Leo is one of the easiest constellations to recognize and has been pictured as a lion by many different cultures since ancient times, including by the Indians, Persians, and Greeks. It is the 12th largest constellation in the night sky, and rather hard to miss with a ‘sickle of stars’ forming the front part of its distinctive sphinx-like figure.
Leo contains the 22nd brightest star in the entire night sky, Regulus, a blue-white star located 77 light years from Earth, which also forms part of a distinctive asterism of stars called the Spring Triangle, together with Arcturus in Boötes, and Spica in Virgo.
Mythology of the constellation Leo
The constellation of Leo represents the Nemean Lion from Greek mythology, although the constellation’s association with a lion dates back to at least 4000 BC Mesopotamia.
The 12 Labours of Hercules were tasks carried out by Heracles to atone for the Hera-induced madness that caused him to kill his wife and children. The first of his labors was to slay a fearsome lion that had been preying on people around the hills of Nemea in ancient Greece. The Nemean lion’s skin was impenetrable, and so after his arrows proved ineffectual, Heracles trapped the man-eating lion in its cave and during a fierce struggle choked it to death. Hercules then used one of its claws to skin the animal and thereafter wore its pelt as an impenetrable mantle to make him even more fearsome. To commemorate his son Hercule’s victory, Zeus placed the lion in the sky as the constellation Leo.
The shape of Leo resembles a Lion
Leo occupies an area of 947 square degrees, making it the third largest of the 12 zodiacal constellations, after Virgo and Aquarius. The constellation is easily recognized as the majestic lion it depicts, with its asterism of six stars a striking formation in its own right. This backward question mark is called “the Sickle” and represents the lion’s mane and shoulders.
Use the Big Dipper to find Leo constellation
Leo is a northern sky constellation visible to observers between latitudes +90 and -65 degrees. In order to locate Leo, first find the Big Dipper asterism and then use its two pointer stars to trace a line across to Regulus, the brightest star in the constellation Leo.
The constellation can be found in the sky between Cancer to the west and Virgo to the east. Other nearby star constellations include Hydra and Leo Minor, directly above Leo, as well as Coma Berenices, which is formed from the stars of the lion’s “tail.”
Leo is best seen in April and May
Leo is a winter constellation that is visible in the northern hemisphere from January to June, but rises to prominence around the time of the spring equinox in March. In the southern hemisphere, Leo can be seen during summer and autumn.
Leo contains the 21st brightest star Regulus
The constellation of Leo contains four stars of first or second magnitude, making it appear particularly prominent in the night sky. Leo also contains more than a dozen stars with known planets between them, although none of the stars in the Leo constellation have planets in their habitable zones.
– Regulus (Alpha Leonis) is a multiple system located about 77 light years away with an apparent visual magnitude of 1.35, making it the most luminous star in Leo, and the 21st brightest star in the entire night sky. In actual fact, Regulus consists of two binary systems orbiting each other, with the primary system, Regulus A, a blue-white main-sequence star (B7V) orbiting a suspected white dwarf 0.35 AU away once every 40 days or so.
The other system consists of Regulus B, an orange dwarf (K1-2 V), and Regulus C, a red dwarf (M5 V) situated 4,200 AU away from the main pair, separated by 100 AU, and with an orbital period of 2,000 years. Regulus means “little king” in Latin and is one of the stars from which longitude is reckoned, as it lies almost exactly on the ecliptic and is visible for eight months of the year.
– Algieba (Gamma Leonis), the constellation’s second brightest star, is a binary system of magnitude 2.28, situated 130 light years from our star system. Its primary star is an orange giant (K1-IIIbCN-0.5) that is 23 times bigger than the Sun, and at least 180 times brighter, while its dimmer companion, a yellow giant (G7IIICN-I) is 10 times bigger than the Sun and about 50 times as bright. The pair orbit each other once every 500 or so years, with a planet having been discovered orbiting the primary component. Algieba derives from the Arabic for ‘the forehead,’ although the star actually marks the lion’s mane.
– Denebola (Beta Leonis), the third most luminous star in Leo, is a blue main sequence dwarf (A3 Va) found 36 light distant that shines with a visual magnitude of 2.14. It is around 200 million years old, and is 1.75 times the size of the Sun, and around 12 times brighter. The name Denebola comes from the Arabic phrase meaning ‘Tail of the Lion.’
Other stars of interest in Leo include Zosma (“Hip of the Lion”), Ras Elased Australis (“Head of the Lion”), Chertan (“The Rib”), Subra (“Head of the Lion”), and Al Minliar al Asad (“Muzzle of the Lion”). The constellation also includes Wolf 359, a red dwarf star that at only 7.78 light years distant is one of the closest stars to Earth. It is about as small as an actual burning star can get, too, being just 8% of the mass of our Sun, and about the same size as Jupiter.
Notable objects include many bright galaxies
There are a number of impressive deep sky objects in Leo, including 5 Messier objects. These include the spiral galaxies M65, M66, M95, M96, and the elliptical galaxy M105:
– Messier 65 (M65, NGC 3623) is an intermediate spiral galaxy, and at a distance of about 35 million light years, has an apparent visual magnitude of 10.25. This galaxy contains very little gas and dust, meaning that star formation no longer takes place in significant numbers, and thus the vast majority of its stars are very old.
– Messier 66 (M66, NGC 3627) is another intermediate spiral galaxy that is 36 million light-years distant, and spread across 95 thousand light-years of space. It has an apparent visual magnitude of 8.9, and has had four recorded supernovae.
– Messier 95 (M95, NGC 3351) is a barred spiral galaxy that is about 38 million light-years distant, and with an apparent visual magnitude of 11.4. M95 is also a member of the M96 Group of galaxies that includes M96 itself, M105, and at least nine other galaxies of various types. M95 is notable for the 2,000 light-year-diameter ring-shaped star-burst region around its core, as well as the fact that a supernova was detected in the galaxy in March of 2012.
Leo contains 3rd largest object in the Universe
Leo also contains Huge-LQG, the largest quasar group yet found and the third biggest structure in the whole universe overall. This enormous expanse consists of 73 quasars spread across 4 billion light-years of space, as compared to our entire Milky Way, which is just 100,000 light-years across. The only structures bigger are the Hercules-Corona Borealis Great Wall, which is 10 billion light-years wide, and the Giant GRB Ring, which is 5.6 billion light-years across.
Leonids meteor shower seen in November
The Leo star constellation is home to the following meteor showers, with their peak dates noted in the brackets – Delta Leonid (end of Feb), Sigma Leonid (April 17), Leonids (Nov 17th), and Leo Minorids (Dec 14).
The Leonids is associated with the comet Tempel-Tuttle and is one of the most spectacular and biggest meteor showers of the year. It is visible from November 13th to 21st, and peaks on the 17th when 20 or more meteors can be seen per hour. Once every 33 years, however, a periodic meteor storm takes place in which thousands of meteors can be seen every hour, with the next expected to occur in 2032. The biggest one to date occurred in 1833, with estimates placing the count at between 100,000 and 240,000 per hour for the 9 hours it rained down. That’s right, up to 4,000 meteors per minute, or 67 per second. In a famous piece of artwork depicting The Great Leonids Meteor Storm, you can see that, in a time when there were no indoor and outdoor lights, the scene is lit almost as brightly as daytime.
Leo astrological sign and association
- Date of Birth: July 23 to August 22
- Sign Ruler: Sun
- Element: Fire
- Birth Stone: Peridot, Ruby
- Metal: Gold
- Color: Red, Gold, Yellow
- Characteristics: Proud, Charitable, Reflective, Loyal, Enthusiastic
- Compatibility: Aries, Sagittarius
Egypt associated Leo with the flooding of the Nile
Although it is not entirely clear how the constellation Leo became known to the ancient Egyptians, one enchanting piece of star lore goes as follows. The ancient Egyptians worshiped Leo because they knew the Sun entered the constellation during the Flooding of the Nile, which brought significant amounts of water and fertile soil onto the land. Food security in Egypt depended on this annual natural cycle, a circumstance that also coincided with the arrival of desert lions at the river. Although the lions moved toward the river to avoid the heat and lack of water in the desert at that time, a connection was made by the Egyptians, who honored the lion with festivals, and even today many statues of lions can be found along the course of the Nile River, proof of the reverence with which the ancient Egyptians regarded the desert lions.
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