All About The Leo Constellation

Few constellations strike such a clear and present visage as Leo, and rarely do constellations so well mimic the general shape of their namesake—but Leo succeeds in portraying the outline of a crouching lion so well that human civilizations have been describing it in the same way for thousands of years.

True to form, like a ‘mighty roar’ in the night sky, Leo is filled with incredibly bright stars that distinctly mark its boundaries practically demanding an observer’s attention. More than that, Leo is also home to one of the most important and prolific meteor showers in the night sky: the Leonids.

These showers have been documented for hundreds of years across the world, but the storm of 1833 marked an incredible shift in the study of meteor showers, and furthered humanity’s obsession with them. While it is typically humans who leave their mark on the night sky through the stories and tales ascribed to constellations, rarely are observable events like Leo and its meteor shower able to leave a greater mark on us.

Leo Constellation Mythology

Leo is one of the original forty-eight constellations documented by the Greek-Egyptian astronomer Ptolomy in the 2nd century, and it continues to be one of the most recognizable of the modern eighty-eight. In Greek mythology, Leo represents the Nemean lion—a beast with fur impenetrable to all but the most powerful weapons.

Most notably portrayed in the legend of Hercules, the defeat of the Nemean lion is the first of his Twelve Labors. Given the lion's impressive defense against weapons, Hercules is forced to fight the lion in hand-to-hand combat, eventually strangling it to death. Further, in more popular versions of the myth, he uses the lion’s own claws to skin it, and goes on to wear the pelt as protective armor. In recognition of this great feat, Zeus placed the lion in the sky.

With that in mind, the Latin name Leo would eventually come down to us from Roman retellings of the myth; ‘Leo’ being their word for ‘Lion’, and also the root of the modern English word.

Despite this being the most familiar origin story of the constellation Leo, its prevalence in human mythology extends beyond the ancient Mediterranean and much further back in time. The ancient Persians referred to it as Ser or Shir, the Turkic people of central Asia as Artan, the ancient Syrians as Aryo, the Hebrews called it Arye, and as far east as India it was known as Simha.

Interestingly, all of these terms translate to ‘lion’ from their native tongues. It is even believed that the civilizations of Mesopotamia, a rival to Egypt as the most ancient on Earth, charted a constellation similar to Leo as far back as 4000 B.C.E. Additionally, the ancient Babylonians, a successor state to those of Mesopotamia, associated the constellation (known to them as ‘UR.GU.LA’, the Great Lion) with their own warrior of legend, the king Gilgamesh. In the Epic of Gilgamesh, the titular character sets out on a quest to defeat the monster Humbaba, a lion like creator.

By Till Credner - Own work: AlltheSky.com

Behind the Roar

Part of human fascination with Leo constellation is its distinct and luminous stars, the brightest of which is called Regulus. Regulus may appear as a single point in the sky, but it is actually a grouping of several stars which orbit each other. Its central star, Regulus A, is three times as wide as the sun, nearly two-hundred and eighty-eight times as luminous, and spins at such a rapid rate that its shape is oblate.

The name Regulus, as English has taken the root in the form of ‘regal’ is derived from the Latin word for ‘prince’ or ‘little king’, and continues a long history of royal designations. That being said, the ancient Persians in 3000 B.C.E. knew it as one of the four ‘royal stars’, the guardians of the sky, while in Arabia it was referred to as Malikiyy or, the ‘kingly one’. Further still, in China the star has been called Xuanyuan, one of the documented names of the ‘Yellow Emperor’, a mytho-historical figure who is said to have been an early founder of the Chinese state.

Regulus is often grouped with six other stars of Leo’s mane and shoulders into the ‘Sickle’ asterism, the second most recognizable asterism in the night sky after the ‘Big Dipper’. Some other stars of the asterism are Algieba, from the Arabic word Al-Jabhah meaning ‘the forehead’ (despite being located in the mane). This star is actually part of a binary pair, consisting of two red-giant stars who have swollen immensely inside after switching from hydrogen to helium fusion. Other stars of the ‘Sickle’ are the giant star Adhafera (from the Arabic word aḍ-ḍafīrah meaning the ‘braid/curl’), and the second brightest star of the constellation Denebola (from the Arabic phrase ðanab al-asad meaning ‘tail of the lion’).

In addition to stars, several deep-space objects of note can also be found within Leo Constellation. Bright galaxies such as those of the ‘Leo Triplet’: M65, M66, and NGC 3628. The last of these is known as the ‘Hamburger’ galaxy, which goes to show the wide spectrum of names objects in space can come to have.

The ‘Leo Ring’ is another feature of the constellation. It is a 650 kilo-light-year sized gas cloud of primarily hydrogen and helium that orbits two galaxies of the ‘Leo Group’ of galaxies (not to be confused with the ‘Leo Triplet’, there are a lot of galaxies behind this constellation). The ‘Leo Ring’ is thought to be the remains of a collision between two galaxies, resulting in the ejection of a galaxy’s worth of gas into space.

A Star Shower

Beyond all these features, Leo constellation has managed to capture human imagination through its regular meteor showers, known as the Leonids. Caused yearly by the comet Tempel–Tuttle, the Leonids are famous for the absolutely massive meteor storm that results from them roughly every thirty-three years. The most famous of these occurred in 1833, primarily over North America, and was so massive it is estimated that over one-hundred-thousand meteors fell an hour. The event was viewed across the world, and commented on by such figures as Abraham Lincoln, Frederick Douglas, and Harriet Tubman (who referred to it as, ‘the night the stars fell.’) Even Native American tribes are said to have commented on, and documented the incredible event.

Further, the meteor shower coincided, and in some part inspired, the growth of modern astronomical studies—helping to launch a reinvigorated study of meteor showers and astronomical events. Meteor showers had previously been viewed as atmospheric events, but the meteor storm of 1833 helped scientists to examine comets and other such objects as potential origin points.

The Impact of Leo Constellation & Where to Find It

The amazing thing about Leo and the Leonids is the way they interact with us. While constellations can often be seen as static images in the night sky (in fact, stability is part of their appeal), Leo manages to act on our imagination in a way few constellations can—providing a yearly reminder of the wonder and beauty of cosmic phenomenon.

The constellation itself is located in the Northern celestial hemisphere, and is best visible in April; though the Leonids appear in March. All that being said, Leo constellation is a perfect starting point for amateur astronomers, who only look for the lion’s mane in the night sky to begin their watch.