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Leo, The Lion Constellation

Leo Constellation Star Map

Leo (Pronounciation:Lee-o, Abbrev:Leo, Latin:Leonis) is a constellation, one of 88 constellations that the night sky is divided into. The sky is not divided up equally between the constellations. Leo takes up 946.964 sq. degrees of the night sky which equates to 2.3% of the night sky. Leo is the 12th largest in terms of size in the night sky.

The constellation name means The Lion . The constellation is one of the original constellations that was devised by the Ancient Greco-Egyptian astronomer Ptolemy who lived between 90 A.D. and 168 A.D.

There are 10 stars that make up the main constellation. The hipparcos satellite scanned and detailed 2128 stars. There are 80 stars that can be seen with the naked eye in the constellation on a very clear night sky.

Leo is a member constellation of the Zodiac grouping, a group of 12 star signs that astrologers use to predict someones future based on their date of birth and which constellation appeared when the Sun set. The Zodiac year may be divided up equally between the twelve signs but when they appear in the night sky no longer conforms to the Zodiac calendar. Leo is an equatorial constellation that can be seen by countries nearest the Equator.

There are 28 Extrasolar Planets (Exoplanets) in this constellation that are detailed on this site. There is a dedicated page for exoplanets in Leo. The current largest star so far identified in the constellation of Leo is CW Leonis.

There are 5 deep space objects that were identified by Charles Messier in this constellation. There are no non-Messier deep space objects in this constellation that are covered at present on this site.

The image at the top right of this page was generated using Night Vision, a free to use and download application by Brian Simspon.

Distance to Leo

You can't just go to one location and arrive at the constellation because the constellation is made up of stars at different locations and different distances. The nearest main star in the constellation is at a distance of 35.88 light years and the furthest main star is a distance of 1,269.12 light years. The average distance to the main stars is 246.00 light years.

Leo Star Facts

The caveat of these stars are that they are catalogued on this site. If you know of a star that is nearer or further then do let me know in the comments and I'll add it to the site. The stars mentioned are from the Hipparcos catalogue or have been added because of their special status.

XZ Leonis, Leo's Furthest Star

The furthest star that is located in the constellation is XZ Leonis and it is 108721.1 light years away from the Sun. The furthest figure is derived from either the 1997 or 2007 Hipparcos star catalogue parallax figure and it has been known to produce distances that are wrong.

35 Leonis, Leo's Dimmest Visible Star

The dimmest star that can be seen in Leo with the naked eye is 35 Leonis. The dim star has an apparent magnitude of 5.95. The dimmest star that a person is able to see with their naked eye is 6.0 magnitude based on the table in the reference. Ref: University of Michigan.

Algieba

Algieba is a double star system and also has a planet in orbit. This may sound a little like Tatooine in Star Wars where the desert planet has two stars. The bad news with Algieba is that the planet is a giant gas planet so there's no chance of living on or finding intelligent alien life there. Algieba is not the only star in the constellation to have planets in orbit, there is also Rasalas with a planet, still sadly inhospitable.

Caffau's Star

Caffau's Star is named after Elisabetta Caffau who led a study into the star. Caffau's Star is an enigma, it shouldn't exist. Analysis of the chemicals in the star, the star is a metal poor star, consisting of mainly hydrogen and helium and not much other metals. It has been estimated that the star is about 13 Billion Years old which if true, it would mean it is one of the Oldest and Earliest Stars in the galaxy.

CW Leonis, Largest star in Leo

CW Leonis is one of the largest stars in the night sky. It is a carbon star having gone through its hydrogen and helium stages and now moving into the death stage. As the star is one of the largest and a carbon star, it makes for some interesting study.

Regulus, Brightest Star in Leo

The brightest star in the constellation is Regulus, also refered to as Alpha Leonis. The star is multiple star system with four stars including the large blue star that makes up this system. It is one of a group of major stars known that is oval (egg) in shape. The others being Vega and Achernar. The fact that Regulus has orbiting stars could well explain its shape but Vega is a solo star.

Wolf 359, Local Star

In astronomical speak, the constellation contains one of the closest stars to our own, Wolf 359. It is a small red dwarf star that is located to the bottom left of Regulus, near the border with the Sextants constellation. It lies a mere 7.86 light years away but unfortunately we don't have the space ships to travel that distance yet. Nearer stars include Proxima Centauri and Barnard's Star.

Zosma, Third Brightest in Leo

Zosma despite it having Delta designation, Zosma is brighter than the star with the Gamma designation, Algieba. Zosma is a fast moving star and it is believed that in about 518,000 years it will brighten up considerably. Zosma is a dying star and will not last as long as other stars.

How to Find and View Leo in the Night Sky

Northern Hemisphere

Leo can be viewed at the beginning of the year from about 10pm on NE-E horizon. If you wait a month, it can be viewed at about 8pm, still on the easterly horizon but as the night carries on. March and April present a better chance to see the constellation when it will be higher in the sky at about 9pm in a easterly direction. May is a good time to see it before it starts getting too bright to see it without staying up even later. At about 10pm, it will be high in the sky to see. Failing that, you will need to wait until December to see it again but only in the really early hours.

Southern Hemisphere

The best time to see Leo at about 9pm is in March when it can be viewed on the horizon. As the night goes on, it will rise in the sky but not as much as it does in the northern hemisphere. April, May and June all allow for you to see the constellation at about 9pm.

Leo Mythology

Leo represents one of the labours of Hercules. He was ordered to do it as punishment for killing his wife. The lion was terrorising the area near Nemea. He killed the beast by strangling it or choking it to death. The skin was thickest of all known animals which meant all weapons were useless against it. Hercules managed to skin the Lion using tools provided to him by Athena.

Meteor Showers Radiating from Leo

There are 33 Meteor Showers that occur during the year within this constellation based on information gathered from Adam Mickiewicz University (Poland). The list below are major ones and which I have a date period for.

NameActivityPeak ActivityClosest Star
Alpha Leonids13-Jan - 13-Feb24/31 JanRegulus
Southern delta Leonids23rd FebruaryZosma
Delta LeonidsFeb 15 - Mar 10 Feb 25Zosma
Sigma Leonids9-Feb - 13 MarFeb 25 - 26Sigma Leonis
Northern delta Leonids27th FebruaryZosma
Rho LeonidsFeb 13 - Mar 13Mar 1 - 4Rho Leonis
Northern alpha Leonids9th MarchRegulus
Beta LeonidsFeb 14 - Apr 25Mar 19/21Denebola
May Delta Leonids15th MayZosma
Daytime Gamma Leonids22th AugustAlgieba
Gamma LeonidsAug 14-Sept 12Aug. 25/26Algieba
Daytime Chi Leonids27th AugustChi Leonis
LeonidsNovember 13-20Nov. 17/18Adhafera


List of Main Stars in Leo

The following list contains the stars that make up the constellation. For a larger list of stars in the entire constellation area, please visit the For a list of named stars, that is stars that don't start HD or HIP, please visit Leo Star List page.

NameBayerDistance (Lt.Yr.)Right AscensionDeclinationSpectral TypeColour
RegulusAlpha Leonis79.3010h 08m 22.46+11d 58` 01.9B7VBlue/White
DenebolaBeta Leonis35.8811h 49m 03.88+14d 34` 20.4A3VvarWhite
AlgiebaGamma Leonis130.1010h 19m 58.16+19d 50` 30.7K0IIIOrange
ZosmaDelta Leonis58.4311h 14m 06.41+20d 31` 26.5A4VWhite
Ras Elased AustralisEpsilon Leonis246.7209h 45m 51.10+23d 46` 27.4G0IIYellow
AdhaferaZeta Leonis274.0910h 16m 41.40+23d 25` 02.4F0IIIYellow/White
Al JabhahEta Leonis1269.1210h 07m 19.95+16d 45` 45.6A0IbWhite
ChertanTheta Leonis165.0611h 14m 14.44+15d 25` 47.1A2VWhite
Iota LeonisIota Leonis77.2211h 23m 55.37+10d 31` 46.9F2IV SBYellow/White
RasalasMu Leonis124.1109h 52m 45.96+26d 00` 25.5K0IIIOrange

Leo Facts


NameLeo
AbbreviationLeo
Is a Zodiac Sign Yes
Brightest StarRegulus
Area946.964 sq. deg.
Percentage of Night Sky2.3%
Size Position12th
Hemisphere Equatorial
Site Exoplanet Count28
Meteor Shower Count33
Nearest StarWolf 359
Nearest Star with Exoplanet(s)HIP 57087
Largest StarCW Leonis
Brightest StarRegulus
Dimmest Star35 Leonis
Furthest StarXZ Leonis
Bright Star Count80
Hipparcos Star Count2128
Main Star Count10
Messier Deep Space Object Count5
Bordering / Neighbouring / Surrounding ConstellationsLeo Minor
Cancer
Hydra
Sextans
Crater
Virgo
Coma Berenices
Ursa Major

*Note: The number of Non-Messier Deep Space Object Count relates to how many are covered on this site not how many there are.


List of Deep Space Objects (Galaxies, Nebulas, Supernovas, etc) in Leo


NameTypeDistanceDeclinationRight Ascension
IC2810Galaxy450 Million Ly+14 40 35.9811 25 45m 055
Messier 105 (NGC3379)Elliptical Galaxy30,400-33,600 kly+12:3510h 47m 8
Messier 65 (NGC3623)Spiral Galaxy41,000-42,000 kly+13:0511h 18m 9
Messier 66 (NGC3627)Spiral Galaxy31,000-41,000 kly+12:5911h 20m 2
Messier 95 (NGC3351)Spiral Galaxy31,200-34,000 kly+11:4210h 44m 0
Messier 96 (NGC3368)Elliptical Galaxy28,000-34,000 kly+11:4910h 46m 8
NGC 3384Galaxy in a Group of Galaxies+12 37 45.4810 48 16m 897
NGC 3389Galaxy in a Group of Galaxies+12 31 59.64993405010 48 27m 9085192355
NGC 3455Spiral Galaxy65 Million Ly17:17:22.2810h 54h 29m 72
NGC 3810Spiral Galaxy50 Million Ly11:28:02.5011h 40h 58m 33


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