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Leo Constellation: Facts About the Lion

Leo the Lion is one of the earliest recognized constellations. The Mesopotamians are known to have documented the "lion" constellation. The Persians called it Ser or Shir; the Turks, Artan; the Syrians, Aryo; the Jewish, Arye; the Indians, Simha. These are all translated as “lion."

Hunting the lion

Leo is a highly recognizable constellation, as it is one of the few constellations that resemble its namesake. It is fairly easy to find because the "pointer stars" of the Big Dipper point to Leo.

March does come in with a lion. The constellation becomes visible in the Northern Hemisphere around the spring equinox and is easily identifiable through May. Leo lies between Cancer to the west and Virgo to the east.

  • Right ascension: 11 hours
  • Declination: 15 degrees
  • Visible between latitudes 90 and minus 65 degrees
  • Best seen in April at 9 p.m.

This sky chart shows where the constellation Leo, the Lion and its trademark sickle appear in the eastern sky as viewed from the Northern Hemisphere during spring. This chart is where the constellation appears at 8 p.m. EDT as viewed from the U.S. East Coast. (Image credit: Starry Night Software)

The constellation can be found by looking for the head of the lion, or the "sickle," starting at the Regulus (Alpha Leonis) star. Regulus, Al Jabbah, and Algieba, together with the fainter stars ζ Leo (Adhafera), μ Leo (Ras Elased Borealis), and ε Leo (Ras Elased Australis), constitute the sickle.

The brightest star in the curve of the sickle is Al Geiba, which means "the lion's mane." In January 2001, a large object eight times the size of Jupiter was discovered orbiting Al Geiba. A triangle of stars forms the lion's haunches. The brightest star of this trio is Denebola, which means "tail of the lion."

There are a number of luminous galaxies within Leo, including the Leo triplet of M66, M65 and NGC 3628. The Leo Ring, a cloud of hydrogen and helium gas, orbits of two dwarf galaxies.

Triplet of bright galaxies in the constellation of Leo (The Lion), together with a multitude of fainter objects: distant background galaxies and much closer Milky Way stars. The image hints at the power of the VST and OmegaCAM for surveying the extragalactic Universe and for mapping the low brightness objects of the galactic halo. (Image credit: ESO/INAF-VST/OmegaCAM. Acknowledgement: OmegaCen/Astro-WISE/Kapteyn Institute)


In Greek mythology, Leo is the Nemean Lion, which terrorized the citizens and had a hide that could not punctured by iron, bronze or stone. Killing the lion was one of Hercules' 12 labors, which he had to perform as penance for killing his family. Having broken all of his weapons fighting the man-eating lion, Hercules finally strangled it to death and placed it in the heavens as one of his conquests.

Astrology is not a science, but Leo is one of the 13 constellations of the Zodiac. Leo is the fifth sign of the Zodiac and represents those born July 22 to August 22. It is considered a masculine, extroverted sign. 

Exoplanets in Leo

Recent exoplanet discoveries in the constellation Leo show a cornucopia of strange words, as well as at least one planet that is potentially habitable.

Back in 2008, astronomers found a planet orbiting a dying red giant star known as HD 102272. It is about 1,200 light-years away from Earth. Astronomers noted that the star was extremely bloated and said that its interactions with the planet would be an interesting topic for a follow-up.

Astronomers announced the discovery of a large planet called GJ 436b in 2010, but things kept getting weirder with more observation. In 2015, astronomers announced that GJ 436b, which is roughly 22 times as massive as Earth, had a huge gas cloud streaming away from it for millions of miles. Follow-up observations announced in 2017 revealed the planet's orbit is also bizarre, as it goes over the star's poles. That's very different from our own solar system, where the planets' orbits gather around the sun's equator.

In late 2017, scientists announced there is a potentially rocky exoplanet called K2-18b that may be orbiting in the habitable zone of its red dwarf star, meaning that liquid water could exist on its surface. The planet is about 2.2 times bigger than Earth. Observations suggest it may be a water world with an ice shell, or a rocky world with a thin atmosphere.

Additional reporting by Elizabeth Howell, contributor.


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Kim Ann Zimmermann is a contributor to and sister site Live Science, writing mainly evergreen reference articles that provide background on myriad scientific topics, like the constellations, astronauts, climate, culture and medicine. Her work can also be found at Business News Daily and KM World. She holds a bachelor’s degree in communications from Glassboro State College.