Leo

Leo

Constellation
List of stars in Leo
Abbreviation	Leo
Genitive	Leonis
Pronunciation	/ˈliːoʊ/, genitive /liːˈoʊnɨs/
Symbolism	the Lion
Right ascension	11 h
Declination	+15°
Quadrant	NQ2
Area	947 sq. deg. (12th)
Main stars	9, 15
Bayer/Flamsteed stars	92
Stars with planets	13
Stars brighter than 3.00m	5
Stars within 10.00 pc (32.62 ly)	5
Brightest star	Regulus (α Leo) (1.35m)
Nearest star	Wolf 359 (7.78 ly, 2.39 pc)
Messier objects	5
Meteor showers	Leonids
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. Its name is Latin for lion. Its symbol is ( ♌). Leo lies between dim Cancer to the west and Virgo to the east.

Notable features

Stars

Leo contains many bright stars, such as Regulus (α Leonis); the lion's tail, Denebola (β Leonis); and γ¹ Leonis (Algieba). Many other fainter stars have been named as well, such as δ Leo (Zosma), θ Leo (Chort), κ Leo (Al Minliar al Asad), λ Leo (Alterf), and ο Leo (Subra).

Regulus, Al Jabbah, and Algieba, together with the fainter stars ζ Leo (Adhafera), μ Leo (Ras Elased Borealis), and ε Leo (Ras Elased Australis), make up the asterism known as the Sickle. These stars represent the head and the mane of the lion.

The star Wolf 359, one of the nearest stars to Earth (7.78 light-years), is in Leo. Gliese 436, a faint star in Leo about 33 light years away from the Sun, is orbited by a transiting Neptune-mass extrasolar planet.^[1]

The carbon star CW Leo (IRC +10216) is the brightest star in the night sky at the infrared N-band (10 μm wavelength).

Deep-sky objects

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, a cloud of hydrogen and helium gas, is found in 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, the outermost stars may form a dwarf galaxy orbiting M66.^[2]

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.^[2]

History and mythology

Leo was one of the earliest recognized constellations, as there is archaeological evidence that the Mesopotamians had a similar constellation as early as 4000 BCE.^[3]The Persians called Leo Ser or Shir; the Turks, Artan; the Syrians, Aryo; the Jewish, Arye; the Indians, Simha, all meaning "lion". In Babylonian astronomy the constellation was called UR.GU.LA - the 'Great Lion'; the bright star, Regulus, that stands at the Lion's breast also had distinctly regal associations as it was known as the King Star.^[4]

In Greek mythology, Leo was identified as the Nemean Lion which was killed by Hercules during one of his twelve labours, and subsequently put into the sky.^[3]

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).

Early Hindu astronomers knew it as Asleha and as Sinha, the Tamil Simham.

Astrology

As of 2002^[update], the Sun appeared in the constellation Leo from August 10 to Sept 10. In tropical astrology, the Sun is considered to be in the sign Leo from July 23 to August 23, and in sidereal astrology, from August 16 to September 15.

Visualizations

Leo, with Leo Minor above, as depicted in Urania's Mirror, a set of constellation cards published in London c.1825.

Leo is commonly represented as if the sickle-shaped asterism of stars is the back of the Lion's head.

Diagram of H.A. Rey's alternative way to connect the stars of the constellation Leo. The lion is shown walking.

H.A. Rey has suggested an alternative way to connect the stars, which graphically shows a lion walking. 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. 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. The stars mu Leonis, kappa Leonis, lambda Leonis, and epsilon Leonis form the head of the lion. 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 mark the lion's heart, with alpha Leonis, also known as Regulus, being the bright star of magnitude one. The stars eta Leonis and omicron Leonis form the right front foot of the Lion.^[5]

Namesakes

USS Leonis (AK-128) was a United States Navy Crater class cargo ship named after the Latin version of this constellation name.

Citations

References

• Star Names: Their Lore and Meaning, by Richard Allen Hinckley, Dover. ISBN 0-486-21079-0
• 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

Media related to Leo (constellation) at Wikimedia Commons

Observer links

• The Deep Photographic Guide to the Constellations: Leo
• Information from Windows to the Universe
• Star Map of Leo and Information from Students for Exploration and Development of Space
• Information about Leo from Chris Dolan
• Information from StarDate Online
• Leo's skymap and information from Gary Madison
• Star Map of Leo and basic information
• Pictures, Sky Map and detailed information from StarrySkies

Science

• New planet discovery in Leo's constellation

Myths

• Star Tales – Leo
• Myth Info from comfychair.org
• Myth Info from TheGreekGods.org
• Myth Info from ColdWater Schools
• Myth Info from Star Watch GeoCity
• Myth Info from heavens-above.com

v t e The Zodiac
Astrology | Signs of the Zodiac
Aries													Taurus													Gemini													Cancer													Leo													Virgo													Libra													Scorpio													Sagittarius													Capricorn													Aquarius													Pisces
Astronomy | Constellations of the Ecliptic
Aries												Taurus												Gemini												Cancer												Leo												Virgo												Libra												Scorpius												Ophiuchus												Sagittarius												Capricornus												Aquarius												Pisces
See also: Ecliptic coordinates Precession of the equinoxes 13-sign zodiac Zodiacal light

Coordinates: 11^h 00^m 00^s, +15° 00′ 00″