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28-520: Sextans is a medium sized constellation bordering Leo to the north, touching on Hydra to the southwest, and Crater to the southeast. The recommended three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Sex". The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a square. In the equatorial coordinate system ,

56-471: A cave, luring warriors from nearby towns to save the damsel in distress, to their misfortune. The Lion was impervious to any weaponry; thus, the warriors' clubs, swords, and spears were rendered useless against it. Realizing that he must defeat the Lion with his bare hands, Hercules slipped into the Lion's cave and engaged it at close quarters. When the Lion pounced, Hercules caught it in midair, one hand grasping

84-527: A cloud of hydrogen, helium gas, is found in the orbit of two galaxies found within this constellation. M66 is a spiral galaxy that is part of the Leo Triplet, whose other two members are M65 and NGC 3628. It is at a distance of 37 million light-years and has a somewhat distorted shape due to gravitational interactions with the other members of the Triplet, which are pulling stars away from M66. Eventually,

112-575: A period of 310 days and a diameter of 450 solar diameters . The star Wolf 359 (CN Leonis), one of the nearest stars to Earth at 7.8 light-years away, is in Leo. Wolf 359 is a red dwarf of magnitude 13.5; it periodically brightens by one magnitude or less because it is a flare star . Gliese 436 , a faint star in Leo about 33 light-years away from the Sun, is orbited by a transiting Neptune-mass extrasolar planet . The carbon star CW Leo ( IRC +10216 )

140-616: Is a barred spiral galaxy . M105 is about a degree away from the M95/M96 pair; it is an elliptical galaxy of the 9th magnitude, also about 20 million light-years from Earth. NGC 2903 is a barred spiral galaxy discovered by William Herschel in 1784. It is very similar in size and shape to the Milky Way and is located 25 million light-years from Earth. In its core, NGC 2903 has many "hotspots", which have been found to be near regions of star formation . The star formation in this region

168-426: Is a triple star system consisting of two evolved K-type giants of equal mass, with both stars being twice as massive as the Sun. The secondary is itself a single-lined spectroscopic binary consisting of a 0.58  M ☉ companion and itself. The system is located approximately 700 light years away. The outer pair has a separation of 6.8" and both stars take roughly 23,000 years to orbit each other while

196-475: Is the southern celestial hemisphere . In the context of astronomical discussions or writing about celestial cartography , the northern celestial hemisphere may be referred to as the Northern Hemisphere. For celestial mapping , astronomers may conceive the sky like the inside of a sphere divided into two halves by the celestial equator . The Northern Sky or Northern Hemisphere is therefore

224-475: Is the brightest star in the night sky at the infrared N-band (10 μm wavelength). The star SDSS J102915+172927 (Caffau's star) is a population II star in the galactic halo seen in Leo. It is about 13 billion years old, making it one of the oldest stars in the Galaxy. It has the lowest metallicity of any known star. Modern astronomers, including Tycho Brahe in 1602, excised a group of stars that once made up

252-659: Is the location of the field studied by the COSMOS project , undertaken by the Hubble Space Telescope . Sextans B is a fairly bright dwarf irregular galaxy at magnitude 6.6, 4.3 million light-years from Earth . It is part of the Local Group of galaxies. CL J1001+0220 is as of 2016 the most distant-known galaxy cluster at redshift z=2.506, 11.1 billion light-years from Earth. In June 2015, astronomers reported evidence for population III stars in

280-565: Is thought to be due to the presence of the dusty bar, which sends shock waves through its rotation to an area with a diameter of 2,000 light-years. The outskirts of the galaxy have many young open clusters . Leo is also home to some of the largest structures in the observable universe. Some of the structures found in the constellation are the Clowes–Campusano LQG , U1.11 , U1.54 , and the Huge-LQG , which are all large quasar groups ;

308-540: The Cosmos Redshift 7 galaxy (at z = 6.60) found in Sextans. Such stars are likely to have existed in the very early universe (i.e., at high redshift), and may have started the production of chemical elements heavier than hydrogen that are needed for the later formation of planets and life as we know it. Leo (constellation) Leo / ˈ l iː oʊ / is one of the constellations of

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336-482: The Northern Sky , is the northern half of the celestial sphere ; that is, it lies north of the celestial equator . This arbitrary sphere appears to rotate westward around a polar axis due to Earth's rotation . At any given time, the entire Northern Sky is visible from the geographic North Pole , while less of the hemisphere is visible the further south the observer is located. The southern counterpart

364-461: The right ascension coordinates of these borders lie between 09 41 and 10 51 , while the declination coordinates are between +6.43° and −11.7°. Since it is close to the ecliptic plane, the Moon and planets regularly cross the constellation, especially its northeastern corner. John Flamsteed labeled 41 stars for the constellation. Francis Baily intended to give Bayer designations to some of

392-517: The zodiac , between Cancer the crab to the west and Virgo the maiden to the east. It is located in the Northern celestial hemisphere . Its name is Latin for lion , and to the ancient Greeks represented the Nemean Lion killed by the mythical Greek hero Heracles as one of his twelve labors. Its old astronomical symbol is [REDACTED] (♌︎). One of the 48 constellations described by

420-470: The "tuft" of the lion's tail and used them to form the new constellation Coma Berenices (Berenice's hair), although there was precedent for that designation among the ancient Greeks and Romans. Leo contains many bright galaxies ; Messier 65 , Messier 66 , Messier 95 , Messier 96 , Messier 105 , and NGC 3628 are the most famous , the first two being part of the Leo Triplet . The Leo Ring ,

448-414: The 2nd-century astronomer Ptolemy , Leo remains one of the 88 modern constellations today, and one of the most easily recognizable due to its many bright stars and a distinctive shape that is reminiscent of the crouching lion it depicts. Leo contains many bright stars, many of which were individually identified by the ancients. There are nine bright stars that can be easily seen with the naked eye, four of

476-476: The B subsystem takes 1,528 days to circle each other in a relatively eccentric orbit. There are a few notable variable stars , including 25 , 23 Sextantis , and LHS 292 . NGC 3115 , an edge-on lenticular galaxy , is the only noteworthy deep-sky object . It also lies near the ecliptic, which causes the Moon , and some of the planets to occasionally pass through it for brief periods of time. The constellation

504-480: The Lion's forelegs and the other its hind legs, and bent it backwards, breaking its back and freeing the trapped maidens. Zeus commemorated this labor by placing the Lion in the sky. The Roman poet Ovid called it Herculeus Leo and Violentus Leo . Bacchi Sidus (star of Bacchus ) was another of its titles, the god Bacchus always being identified with this animal. However, Manilius called it Jovis et Junonis Sidus (Star of Jupiter and Juno ). As of 2002 ,

532-484: The Sun appears in the constellation Leo from August 10 to September 16. In tropical astrology , the Sun is considered to be in the sign Leo from July 23 to August 22, and in sidereal astrology , from August 16 to September 17. USS Leonis (AK-128) was a United States Navy Crater class cargo ship . [REDACTED] Media related to Leo (constellation) at Wikimedia Commons Northern celestial hemisphere The northern celestial hemisphere , also called

560-558: The constellation was called UR.GU.LA, the "Great Lion"; the bright star Regulus was known as "the star that stands at the Lion's breast." Regulus also had distinctly regal associations, as it was known as the King Star. In Greek mythology , Leo was identified as the Nemean Lion which was killed by Heracles (Hercules to the Romans) during the first of his twelve labours . The Nemean Lion would take women as hostages to its lair in

588-407: The half of the celestial sphere that is north of the celestial equator. Even if this geocentric model is the ideal projection of the terrestrial equator onto the imaginary celestial sphere, the northern and southern celestial hemispheres are not to be confused with descriptions of the terrestrial hemispheres of Earth itself. Of the modern 88 constellations , 43 lie predominantly within

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616-493: The latter being the second largest structure known (see also NQ2-NQ4 GRB overdensity ). The Leonids occur in November, peaking on November 14–15, and have a radiant close to Gamma Leonis . Its parent body is Comet Tempel-Tuttle , which causes significant outbursts every 35 years. The normal peak rate is approximately 10 meteors per hour. The January Leonids are a minor shower that peaks between January 1 and 7. Leo

644-580: The lion's tail and the rest of his body is delineated by Delta Leonis and Theta Leonis . Other named stars in Leo include Mu Leonis , Rasalas (an abbreviation of "Al Ras al Asad al Shamaliyy", meaning "The Lion's Head Toward the South"); and Theta Leonis , Chertan. Leo is also home to a bright variable star , the red giant R Leonis . It is a Mira variable with a minimum magnitude of 10 and normal maximum magnitude of 6; it periodically brightens to magnitude 4.4. R Leonis, 330 light-years from Earth, has

672-462: The nine stars are either first or second magnitude which render this constellation especially prominent. Six of the nine stars also form an asterism known as "The Sickle," which to modern observers may resemble a backwards " question mark ", The sickle is marked by six stars: Epsilon Leonis , Mu Leonis , Zeta Leonis , Gamma Leonis , Eta Leonis , and Alpha Leonis . The rest of the three stars form an isosceles triangle, Beta Leonis (Denebola) marks

700-402: The northern celestial hemisphere, with 28 completely on the northern hemisphere. The other 14 constellations (Aquarius, Aquila, Canis Minor, Cetus, Hydra, Leo, Monoceros, Ophiuchus, Orion, Pisces, Serpens, Sextans, Taurus, and Virgo) lie in some piece on the southern hemisphere. Eridanus has some piece within the northern celestial hemisphere. The pole star of the northern celestial hemisphere

728-418: The outermost stars may form a dwarf galaxy orbiting M66. Both M65 and M66 are visible in large binoculars or small telescopes, but their concentrated nuclei and elongation are only visible in large amateur instruments. M95 and M96 are both spiral galaxies 20 million light-years from Earth. Though they are visible as fuzzy objects in small telescopes, their structure is only visible in larger instruments. M95

756-521: The stars but because none of them were above magnitude 4.5, he left them unlettered. Rather, it was Benjamin Apthorp Gould who lettered some of the stars. He labeled the five brightest stars using Greek letters Alpha (α) to Epsilon (ε) in his Uranometria Argentina . All together, there are 38 stars that are brighter than or equal to apparent magnitude 6.5. Sextans contains a few notable multiple star systems within its boundaries. 35 Sextantis

784-769: Was one of the earliest recognized constellations, with archaeological evidence that the Mesopotamians had a similar constellation as early as 4000 BCE. The Persians called Leo Ser or Shir ; the Turks, Artan ; the Syrians, Aryo ; the Jews, Arye ; the Indians, Simha , all meaning "lion". Some mythologists believe that in Sumeria, Leo represented the monster Humbaba , who was killed by Gilgamesh . In Babylonian astronomy,

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