Leo the Lion - Stars, Symbols and Myths
Leo the Lion
The constellation Leo lies between Cancer and Virgo in the sky. It’s a constellation of the zodiac.
Twelve constellations comprise the zodiac: Aries, Taurus, Gemini, Leo, Cancer, Virgo, Libra, Scorpio, Capricorn, Sagittarius, Aquarius, and Pisces. All these constellations follow the ecliptic, an imaginary line that the sun follows throughout the year.
If you’re looking at the sky, Leo is 9° east of Cancer and 12° northeast of the constellation Hydra.
The constellations often have a number of stories and legends attached to them. Leo is no different.
Curiously, Leo is one of the most ancient of recognized constellations. Ancient peoples associated it with the sun. From the ancient Babylonians to the Egyptians, Leo has always been one of the signs of the zodiac.
The History of the Constellation
As long as four thousand years ago, the Babylonians measured the longitude of the brightest star in Leo: Regulus.
Then, two thousand years later, Hipparchus did the same. His observations of Regulus coupled with the star Spica helped his endeavor to discover the orbital path of the equinoxes relative to earth, called precession of the equinoxes.
Copernicus named the star Regulus. Its name stands for little king. It had other names as well: King, The Mighty, and The Hero among others.
According to the early Persians, Regulus was one of four guardian stars. The others were Fomalhaut, Aldebaran and Antares.
In mythological history, Hercules killed the Nemean Lion named Leo. Interestingly, Leo Minor and the Sextans—constellations adjacent to Leo —have no known mythological connections.
Leo in the Night Sky
When you look at this constellation, you’ll notice it has a hook pattern that looks like a backward question mark, called the sickle. This formation of stars makes up Leo’s head. The star Regulus sits at the bottom, with five other main stars – η Leonis, Algeiba, Aldhafera, Rasalas and Asad Australis –making up the rest of the sickle. With the exception of η Leonis, these are the Latin names of the stars. See the chart for the Greek names, which are more commonly used in the scientific community.
Leo is near the constellation Ursa Major, located just south of it in the sky.
Leo’s body extends out from the sickle. The star Denebola makes up the back, with two other stars—Zosma and Chort—forming a triangle.
The Stars in the Constellation Leo
Star - Greek Name
Magnitude (brightness, "0" = brightest)
2.3, 3.5 (double star)
5-11, variable star
Can you locate the constellation Leo in the sky?
This star forms the bottom part of the sickle. This star is interesting in that it lies on the ecliptic. Thus, once yearly, the sun eclipses Regulus, on August 23.
This star is 71 light years away and is getting farther away, at a rate of 1.5 miles per second. It’s about 130 times brighter than the Sun and shines as a white to blue-white star. Its magnitude is 1.3, meaning it’s pretty bright. Despite the high magnitude, it’s still only the 19th brightest out of the 20 brightest stars in the sky.
You can see Regulus in the sky about eight months out of the year if you live in the northern hemisphere. Starting January 1st, you can see it in the northeastern sky at about 9 pm. It gets to its highest point in the sky in early spring. By April 8th, it’s high in the northern sky at 9 pm.
Regulus also has a companion star, but it’s a lot dimmer, at the 8th magnitude (level of brightness).
Making up the back part of Leo, the star Denebola is most prominent, making up the tail. It’s almost as bright as Regulus, though not quite. It has a magnitude of 2. Ancient peoples calculated its magnitude in the “1” range, but otherwise, its brightness has not changed much over the millennia.
Looking at the sky, Denebola is 25° east of Regulus. It’s 16 times brighter than the sun, 39 light years away, and moving away from us at 1 mile per second.
Denebola is also named β Leonis. Together with δ Leonis and θ Leonis, they make up a triangle shape at the back of Leo, as mentioned above.
Stars in Leo
λ Leonis is a double star, just southwest of the sickle. It’s actually approaching us at 24 miles per second.
It’s a beautiful double star and one that it does well to observe it at moonlight or just before dark. You’ll be able to see the brilliant yellow-orange and green colors of the two stars. The yellow-orange star is brighter than the other with a magnitude of 2.2 and 3.5 respectively.
It’s difficult to see these double stars with the naked eye, but a small telescope should be sufficient to see them. Their revolution isn’t that fast. It takes them just under 100 years to complete one revolution.
Another interesting star is R Leonis. It lies southwest of Regulus, just under the ecliptic. It’s what’s known as a variable star. Its brightness changes, ranging from a magnitude of 5 (at its brightest) to 11 (pretty dim) every 313 days. When R Leonis is at magnitude 5, it looks red and is visible to the naked eye.
Galaxies and Leonids Meteor Showers
Just west of Leo’s “body” lie five galaxies. Most notable are M65 and M66. They are 29 million light-years away. You can’t see them with the naked eye, but with binoculars, you can barely make them out.
In November, you can see the Leonids meteor shower. These meteors emanate from Leo’s head and culminate every November 14th or 15th.
Indeed, this is an interesting constellation, with an ancient history and many interesting objects in the sky.
Field Book of the Skies. Olcott, William. Van Rees Press: New York. 1974.
Guide to Stars and Planets. Moore, Sir Patrick. Firefly Books: New York. 2005
Seasonal Star Charts. Hubbard Scientific Company, 1972.
The Handy Space Answer Book. Dupuis, Diane and Phillis Engelbert. Visible Ink Press: Canton, MI. 1998.
Questions & Answers
© 2012 Cynthia Calhoun