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. The constellation gets its name as it 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.
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.
The brightest star in Leo is Regulus. 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. For a list of named stars, that is stars that don't start HD or HIP, please visit Leo Star List Page.
The number of stars that have been catalogued as part of the Hipparcos Star Catalogue from Leo is 2128. The number of stars that are of magnitude 6.0 or lower in the constellation is 80. The number of stars in the constellation that make up the outline is 10.
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 nearest star to Earth is Wolf 359 which is roughly about 7.86 Light Years from the Earth. The nearest star to the Earth with an exoplanet is HIP 57087 which is about 33.08 Light Years. The furthest star that can be located in the constellation is HIP 49204 which is located about 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.
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
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.
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.
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.
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.
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.
There are 33 Meteor Showers that occur during the year within this constellation based on information gathered from Adam Mickiewicz University (Poland). The ones listed as the ones I've been able to find a date range for. For others if you have the time, you can visit the AMU site, obtains the SL value then use IMO tables to calculate the date. A lot of the Meteor Showers are weak and you need to do a lot of stargazing to spot them.
|Name||Activity||Peak Activity||Closest Star|
|Alpha Leonids||13-Jan - 13-Feb||24/31 Jan||Regulus|
|Delta Leonids||Feb 15 - Mar 10||Feb 25||Zosma|
|Sigma Leonids||9-Feb - 13 Mar||Feb 25 - 26||Sigma Leonis|
|Rho Leonids||Feb 13 - Mar 13||Mar 1 - 4||Rho Leonis|
|Beta Leonids||Feb 14 - Apr 25||Mar 19/21||Denebola|
|Gamma Leonids||Aug 14-Sept 12||Aug. 25/26||Algieba|
|Leonids||November 13-20||Nov. 17/18||Adhafera|
|Is a Zodiac Sign||Yes|
|Largest Star||CW Leonis|
|Area||946.964 sq. deg.|
|Percentage of Night Sky||2.3%|
|Site Exoplanet Count||28|
|Meteor Shower Count||33|
|Nearest Star||Wolf 359|
|Nearest Star with Exoplanet(s)||HIP 57087|
|Dimmest Star||35 Leonis|
|Furthest Star||HIP 49204|
|Bright Star Count||80|
|Hipparcos Star Count||2128|
|Main Star Count||10|
|Messier Deep Space Object Count||5|
|*Non-Messier Deep Space Object Count||0|
|Bordering / Neighbouring / Surrounding Constellations||Leo Minor|
*Note: The number of Non-Messier Deep Space Object Count relates to how many are covered on this site not how many there are.
The map was generated using Night Vision, an awesome free application by Brian Simpson.
|Messier 105 (NGC3379)||Elliptical Galaxy||30,400-33,600 kly||+12:35||10h 47m 8|
|Messier 65 (NGC3623)||Spiral Galaxy||41,000-42,000 kly||+13:05||11h 18m 9|
|Messier 66 (NGC3627)||Spiral Galaxy||31,000-41,000 kly||+12:59||11h 20m 2|
|Messier 95 (NGC3351)||Spiral Galaxy||31,200-34,000 kly||+11:42||10h 44m 0|
|Messier 96 (NGC3368)||Elliptical Galaxy||28,000-34,000 kly||+11:49||10h 46m 8|
The Delta Leonids are one of a few meteor showers that are associated with the Leo, the Lion constellation. The major meteor shower for Leo is the Leonids which occur in November. This one is so called because the radiant point is near Zosma, also known as Delta Leonis star.
|Max Activity Date||25 Feb|
|Activity Period||Feb 15 - Mar 10|
|Zenith Hourly Rate||2|
The Leonids Meteor Shower radiate point east of Adhafera , just around about where the Lion`s Head is. It is a heavy Meteor Shower compared to other meteor showers such as Piscis Austrinids.
The comet associated with the Meteor Shower is a short term comet which orbits the Sun every 33 years. Some comets journey can take thousands of years to complete an orbit which is why Tempel-Tuttle is referred to as a short term one. When the comet comes close to The Sun, the meteor shower can be quite spectacular such as in 1833.
|Max Activity Date||17 Nov|
|Activity Period||November 13-20|
|Zenith Hourly Rate||100|
|Max Activity Date||25 Aug|
|Activity Period||Aug 14-Sept 12|
|Max Activity Date||24 Jan|
|Activity Period||13-Jan - 13-Feb|
|Associated Comet||2002 GM5?|
|Max Activity Date||25 Feb|
|Activity Period||9-Feb - 13 Mar|
|Max Activity Date||19 Mar|
|Activity Period||Feb 14 - Apr 25|
|Max Activity Date||01 Mar|
|Activity Period||Feb 13 - Mar 13|