Leo Constellation: The Lion Among the Stars

Leo the Lion is one of the most distinctive constellations of the spring sky. Its bright stars form a pattern that genuinely resembles a crouching lion, making it one of the few constellations whose shape matches its name. As a zodiac constellation, the Sun passes through Leo each August. Find it overhead tonight using StarGlobe.

How to Find Leo in the Night Sky

The easiest way to locate Leo is to use the Big Dipper in Ursa Major as a guide. The two stars on the back of the Dipper's bowl, Megrez and Phecda, form a pointer line. Extend that line southward, and it leads to Regulus, the brightest star in Leo.

Alternatively, look for a distinctive backward question mark or sickle shape in the south during spring evenings. This asterism, called the Sickle of Leo, forms the lion's head and mane. Regulus sits at the base of the Sickle, marking the lion's heart. A triangle of stars to the east forms the lion's hindquarters and tail, with Denebola marking the tail tip.

Leo is relatively easy to identify because its stars are bright and its shape is distinctive. Even from suburban skies, the Sickle stands out clearly among the dimmer surrounding stars.

The Stars of Leo

Regulus, at magnitude 1.4, is the 21st brightest star in the sky. It is a blue-white main-sequence star about 79 light-years from Earth, spinning so rapidly that it is significantly flattened at its poles. Regulus sits almost exactly on the ecliptic, meaning the Moon and planets frequently pass very close to it or even occult it.

Denebola, at the lion's tail, shines at magnitude 2.1. It is a white main-sequence star about 36 light-years away that has an excess of infrared radiation, suggesting a disk of dust and possibly a young planetary system around it.

Algieba, in the Sickle, is a beautiful double star for telescope users. A small telescope splits it into two golden-orange components orbiting each other. This pair is one of the finest double stars in the spring sky. Zosma and Chertan complete the triangle of the lion's haunches.

Deep Sky Objects in Leo

Leo is home to several bright galaxies, making it a favorite hunting ground for galaxy observers in spring. The Leo Triplet, consisting of M65, M66, and NGC 3628, is a group of interacting galaxies about 35 million light-years away. All three are visible in a single telescope field of view and make a stunning target.

M95 and M96 form another galaxy pair in Leo, both spiral galaxies at a distance of roughly 33 million light-years. Nearby M105 is an elliptical galaxy. Together, these galaxies are part of the Leo I Group, one of the nearest galaxy groups beyond our own Local Group.

For those with larger telescopes, Leo contains numerous fainter galaxies scattered throughout its boundaries, taking advantage of the fact that the constellation points away from the obscuring plane of the Milky Way and out into deep intergalactic space.

Mythology and Cultural Heritage

In Greek mythology, Leo represents the Nemean Lion, a fearsome beast with an impenetrable hide that terrorized the region of Nemea. Killing the lion was the first of the twelve labors of Heracles (Hercules). Finding that his arrows and sword were useless against its hide, Heracles strangled the lion and wore its skin as armor thereafter. Zeus placed the lion among the stars to honor the battle.

The Egyptians associated Leo with the annual flooding of the Nile, which historically occurred when the Sun was in Leo during midsummer. Lions were symbols of royal power in many ancient cultures, and the bright star Regulus takes its name from the Latin word for "little king."

In Babylonian astronomy, the constellation was also recognized as a lion, making it one of the oldest continuously identified star patterns. Hindu astronomy associates the constellation with a couch or resting place.

The Leonid Meteor Shower

Each November, the Leonid meteor shower appears to radiate from a point within Leo. The Leonids are caused by debris from Comet Tempel-Tuttle, which orbits the Sun every 33 years. In most years, the shower produces a modest 10 to 15 meteors per hour, but roughly every 33 years, when Earth passes through denser debris streams, the Leonids can produce spectacular meteor storms with thousands of meteors per hour. The great Leonid storms of 1833, 1866, and 1966 are among the most dramatic astronomical events in recorded history.

Best Time to Observe

Leo is best observed during spring evenings from both hemispheres. The constellation rises in the east during February evenings, reaches its highest point in the south (for northern observers) in April, and sinks into the western twilight by July. From late March through early May, Leo dominates the evening sky and is well-placed for observing its galaxies.

As a zodiac constellation, Leo lies along the ecliptic, so the Moon and bright planets regularly pass through it, creating eye-catching conjunctions with Regulus.

Neighboring Constellations

Virgo lies to the east of Leo, with Spica marking the next bright star along the ecliptic. Cancer sits to the west, and Ursa Major sprawls above it to the north. Leo Minor, a faint constellation, occupies the space between Leo and the Great Bear. To the south lies the dim constellation Sextans and the cup-shaped Crater.

Spring is galaxy season, and the arc from Leo through Virgo to Coma Berenices contains the densest concentration of bright galaxies in the sky. Open StarGlobe to trace this path and explore the spring sky from your location.

Quick Facts

Leo covers 947 square degrees, making it the 12th-largest constellation. It contains five Messier objects, all galaxies. Regulus shines at magnitude 1.4, and the constellation includes several stars brighter than magnitude 3.0. Leo's right ascension ranges from about 9h 21m to 11h 58m, and its declination spans from about -6 to +33 degrees.