism jointly with scholar and poet Callimachus during a public evening ceremony. In Callimachus' poem, Aetia (composed around that time), Berenice dedicated her tresses "to all the gods". In Poem 66, the Latin translation by
15525-509: The second and third centuries, coins were made in his honour in Bithynia that bear his name and show him with a globe . Relatively little of Hipparchus's direct work survives into modern times. Although he wrote at least fourteen books, only his commentary on the popular astronomical poem by Aratus was preserved by later copyists. Most of what is known about Hipparchus comes from Strabo 's Geography and Pliny 's Natural History in
15660-586: The seven stars of the Big Dipper are members of the Ursa Major Moving Group . Physical associations, such as the Hyades or Pleiades , can be asterisms in their own right and part of other asterisms at the same time. In many early civilizations, it was common to associate groups of stars in connect-the-dots stick-figure patterns. Some of the earliest records are those of ancient India in
15795-417: The shadow of the Earth is a cone rather than a cylinder as under the first assumption. Hipparchus observed (at lunar eclipses) that at the mean distance of the Moon, the diameter of the shadow cone is 2 + 1 ⁄ 2 lunar diameters. That apparent diameter is, as he had observed, 360 ⁄ 650 degrees. With these values and simple geometry, Hipparchus could determine the mean distance; because it
15930-509: The solstice observation of Meton and his own, there were 297 years spanning 108,478 days; this implies a tropical year of 365.24579... days = 365 days;14,44,51 (sexagesimal; = 365 days + 14 / 60 + 44 / 60 + 51 / 60 ), a year length found on one of the few Babylonian clay tablets which explicitly specifies the System B month. Whether Babylonians knew of Hipparchus's work or
16065-415: The southeastern part of the constellation. Despite its Alpha Bayer designation , the star is dimmer than Beta Comae Berenices, being one of the cases where designation does not correspond to the brightest star. It is a double star , with the spectral classes of F5V and F6V. The star system is 58.1 ± 0.9 light-years from Earth. Gamma Comae Berenices (15 Comae Berenices) is an orange-hued giant star with
16200-513: The stereographic projection is found in Ptolemy 's Planisphere (2nd century AD). Besides geometry, Hipparchus also used arithmetic techniques developed by the Chaldeans . He was one of the first Greek mathematicians to do this and, in this way, expanded the techniques available to astronomers and geographers. There are several indications that Hipparchus knew spherical trigonometry, but
16335-473: The summer solstices in 146 and 135 BC both accurately to a few hours, but observations of the moment of equinox were simpler, and he made twenty during his lifetime. Ptolemy gives an extensive discussion of Hipparchus's work on the length of the year in the Almagest III.1, and quotes many observations that Hipparchus made or used, spanning 162–128 BC, including an equinox timing by Hipparchus (at 24 March 146 BC at dawn) that differs by 5 hours from
16470-468: The synodic and anomalistic periods that Ptolemy attributes to Hipparchus had already been used in Babylonian ephemerides , specifically the collection of texts nowadays called "System B" (sometimes attributed to Kidinnu ). Hipparchus's long draconitic lunar period (5,458 months = 5,923 lunar nodal periods) also appears a few times in Babylonian records . But the only such tablet explicitly dated,
16605-554: The work of Tycho Brahe. Before the 18th century Coma Berenices was known in English by several names, including "Berenice's Bush" and "Berenice's periwig ". The earliest-known English name, "Berenices haire", dates to 1601. By 1702 the constellation was known as Coma Berenices, and appears as such in the 1731 Universal Etymological English Dictionary . Coma Berenices was known to the Akkadians as Ḫegala. In Babylonian astronomy
16740-556: Was 365 + 1 ⁄ 4 days. Speculating a Babylonian origin for the Callippic year is difficult to defend, since Babylon did not observe solstices thus the only extant System B year length was based on Greek solstices (see below). Hipparchus's equinox observations gave varying results, but he points out (quoted in Almagest III.1(H195)) that the observation errors by him and his predecessors may have been as large as 1 ⁄ 4 day. He used old solstice observations and determined
16875-454: Was photometrically observed. Coma Berenices has seven known exoplanets . One, HD 108874 b , has Earth-like insolation . WASP-56 is a sun-like star of spectral type G6 and apparent magnitude 11.48 with a planet 0.6 the mass of Jupiter that has a period of 4.6 days. The Coma Star Cluster represents Berenice's sacrificed tresses and as a naked eye object has been known since antiquity, appearing in Ptolemy's Almagest . It doesn't have
17010-506: Was a Greek astronomer , geographer , and mathematician . He is considered the founder of trigonometry , but is most famous for his incidental discovery of the precession of the equinoxes . Hipparchus was born in Nicaea , Bithynia , and probably died on the island of Rhodes , Greece. He is known to have been a working astronomer between 162 and 127 BC. Hipparchus is considered the greatest ancient astronomical observer and, by some,
17145-572: Was also observed in Alexandria, where the Sun was reported to be obscured 4/5ths by the Moon. Alexandria and Nicaea are on the same meridian. Alexandria is at about 31° North, and the region of the Hellespont about 40° North. (It has been contended that authors like Strabo and Ptolemy had fairly decent values for these geographical positions, so Hipparchus must have known them too. However, Strabo's Hipparchus dependent latitudes for this region are at least 1° too high, and Ptolemy appears to copy them, placing Byzantium 2° high in latitude.) Hipparchus could draw
17280-831: Was announced that a part of it was discovered in a medieval parchment manuscript, Codex Climaci Rescriptus , from Saint Catherine's Monastery in the Sinai Peninsula , Egypt as hidden text ( palimpsest ). Hipparchus also constructed a celestial globe depicting the constellations, based on his observations. His interest in the fixed stars may have been inspired by the observation of a supernova (according to Pliny), or by his discovery of precession, according to Ptolemy, who says that Hipparchus could not reconcile his data with earlier observations made by Timocharis and Aristillus . For more information see Discovery of precession . In Raphael 's painting The School of Athens , Hipparchus may be depicted holding his celestial globe, as
17415-542: Was apparently compiled by Hipparchus, who is consequently now known as "the father of trigonometry". Earlier Greek astronomers and mathematicians were influenced by Babylonian astronomy to some extent, for instance the period relations of the Metonic cycle and Saros cycle may have come from Babylonian sources (see " Babylonian astronomical diaries "). Hipparchus seems to have been the first to exploit Babylonian astronomical knowledge and techniques systematically. Eudoxus in
17550-417: Was calculated by Delambre based on clues in his work. Hipparchus must have lived some time after 127 BC because he analyzed and published his observations from that year. Hipparchus obtained information from Alexandria as well as Babylon , but it is not known when or if he visited these places. He is believed to have died on the island of Rhodes, where he seems to have spent most of his later life. In
17685-404: Was computed for a minimum distance of the Sun, it is the maximum mean distance possible for the Moon. With his value for the eccentricity of the orbit, he could compute the least and greatest distances of the Moon too. According to Pappus, he found a least distance of 62, a mean of 67 + 1 ⁄ 3 , and consequently a greatest distance of 72 + 2 ⁄ 3 Earth radii. With this method, as
17820-423: Was introduced to Western astronomy during the third century BC by Conon of Samos and was further corroborated as a constellation by Gerardus Mercator and Tycho Brahe . It is the only modern constellation named after a historic person. The constellation's major stars are Alpha , Beta , and Gamma Comae Berenices . They form a half square, along the diagonal of which run Berenice's imaginary tresses, formed by
17955-469: Was the first observed type II supernova . SN 2005ap , discovered on 3 March 2005, is the second-brightest-known supernova to date with a peak absolute magnitude of about −22.7. Due to its great distance from Earth (4.7 billion light-years), it was not visible to the naked eye and was discovered telescopically. SN 1979C, discovered in 1979, retained its original X-ray brightness for 25 years despite fading in visible light. Coma Berenices also contains
18090-513: Was the first scientifically observed (underway) type II supernova . FK Comae Berenices is the prototype of an eponymous class of variable stars . The constellation is the radiant of one meteor shower , Coma Berenicids , which has one of the fastest meteor speeds, up to 65 kilometres per second (40 mi/s). Coma Berenices has been recognized as an asterism since the Hellenistic period (or much earlier, according to some authors), and
18225-405: Was the first to be able to measure the geographical latitude and time by observing fixed stars. Previously this was done at daytime by measuring the shadow cast by a gnomon, by recording the length of the longest day of the year or with the portable instrument known as a scaphe . Ptolemy mentions ( Almagest V.14) that he used a similar instrument as Hipparchus, called dioptra , to measure
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