Leo

'Neath her hind feet as rushing on his prey, The lordly Lion greets the God of day.'
-Aratos

Description

Leo is an impressive and easy to recognize constellation, dominating the spring skies in the northern hemisphere and autumn skies in the southern hemisphere. Leo is the fifth zodiac constellation and the one most easily recognized: the crouching lion facing westward, with a distinctive head and mane marked by a sickle of stars which look like a backwards question mark. The brightest star is Regulus, which lies south of the pointer stars in the Big Dipper and to the northwest of Virgo. Leo's midnight culmination is around March 1.

The lion has been identified with the Sun since the earliest Mesopotamian civilizations. In the formative period of settled civilizations in Mesopotamia and Egypt, some five millennia ago, the Sun's passage at midday through this area of the sky coincided with the midsummer solstice. Leo was therefore the constellation of high summer, which is manifestly the realm of the Sun.

The Dendera zodiac , or planisphere is a large sandstone medallion that shows many ancient constellations and asterisms. It was discovered on a ceiling in 1799 by one of Napoleon's officers in the temple of Isis at Dendera, which is located on the Nile River about 60 km north of Luxor. This star map is believed to date from the time of Cleopatra in the first century BC and to depict sky figures that were known in Egypt at that time, both indigenous as well as those borrowed from Mesopotamia and Greece. The Dendera planisphere shows a lion in the part of the sky that we associate with Leo.

The gates of the Egyptian canals irrigating the Nile valley were often decorated with a lion's head.

This portion of the sky lies in the direction of the great Virgo Cluster of galaxies, the nearest large galaxy cluster to the Milky Way. The Virgo Cluster is centered about 50 million light years from Earth, about 700,000 times farther from us that are the bright stars of Leo.

Around 240 B.C., Leo was robbed of his splendid tail. The astronomer-priest under Ptolemy III chopped of the tail of Leo when they invented the new constellation Coma Berenices (Berenice's Hair).

Mythology

In Roman mythology, Leo is identified with the Nemean lion that Hercules was required to skin a huge lion whose pelt was impervious to stone of metal. Having wrestled it with his bare hands and choked it to death, he used the beast's own claws to skin it. He then took the pelt as a cloak if invulnerable armour and donned the lion's head as a helmet.

Leo is also said to be the lion in the tragic tale of the lovers Pyramus and Thisbe. In his Metamorphoses, Ovid tells how their parents forbade them to marry. The two talked secretly through a chink in the wall between their houses and one day made a plan to meet outside the city beside a certain mulberry tree with white berries. When Thisbe came to the meeting place, Pyramus was not there, but she was startled by a lion, bloody from a kill. As she ran away, her veil slipped and fluttered past the lion which snatched it with it's paw. When Pyramus arrived he saw Thisbe's torn veil, bloody from the Lion and assumed that his love had been killed. In anguish, he killed himself with his sword but at that moment, Thisbe ran back and flung herself on her dead lover's body before taking the sword and thrusting it into her own flesh. Their blood coloured the white mulberries red and they have remained this way ever since. Zeus placed the veil in the sky as Coma Berenices, floating down by the lion.

The name Regulus is believed to have originated with the astronomer Copernicus and means "the little king." In the ancient Sumerian civilization, Regulus was known as the Star of the King. Along the Euphrates, Regulus was known as "The Flame," or the "Red Fire." In the Ancient World, it was believed that this star made a contribution towards the heat of summer. Around 2300BC, the summer solstice was located near Regulus, meaning that around that period, the Sun was located near Regulus at the start of summer, and the combined heat of the Sun and Regulus was believed to produce the excessive heat of that season. This role later became that of Sirius from the precessional shift of the Earth's axis.

In the ancient Chinese zodiac, these stars were said to represent a horse.

Regulus is one of the four Royal Stars of the ancient Persians. The other three are Aldebaran, Antares and Fomalhaut.

Observers

Α Alpha Leonis, Regulus (10h98m +11deg 58') is a 1.4 magnitude blue-white class B7 star about 85 light years distant. It is 150 times more luminous than our Sun. Regulus has a surface temperature of about 12,500K. It has a diameter and mass of about three times our Sun. Regulus has an 8th magnitude companion of class K1. It appears as a deep yellow color. The companion too, is a double but with a magnitude of 13, they are a difficult pair to split.

M-65 - This galaxy is relatively large and bright, with a bright center and a stellar core. It is elongated in the north-south direction, and appears about 8'x2' in extent. It is in the same low power field of view as the next two objects.

M-66 - Smaller than M-65, this galaxy is wider, about 6'x3', and brighter. It also has a bright core, and is extended in the southeastern direction. Averted vision at reveals some mottling and indications of spiral structure.

NGC-3628 - Large, 10'x2', and oriented northwest-southeast, this object is faint overall, but averted vision shows a spindle-like shape with hints of a dust lane on the southwest side. A very interesting galaxy.

M-95 - Round, about 3' in diameter with a bright core surrounded by a faint halo. This is a barred spiral, but on a recent less-than-perfect night in Oklahoma, I failed to see this structure.

M-96 - This galaxy is ovoid, 4'x3', extended north-south with a bright core. Its core is large and non-stellar, about 1' in diameter.

M-105 - An elliptical galaxy, this object is relatively bright and appears round, about 3' in diameter, and has a bright central core.

NGC-2903 - Large and relatively bright, this galaxy appears to be about 8'x4', extended NNE-SSW, with a large, 1'x1' core. Some mottling is noticeable, and a darker area was noted on the western side.

Γ Gamma Leonis - This is a fine double star, although medium powers may be needed to split it. It shows a pretty pair of almost equally bright yellow stars.

Wolf 359 - This is a faint red dwarf star that would be unremarkable except that it is one of our closest neighbors in space. Only Alpha Centauri and Barnard's star are closer. It is one of the least luminous stars known, shining with the luminosity of about 1/63,000 that of the sun. It has only about 8% the mass of the sun and is approximately the size of Jupiter. To find it, use a chart such as that in Burnham's Celestial Handbook, and be patient: it shines at a magnitude of 13.6.


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Kathy Miles, Author, and Chuck Peters, Systems Administrator
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