LEO (pronounced LEE-oh)

Chart showing Leo and Leo Minor

Leo, the Lion is one of the few constellations that looks like the figure it is supposed to represent - in this case, a crouching lion, though this is upside-down to us in the southern hemisphere. The lion's head is outlined by a sickle shape of six stars with the body stretching out to the left. The tail is marked by β Leonis.

This lion is the one slain by Hercules as the first of his twelve labours. Ptolemy assigned 27 stars to the ancient constellation. Every year around November 17th, the Leonid meteors appear to come from a point near γ Leonis. Usually the numbers are low, but on occasions spectacular storms are recorded. These usually happen around each 33 years.

Leo Minor was introduced by Johannes Hevelius, the Polish astronomer, in the late 17th Century. There is little of interest, and the labelling of its stars is very fragmentary, testimony to the cavalier treatment by successive generations of celestial cartographers.

To find Leo look towards the north to find bright Regulus and the backward "sickle" shape below. Leo Minor is below.

Chart showing Leo and Leo Minor as seen to the north at about 10 pm on April 15 or 8 pm on May 15.

Leo and Leo Minor.

Constellation Hydra Constellation Sextans Constellation Crater Constellation Virgo Coma Berenice Canes Venatici Ursa Major Constellation Lynx Constellation Gemini Constellation Cancer

Details of some of the objects shown in the chart.

α Leonis (Regulus) is a magnitude 1.4 blue-white star 85 light years away. It has an orange-red companion magnitude 7.6, visible in binoculars or small telescopes. This companion is also binary but its faint companion is difficult to see.

β Leo (Denebola, lion's tail) is a magnitude 2.1 white stars 42 light years away.

γ Leo (Algeiba, lion's mane) at 100 light years away, is a beautiful pair of stars easily seen in small telescopes, with a period of about 600 years. The stars are golden-yellow giants of magnitudes 2.3 and 3.5. In binoculars, an unrelated 5th magnitude yellow star is visible nearby.

δ Leo (Zosma) is a magnitude 2.6 blue-white star 52 light years away.

ζ Leo (Adhafera) is a magnitude 3.4 white star 120 light years away. Binoculars show an unrelated orange background star nearby of magnitude 5.8. A 3rd star of magnitude 6.0 and also unrelated can be seen father off in binoculars, making this an optical triple.

ι Leo is a close double star with components revolving round each other every 192 years. The magnitude 4.1 and 7.0 yellow-white stars lie 78 light years away.

M65 (NGC 3623) is an edgewise spiral with a bright central region. It has a long dark absorption lane near the eastern edge.

M66 (NGC 3627) is a spiral galaxy shining at magnitude 8. It can be detected in large binoculars and small telescopes, although larger instruments are need to see its spindle shape.

M95 (NGC3351) is photographically a beautiful spiral galaxy, but it appears as a 10th magnitude hazy spot in amateur telescopes. It forms a group of galaxies with M96, M105, and NGC 3384 at about 33,000,000 light years away.

M96 (NGC 3368) is a fine spiral galaxy with a bright inner region, shining at 9th magnitude.

M105 (NGC3379) is a round bright elliptical galaxy forming a triangle with M95 and M96. This galaxy is used as a photometric standard for extended objects.


Leo lies on and to the north of the equator. Regulus is to the north at 10 pm at the beginning of April and at 8 pm and the end of the month. The constellation is visible early evening up to late July, when Regulus will set soon after 6 pm.

During 2009 the planet Saturn will be about 16° from Regulus and moving near the stars σ Leo, mag 4.0 and χ Leo, mag 4.6.