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{{for|the painting by Carlo Maria Mariani|The Constellation of Leo}}
{{otheruses|Leo (disambiguation)}}
{{Short description|Zodiac constellation straddling the celestial equator}}
{{Infobox Constellation
{{Infobox constellation
| name = Leo
| name = Leo
| abbreviation = Leo
| abbreviation = Leo
| genitive = Leonis
| genitive = Leonis
| pronounce = {{IPAc-en|ˈ|l|iː|oʊ}}, genitive {{IPAc-en|l|iː|ˈ|oʊ|n|ᵻ|s}}
| symbology = the [[Lion]]
| RA = 11
| symbolism = the [[Lion]]
| dec= 15
| RA = {{RA|11}}
| dec= {{DEC|+15}}
| family = [[Zodiac]]
| quadrant = NQ2
| areatotal = 947
| areatotal = 947
| arearank = 12th
| arearank = 12th
| numbermainstars = 9, 15
| numbermainstars = 9, 15
| numberbfstars = 68
| numberbfstars = 92
| numberstarsplanets = 6
| numberstarsplanets = 13
| numberbrightstars = 3
| numberbrightstars = 5
| numbernearbystars = 3
| numbernearbystars = 5
| brighteststarname = [[Regulus]] (α Leo)
| brighteststarname = [[Regulus]] (α Leo)
| starmagnitude = 1.4
| starmagnitude = 1.35
| neareststarname = [[Wolf 359]]
| neareststarname = [[Wolf 359]]
| stardistance = 7.78
| stardistancely = 7.78
| stardistancepc = 2.39
| numbermessierobjects = 5 |
| numbermessierobjects = 5 |
| meteorshowers =[[Leonids]]
| meteorshowers = [[Leonids]]
| bordering =[[Ursa Major]]<br />[[Leo Minor]]<br />[[Lynx (constellation)|Lynx]] (corner)<br />[[Cancer (constellation)|Cancer]]<br />[[Hydra (constellation)|Hydra]]<br />[[Sextans]]<br />[[Crater (constellation)|Crater]]<br />[[Virgo (constellation)|Virgo]]<br />[[Coma Berenices]]
| bordering = [[Ursa Major]]<br />[[Leo Minor]]<br />[[Lynx (constellation)|Lynx]] (corner)<br />[[Cancer (constellation)|Cancer]]<br />[[Hydra (constellation)|Hydra]]<br />[[Sextans]]<br />[[Crater (constellation)|Crater]]<br />[[Virgo (constellation)|Virgo]]<br />[[Coma Berenices]]
| latmax = 90
| latmax = [[North Pole|90]]
| latmin = 65
| latmin = [[65th parallel south|65]]
| month = April
| month = April
| notes =
| notes =
|}}
|}}
'''Leo''' {{IPAc-en|ˈ|l|iː|oʊ}} is one of the [[constellation]]s of the [[zodiac]], between [[Cancer (constellation)|Cancer]] the crab to the west and [[Virgo (constellation)|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 Labours|twelve labors.]] Its old astronomical symbol is [[Image:Leo symbol (fixed width).svg|20px]] (♌︎). One of the 48 constellations described by 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.


==Features==
'''Leo''' ([[International Phonetic Alphabet|IPA]]: {{IPA|/ˈliəʊ/}}, {{lang-la|[[lion]]}}, symbol [[Image:Leo.svg|20px]], {{Unicode|Unicode ♌}}) is a [[constellation]] of the [[zodiac]]. Leo lies between dim [[Cancer (constellation)|Cancer]] to the west and [[Virgo (constellation)|Virgo]] to the east.
[[Image:LeoCC.jpg|thumb|The constellation Leo as it can be seen by the naked eye (the bright object in the center of the picture is the planet Jupiter in March 2004).]]


===Stars===
==Notable features==
{{See also|List of stars in Leo}}
This constellation contains many bright stars, such as [[Regulus]] (α Leonis), the lion's heart; [[Denebola]] (β Leonis); and [[Gamma Leonis|γ<sup>1</sup> Leonis]] (Algieba). Many other fainter stars have been named as well, such as [[Delta Leonis|δ Leo]] (Zosma), [[Theta Leonis|θ Leo]] (Chort), [[Kappa Leonis|κ Leo]] (Al Minliar al Asad ), [[Lambda Leonis|λ Leo]] (Alterf), and ([[Omicron Leonis|ο Leo]] (Subra).
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 the nine stars are either first or second magnitude which render this constellation especially prominent. Six of the nine stars also form an [[asterism (astronomy)|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 [[Regulus|Alpha Leonis]]. The rest of the three stars form an isosceles triangle, [[Beta Leonis]] (Denebola) marks the lion's tail and the rest of his body is delineated by [[Delta Leonis]] and [[Theta Leonis]].{{sfn|Ridpath|Tirion|2001|pp=166-167}}
{{flowlist}}
* [[Regulus]], designated [[Alpha Leonis (star)|Alpha Leonis]], is a blue-white [[main-sequence]] star of magnitude 1.34, 77.5 light-years from Earth. It is a [[double star]] divisible in binoculars, with a secondary of magnitude 7.7. Its traditional name (Regulus) means "the little king".
* [[Beta Leonis]], called Denebola, is at the opposite end of the constellation to Regulus. It is a blue-white star of magnitude 2.23, 36 light-years from Earth. The name Denebola means "the lion's tail".
* Algieba, [[Gamma Leonis]], is a [[binary star]] with a third optical component; the primary and secondary are divisible in small telescopes and the tertiary is visible in binoculars. The primary is a gold-yellow [[giant star]] of magnitude 2.61 and the secondary is similar but at magnitude 3.6; they have a period of 600 years and are 126 light-years from Earth. The unrelated tertiary, [[40 Leonis]], is a yellow-tinged star of magnitude 4.8. Its traditional name, Algieba, means "the forehead".
* [[Delta Leonis]], called Zosma, is a blue-white star of magnitude 2.58, 58 light-years from Earth.
{{endflowlist}}
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.<ref>{{cite web|title=Star Names|first=R. H. |last=Allen|url=https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Leo*.html}}</ref><ref name="IAU-CSN">{{cite web |url=https://www.iau.org/public/themes/naming_stars/#n4 | title=List of IAU-approved Star Names |access-date=24 January 2022}}</ref>


{| class="wikitable sortable"
Regulus, η Leonis, and γ Leonis, together with the fainter stars [[Zeta Leonis|ζ Leo]] (Adhafera), [[Mu Leonis|μ Leo]] (Ras Elased Borealis), and [[Epsilon Leonis|ε Leo]] (Ras Elased Australis), make up the [[asterism (astronomy)|asterism]] known as the Sickle. These stars represent the head and the mane of the lion.
|+Brightest Stars of Leo
|-
!Proper Name
!Bayer Designation
!Light Years
!Apparent Magnitude
|-
|Regulus
|[[α Leonis]]
|style="text-align: right;"|79
|style="text-align: right;"|1.35
|-
|Denebola
|[[β Leonis]]
|style="text-align: right;"|36
|style="text-align: right;"|2.14
|-
|Algieba
|[[γ Leonis]]
|style="text-align: right;"|130
|style="text-align: right;"|2.08
|-
|Zosma
|[[δ Leonis]]
|style="text-align: right;"|58
|style="text-align: right;"|2.56
|-
|Algenubi
|[[ε Leonis]]
|style="text-align: right;"|247
|style="text-align: right;"|2.98
|-
|Adhafera
|[[ζ Leonis]]
|style="text-align: right;"|274
|style="text-align: right;"|3.33
|-
|Al Jabhah
|[[η Leonis]]
|style="text-align: right;"|1,270
|style="text-align: right;"|3.49
|-
|Chertan
|[[θ Leonis]]
|style="text-align: right;"|165
|style="text-align: right;"|3.32
|-
|Rasalas
|[[μ Leonis]]
|style="text-align: right;"|124
|style="text-align: right;"|3.88
|}
[[File:Sidney Hall - Urania's Mirror - Leo Major and Leo Minor.jpg|thumb|left|Leo, with Leo Minor above, as depicted in ''[[Urania's Mirror]]'', a set of constellation cards published in London c.1825]]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 a period of 310 days and a diameter of 450 [[solar diameter]]s.{{sfn|Ridpath|Tirion|2001|pp=166-168}}


The star [[Wolf 359]] (CN Leonis), one of the [[List of nearest stars|nearest stars]] to Earth at 7.8 [[light-year]]s 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]].{{sfn|Ridpath|Tirion|2001|pp=166-168}} [[Gliese 436]], a faint star in Leo about 33 light-years away from the Sun, is orbited by a transiting Neptune-mass [[extrasolar planet]].<ref>{{cite news|url=https://www.theglobeandmail.com/servlet/story/RTGAM.20040831.wplanet20831a/BNStory/specialScienceandHealth |title=Astronomers discover smallest "exoplanets" yet |location=Toronto |url-status=dead |archive-url=https://web.archive.org/web/20090116080659/http://www.theglobeandmail.com/servlet/story/RTGAM.20040831.wplanet20831a/BNStory/specialScienceandHealth/ |archive-date=January 16, 2009 }}</ref>
A former asterism representing the tuft of the lion's tail was made its own constellation by [[Ptolemy III]] in 240 BC. It was given the name [[Coma Berenices]].

The star [[Wolf 359]], one of the [[List of nearest stars|nearest stars]] to Earth (7.7 [[light-year]]s), is in Leo. [[Gliese 436]], a faint star in Leo about 33 light years away from the Sun, is orbited by one of the smallest [[extrasolar planet]]s ever found.<ref>http://www.theglobeandmail.com/servlet/story/RTGAM.20040831.wplanet20831a/BNStory/specialScienceandHealth/</ref>


The [[carbon star]] CW Leo ([[IRC +10216]]) is the brightest star in the night sky at the infrared N-band (10 μm wavelength).
The [[carbon star]] CW Leo ([[IRC +10216]]) 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.
==Notable deep sky objects==
Leo contains many bright [[galaxy|galaxies]], of which the twins ([[Spiral Galaxy M65]], [[Spiral Galaxy M66]]) and ([[Spiral Galaxy M95]], [[Spiral Galaxy M96]]) are the most famous.


Modern astronomers, including [[Tycho Brahe]] in 1602, excised a group of stars that once made up 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.<ref>L. Phil Simpson (Springer 2012) Guidebook to the Constellations: Telescopic Sights, Tales, and Myths, p. 235 ({{ISBN|9781441969415}}).</ref>
==History==
===Etymology===
Early Hindu astronomers knew it as ''Asleha'' and as ''Sinha'', the [[Tamil language|Tamil]] ''Simham'' but later, influenced by Greece and Rome, as ''Leya'' or ''Leyaya'', from the word Leo, as the Romans commonly called it.


===Deep-sky objects===
[[Ovid]] wrote it as ''Herculeus Leo'' and ''Violentus Leo''. ''Bacchi Sidus'' (Star of [[Bacchus]]) was another of its titles, the god always being identified with this animal, and its shape the one often adopted by him in his numerous transformations, while a lion's skin was his frequent dress. But [[Marcus Manilius|Manilius]] had it ''Jovis et Junonis Sidus'' (Star of [[Jupiter (mythology)|Jove]] and [[Juno (mythology)|Juno]]), as being under the guardianship of these deities, perhaps appropriately considering its regal character, especially that of its lucida.
Leo contains many bright [[galaxy|galaxies]]; [[Messier 65]], [[Messier 66]], [[Messier 95]], [[Messier 96]], [[Messier 105]], and [[NGC 3628]] are the most famous{{citation needed|date=November 2022}}, the first two being part of the [[Leo Triplet]].


The [[Leo Ring]], a cloud of hydrogen, helium gas, is found in the orbit of two galaxies found within this constellation.[[File:Phot-33c-03-fullres.jpg|thumbnail|left|Messier 66]] 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, the outermost stars may form a dwarf galaxy orbiting M66.<ref name="objects">{{cite book |title = 300 Astronomical Objects: A Visual Reference to the Universe |last1 = Wilkins |first1 = Jamie |last2 = Dunn |first2 = Robert |publisher = Firefly Books |location = Buffalo, New York |date = 2006 |isbn = 978-1-55407-175-3}}</ref> 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.{{sfn|Ridpath|Tirion|2001|pp=166-168}}
The Persians called it ''Ser'' or ''Shir''; the Turks, ''Artan''; the Syrians, ''Aryo''; the Jews, ''Arye''; the Indians, "Sher"; and the Babylonians, ''Aru'' &mdash; all meaning a lion. In Euphratean astronomy it was additionally known as ''Gisbar-namru-sa-pan'', variously translated, but by [[Bertin]], as the ''Shining Disc which precedes Bel'', "''Bel''" being our [[Ursa Major]], or in some way intimately connected therewith.


[[File: A Horseshoe Einstein Ring from Hubble.JPG|thumb|The notable [[gravitational lens]] known as the [[Cosmic Horseshoe]]]]
===Symbol===
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 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. {{sfn|Ridpath|Tirion|2001|pp=166-168}}
[[Image:Leo constellation drawing.png|thumb|220px|right|Hevelius' drawing of Leo, 1690]]
The adoption of this animal's form for the zodiac sign has been attributed to the fact that when the Sun was among its stars in midsummer the lions of the desert left their accustomed haunts for the banks of the [[Nile]], where they could find relief from the heat in the waters of the [[inundation]]. [[Pliny the Elder|Pliny]] wrote that the [[Egyptians]] worshipped the stars of Leo because the rise of their great river was coincident with the Sun's entrance among them. For the same reason the [[Sphinx]] is said to have been sculpted with Leo's body and the head of the adjacent Virgo, although Egyptologists maintain that this head represented one of the early kings, or the god [[Harmachis]].


[[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 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 cluster]]s.<ref name=" objects"/>
Distinct reference is made to Leo in an inscription of the walls of the [[Ramesseum]] at [[Thebes (Egypt)|Thebes]], which, like the Nile temples generally, was adorned with the animal's bristles, while on the planisphere of [[Dendera]] its figure is shown standing on an outstretched serpent. The Egyptian stellar Lion, however, comprised only a part of ours, and in the earliest records some of its stars were shown as a knife, as they now are as a sickle. [[Kircher]] gave its title there as ''Πιμεντεκεων'', ''Cubitus Nili''.


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 group]]s; the latter being the second largest structure known<ref>{{cite news|date= 11 January 2013|last=Prostak|first=Sergio|title=Universe's Largest Structure Discovered|url=http://www.sci-news.com/astronomy/article00818.html|publisher=scinews.com|access-date=15 January 2013}}</ref> (see also [[NQ2-NQ4 GRB overdensity]]).
The astrological symbol [[Image:Leo.svg|20px]] has been supposed to portray the animal's mane, but it also might be the animal's tail. [[Gaius Julius Hyginus]]'s writing published in [[1488]] and [[Albumasar]]'s in [[1489]] showing this latter member of extraordinary length, twisting between the hind legs and over the back, Hyginus's manuscript properly locating the star [[Denebola]] in the end. But the ''International Dictionary'' says that this symbol is a corruption of the initial letter of ''Λεων'' (''Leon''). [[Félix Lajard]]'s ''Cultes de Mithra'' mentions the hieroglyph of Leo as among the symbols of [[Mithraic worship]], but how their Lion agreed, if at all, with ours is not known.


===Meteor showers===
==Mythology==
The [[Leonids]] occur in November, peaking on November 14–15, and have a [[radiant (meteor shower)|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.{{sfn|Ridpath|Tirion|2001|pp=166-167}}
In [[Greek mythology]], it was identified as the [[Nemean Lion]] (and may have been a source of the tale) which was killed by [[Hercules]] during one of his [[The Twelve Labours|twelve labours]], and subsequently put into the sky.


The [[January Leonids]] are a minor shower that peaks between January 1 and 7.<ref>{{cite journal |journal = Sky & Telescope |date = September 2011 |last = Jenniskens |first = Peter |page = 24 |title = Mapping Meteoroid Orbits: New Meteor Showers Discovered}}</ref>
===Astrology===
{{main|Leo (astrology)}}
The Western [[astrological sign]] Leo of the [[tropical zodiac]] ([[July 23]] &ndash; [[August 22]]) differs from the astronomical constellation and the Hindu astrological sign of the [[Sidereal astrology|sidereal zodiac]] ([[August 10]] &ndash; [[September 15]]).


==History and mythology==
In some cosmologies, Leo is associated with the [[classical element]] [[Classical element/Fire|Fire]], and thus called a Fire Sign (with [[Aries (astrology)|Aries]] and [[Sagittarius (astrology)|Sagittarius]]). Leo is also one of the Fixed signs (along with [[Taurus (astrology)|Taurus]], [[Scorpius|Scorpio]], and [[Aquarius (astrology)|Aquarius]]).
[[File:F17.v. Leo -NLW MS 735C.png|thumb|Leo from a western scientific manuscript, c.1000]]
Leo was one of the earliest recognized constellations, with archaeological evidence that the Mesopotamians had a similar constellation as early as 4000 BCE.<ref name="pasachoff"/> The Persians called Leo ''Ser'' or ''Shir''; the Turks, ''Artan''; the Syrians, ''Aryo''; the Jews, ''Arye''; the Indians, ''Simha'', all meaning "lion".
[[File:Hercules and Nemean Lion Stamp.jpg|thumbnail|Cypriot stamp depicting a mosaical image of the encounter between Hercules and Leo, the Nemean Lion]]
Some mythologists believe that in Sumeria, Leo represented the monster [[Humbaba]], who was killed by [[Gilgamesh]].<ref>Tamra Andrews (Oxford University Press 2000) Dictionary of Nature Myths: Legends of the Earth, Sea, and Sky ({{ISBN|9780195136777}}).</ref>


In Babylonian astronomy, 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.<ref>''Babylonian Star-lore'' by Gavin White, Solaria Publications, 2008 page 140, {{ISBN|978-0955903700}}</ref>
It is the [[domicile (astrology)|domicile]] of the [[Sun]]. The Egyptian pharaoh [[Nechepso]], and his priest [[Petosiris]], taught that at the creation of the world the Sun rose here near [[Denebola]], and hence Leo was ''Domicilium Solis'', the emblem of fire and heat, and the "House of the Sun".


In [[Greek mythology]], Leo was identified as the [[Nemean lion|Nemean Lion]] which was killed by [[Heracles]] (Hercules to the Romans) during the first of his [[Labours of Hercules|twelve labours]].<ref name="pasachoff">{{cite book |title=Stars and Planets |last = Pasachoff |first = Jay M. |location = Boston, Massachusetts |publisher = Houghton Mifflin|isbn=9780395537596 |date = 2006}}</ref>{{sfn|Ridpath|Tirion|2001|pp=166-167}} The Nemean Lion would take women as hostages to its lair in a cave, luring warriors from nearby towns to save the damsel in distress, to their misfortune.<ref name=Parker>{{cite book|title=Mythology: Myths, Legends and Fantasies|date=2007|publisher=[[Struik]]|isbn=9781770074538|pages=121–122|editor=Janet Parker|display-editors=etal}}</ref> 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.<ref name=Parker /> When the Lion pounced, Hercules caught it in midair, one hand grasping the Lion's forelegs and the other its hind legs, and bent it backwards, breaking its back and freeing the trapped maidens.<ref name=Parker /> Zeus commemorated this labor by placing the Lion in the sky.<ref name=Parker />
Each astrological sign is assigned a part of the body, viewed as the seat of its power. Leo rules the heart and spine.


The Roman poet [[Ovid]] called it ''Herculeus Leo'' and ''Violentus Leo''. ''Bacchi Sidus'' (star of [[Dionysus|Bacchus]]) was another of its titles, the god [[Dionysus|Bacchus]] always being identified with this animal. However, [[Marcus Manilius|Manilius]] called it ''Jovis et Junonis Sidus'' (Star of [[Jupiter (mythology)|Jupiter]] and [[Juno (mythology)|Juno]]).
===Alchemy===
In the symbolism of [[alchemy]], Leo denoted the absorption or assimilation of one substance by another.


==Astrology==
==Graphic visualization==
{{Main|Leo (astrology)}}
[[Image:Leo_constellation_map_visualization.PNG|thumb|300px|right|Diagram of an alternate way to connect the stars of the constellation Leo. The lion is shown walking.]]
{{As of|2002}}, the Sun appears in the constellation Leo from August 10 to September 16.<ref>Jean Meeus, "Zodiacal Constellations", in: ''More Mathematical Astronomy Morsels'' (Richmond: Willmann-Bell Inc., 2002), pp. 327-333. Dates in other years can vary by one day due to the insertion of a [[leap day]].</ref> In [[tropical astrology]], the Sun is considered to be in the sign [[Leo (astrology)|Leo]] from July 23 to August 22, and in [[sidereal astrology]], from August 16 to September 17.
The stars of the constellation Leo can be connected in an alternative way, which graphically shows a [[lion]] walking.


{{Clear}}
The stars [[delta Leonis]], [[gamma Leonis]], [[eta Leonis]], and [[theta Leonis]] form the [[body]] of the lion, with gamma Leonis being of the second magnitude and delta Leonis and theta Leonis being of the third magnitude.


==Namesakes==
The stars gamma Leonis, [[zeta Leonis]], [[mu Leonis]], [[epsilon Leonis]], and [[eta Leonis]] form the lion's [[neck]], with epsilon Leonis being of the third magnitude.
[[USS Leonis (AK-128)]] was a [[United States Navy]] [[Crater class cargo ship]].

The stars mu Leonis, [[kappa Leonis]], [[lambda Leonis]], and epsilon Leonis form the [[head]] of the lion.

The stars delta Leonis and [[beta Leonis]] form the lion's [[tail]]: beta Leonis, also known as [[Denebola]], is the bright tip of the tail with a magnitude of two.

The stars theta Leonis, [[iota Leonis]], and [[sigma Leonis]] form the left hind [[leg]] of the lion, with sigma Leonis being the foot. The stars theta Leonis and [[rho Leonis]] form the right hind leg, with rho Leonis being the foot.

The stars eta Leonis and [[alpha Leonis]] form the left front foot, with alpha Leonis, also known as [[Regulus]], being the bright foot of magnitude one. The stars eta Leonis and [[omicron Leonis]] form the right front foot of the Lion.<ref>H. A. Rey, ''The Stars &mdash; A New Way To See Them''. Enlarged World-Wide Edition. Houghton Mifflin, Boston, 1997. ISBN 0-395-24830-2.</ref>


==See also==
==See also==
* [[Leo (Chinese astronomy)]]
*[[Constellations in popular culture#Leo|Leo in popular culture]]
*[[List of stars in Leo]]


==References==
==References==
{{Reflist}}
<references/>
*''Star Names: Their Lore and Meaning'', by Richard Allen Hinckley, Dover. ISBN 0-486-21079-0
* ''Star Names: Their Lore and Meaning'', by Richard Allen Hinckley, Dover. {{ISBN|0-486-21079-0}}
* {{citation |title = Stars and Planets Guide |last1 = Ridpath |first1 = Ian |last2 = Tirion |first2 = Wil |year = 2001 |publisher = Princeton University Press |isbn = 0-691-08913-2}}
*''Dictionary of Symbols'', by Carl G. Liungman, W. W. Norton & Company. ISBN 0-393-31236-4
* Ian Ridpath and Wil Tirion (2007). ''Stars and Planets Guide'', Collins, London. {{ISBN|978-0-00-725120-9}}. Princeton University Press, Princeton. {{ISBN|978-0-691-13556-4}}.

* ''Dictionary of Symbols'', by Carl G. Liungman, W. W. Norton & Company. {{ISBN|0-393-31236-4}}
== External links ==
{{Commons|Leo}}
* [http://www.allthesky.com/constellations/leo/ The Deep Photographic Guide to the Constellations: Leo]
* [http://wikisky.org/?object=Leo&zoom=2 '''WIKISKY.ORG:''' Leo constellation]


==External links==
*[http://astrojan.nhely.hu/leo.htm The clickable Leo]
*[https://iconographic.warburg.sas.ac.uk/category/vpc-taxonomy-017063 The Warburg Institute Iconographic Database (medieval and early-modern images of Leo)]
*[https://stardate.org/astro-guide/leo-lion-0 Information from StarDate Online]
*[http://www.ianridpath.com/startales/leo.html Ian Ridpath's Star Tales – Leo]
{{Commons category-inline|Leo (constellation)}}
{{Stars of Leo}}
{{Constellations}}
{{Zodiac}}
{{Zodiac}}
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{{Sky|11|00|00|+|15|00|00|10}}
[[Category:Leo constellation|*]]
[[Category:Constellations]]
[[Category:Western astrology]]


{{DEFAULTSORT:Leo (Constellation)}}
[[ast:Lleo]]
[[Category:Leo (constellation)| ]]
[[bg:Лъв (съзвездие)]]
[[Category:Constellations listed by Ptolemy]]
[[ca:Lleó (constel·lació)]]
[[Category:Equatorial constellations]]
[[cs:Lev (souhvězdí)]]
[[co:Leo]]
[[da:Løven (stjernebillede)]]
[[de:Löwe (Sternbild)]]
[[el:Λέων (αστερισμός)]]
[[es:Leo]]
[[eo:Leono (konstelacio)]]
[[fr:Lion (constellation)]]
[[ga:An Leon]]
[[ko:사자자리]]
[[hr:Lav (zviježđe)]]
[[io:Leono (stelaro)]]
[[id:Leo]]
[[it:Leone (costellazione)]]
[[he:אריה (קבוצת כוכבים)]]
[[ka:ლომი (ზოდიაქო)]]
[[la:Leo (sidus)]]
[[lt:Liūtas (astronomija)]]
[[hu:Oroszlán]]
[[nl:Leeuw (sterrenbeeld)]]
[[ja:しし座]]
[[pl:Lew (gwiazdozbiór)]]
[[pt:Leo]]
[[ro:Leul (constelaţie)]]
[[ru:Лев (созвездие)]]
[[sk:Súhvezdie Lev]]
[[fi:Leijona (tähdistö)]]
[[sv:Lejonet]]
[[th:กลุ่มดาวสิงโต]]
[[vi:Sư Tử]]
[[tr:Leo (takımyıldız)]]
[[uk:Лев (сузір'я)]]
[[zh:狮子座]]

Latest revision as of 20:13, 23 August 2024

For the painting by Carlo Maria Mariani, see The Constellation of Leo.
Leo
Constellation
Leo
List of stars in Leo
AbbreviationLeo
GenitiveLeonis
Pronunciation/ˈliːoʊ/, genitive /liːˈoʊnɪs/
Symbolismthe Lion
Right ascension11h
Declination+15°
QuadrantNQ2
Area947 sq. deg. (12th)
Main stars9, 15
Bayer/Flamsteed
stars		92
Stars with planets13
Stars brighter than 3.00m5
Stars within 10.00 pc (32.62 ly)5
Brightest starRegulus (α Leo) (1.35m)
Messier objects5
Meteor showersLeonids
Bordering
constellations		Ursa Major
Leo Minor
Lynx (corner)
Cancer
Hydra
Sextans
Crater
Virgo
Coma Berenices
Visible at latitudes between +90° and −65°.
Best visible at 21:00 (9 p.m.) during the month of April.

Leo /ˈliːoʊ/ is one of the constellations of 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 (♌︎). One of the 48 constellations described by 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.

Features

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The constellation Leo as it can be seen by the naked eye (the bright object in the center of the picture is the planet Jupiter in March 2004).

Stars

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See also: List of stars in Leo

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 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 the lion's tail and the rest of his body is delineated by Delta Leonis and Theta Leonis.[1]

  • Regulus, designated Alpha Leonis, is a blue-white main-sequence star of magnitude 1.34, 77.5 light-years from Earth. It is a double star divisible in binoculars, with a secondary of magnitude 7.7. Its traditional name (Regulus) means "the little king".
  • Beta Leonis, called Denebola, is at the opposite end of the constellation to Regulus. It is a blue-white star of magnitude 2.23, 36 light-years from Earth. The name Denebola means "the lion's tail".
  • Algieba, Gamma Leonis, is a binary star with a third optical component; the primary and secondary are divisible in small telescopes and the tertiary is visible in binoculars. The primary is a gold-yellow giant star of magnitude 2.61 and the secondary is similar but at magnitude 3.6; they have a period of 600 years and are 126 light-years from Earth. The unrelated tertiary, 40 Leonis, is a yellow-tinged star of magnitude 4.8. Its traditional name, Algieba, means "the forehead".
  • Delta Leonis, called Zosma, is a blue-white star of magnitude 2.58, 58 light-years from Earth.

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.[2][3]

Brightest Stars of Leo
Proper Name Bayer Designation Light Years Apparent Magnitude
Regulus α Leonis 79 1.35
Denebola β Leonis 36 2.14
Algieba γ Leonis 130 2.08
Zosma δ Leonis 58 2.56
Algenubi ε Leonis 247 2.98
Adhafera ζ Leonis 274 3.33
Al Jabhah η Leonis 1,270 3.49
Chertan θ Leonis 165 3.32
Rasalas μ Leonis 124 3.88
Leo, with Leo Minor above, as depicted in Urania's Mirror, a set of constellation cards published in London c.1825

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 a period of 310 days and a diameter of 450 solar diameters.[4]

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.[4] Gliese 436, a faint star in Leo about 33 light-years away from the Sun, is orbited by a transiting Neptune-mass extrasolar planet.[5]

The carbon star CW Leo (IRC +10216) 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 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.[6]

Deep-sky objects

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Leo contains many bright galaxies; Messier 65, Messier 66, Messier 95, Messier 96, Messier 105, and NGC 3628 are the most famous[citation needed], the first two being part of the Leo Triplet.

The Leo Ring, a cloud of hydrogen, helium gas, is found in the orbit of two galaxies found within this constellation.

Messier 66

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, the outermost stars may form a dwarf galaxy orbiting M66.[7] 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.[4]

The notable gravitational lens known as the Cosmic Horseshoe

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 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. [4]

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 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.[7]

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; the latter being the second largest structure known[8] (see also NQ2-NQ4 GRB overdensity).

Meteor showers

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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.[1]

The January Leonids are a minor shower that peaks between January 1 and 7.[9]

History and mythology

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Leo from a western scientific manuscript, c.1000

Leo was one of the earliest recognized constellations, with archaeological evidence that the Mesopotamians had a similar constellation as early as 4000 BCE.[10] The Persians called Leo Ser or Shir; the Turks, Artan; the Syrians, Aryo; the Jews, Arye; the Indians, Simha, all meaning "lion".

Cypriot stamp depicting a mosaical image of the encounter between Hercules and Leo, the Nemean Lion

Some mythologists believe that in Sumeria, Leo represented the monster Humbaba, who was killed by Gilgamesh.[11]

In Babylonian astronomy, 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.[12]

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.[10][1] The Nemean Lion would take women as hostages to its lair in a cave, luring warriors from nearby towns to save the damsel in distress, to their misfortune.[13] 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.[13] When the Lion pounced, Hercules caught it in midair, one hand grasping the Lion's forelegs and the other its hind legs, and bent it backwards, breaking its back and freeing the trapped maidens.[13] Zeus commemorated this labor by placing the Lion in the sky.[13]

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).

Astrology

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Main article: Leo (astrology)

As of 2002, the Sun appears in the constellation Leo from August 10 to September 16.[14] 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.

Namesakes

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USS Leonis (AK-128) was a United States Navy Crater class cargo ship.

See also

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References

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  1. ^ a b c Ridpath & Tirion 2001, pp. 166–167.
  2. ^ Allen, R. H. "Star Names".
  3. ^ "List of IAU-approved Star Names". Retrieved 24 January 2022.
  4. ^ a b c d Ridpath & Tirion 2001, pp. 166–168.
  5. ^ "Astronomers discover smallest "exoplanets" yet". Toronto. Archived from the original on January 16, 2009.
  6. ^ L. Phil Simpson (Springer 2012) Guidebook to the Constellations: Telescopic Sights, Tales, and Myths, p. 235 (ISBN 9781441969415).
  7. ^ a b Wilkins, Jamie; Dunn, Robert (2006). 300 Astronomical Objects: A Visual Reference to the Universe. Buffalo, New York: Firefly Books. ISBN 978-1-55407-175-3.
  8. ^ Prostak, Sergio (11 January 2013). "Universe's Largest Structure Discovered". scinews.com. Retrieved 15 January 2013.
  9. ^ Jenniskens, Peter (September 2011). "Mapping Meteoroid Orbits: New Meteor Showers Discovered". Sky & Telescope: 24.
  10. ^ a b Pasachoff, Jay M. (2006). Stars and Planets. Boston, Massachusetts: Houghton Mifflin. ISBN 9780395537596.
  11. ^ Tamra Andrews (Oxford University Press 2000) Dictionary of Nature Myths: Legends of the Earth, Sea, and Sky (ISBN 9780195136777).
  12. ^ Babylonian Star-lore by Gavin White, Solaria Publications, 2008 page 140, ISBN 978-0955903700
  13. ^ a b c d Janet Parker; et al., eds. (2007). Mythology: Myths, Legends and Fantasies. Struik. pp. 121–122. ISBN 9781770074538.
  14. ^ Jean Meeus, "Zodiacal Constellations", in: More Mathematical Astronomy Morsels (Richmond: Willmann-Bell Inc., 2002), pp. 327-333. Dates in other years can vary by one day due to the insertion of a leap day.
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Media related to Leo (constellation) at Wikimedia Commons


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