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Constellations:
Libra -The Scales

Genitive: Librae
Abb: Lib
Dec: -0.3 to -29.9
RA:  14hr 18min to 15hr 59min

Continuing our journey along the ecliptic we move south of the celestial equator to Libra.

The Scales are the only Zodiac sign of a non-living object. The Romans gave them their place in the heavens during the 1st century BC. They saw this group of stars as the Scales of Justice held by Astraed (Virgo). Prior to the Romans, they were considered to be the northern and southern claws of Scorpio by the Greeks and the Arabs.

2000 years ago, when astrology was just getting it’s start, it was considered one of the four cardinal signs marking the changing of the seasons. At that time the path of the sun crossed the celestial equator in Libra in the autumn. Since then, due to a phenomenon known as precession, which is the product of the slow wobble of the Earth’s axis (it takes 25,725 years to complete one revolution) the autumnal equinox has moved into Virgo.

Libra is the seventh sign of the Zodiac and has two bright stars. Beta (b) Librae named Zubeneschamali (zoo-BEN-ess-sha-MAY-lee) or northern claw and Alpha (a) Librae named Zubenelgenubi (zoo-BEN-el-je-NEW-be) known as the southern claw. Hindu astronomers called the area between the two stars, the Celestial Gateway since the sun, moon and planets pass through this gateway as they travel the ecliptic. On my planisphere Libra appears as a trapezoid rather than scales. Look for it when it is highest in the sky at 10:00pm around the middle of June in the area between Scorpio and Virgo.

Exploring in Virgo

There are no Messier objects in Libra so this month’s star hops are not too good for small scopes or binoculars. M5 is 11° north of b Librae in the constellation of Serpens Caput so you have at least one thing to look for this month. M5 is the largest globular cluster on the Messier list and its location is shown on most planispheres.

From M5 move south to b Librae to start our tour. From b move 2 degrees north-northwest to 19 Delta (d) Librae, this is an Algol-type eclipsing spectroscopic binary variable. The primary varies in brightness over a 2-½ day period and its companion located 4 ½ million miles away partly eclipses it each revolution.

One degree north of d Librae is NGC 5812 an E1-type galaxy. This galaxy appears as a round fuzzy ball in pictures with no detail that I could see.

About 10° south of b Librae is a very loose globular cluster, NGC 5897, with a magnitude of about 10.

Return to your telrad and find a Librae on the southern side of the gateway. a Librae is really a pair of stars separated by 231 arcsec. About 1 ½ degrees southeast of a there are a pair of galaxies NGC 5796 and NGC 5793. NGC 5796 is an EO-type galaxy that looks like a fuzzy star. NGC 5793 is a Sb-type galaxy with a small narrow core that makes it hard to find.

This is all that I could find for Libra but we will have a lot more to find as we get into summer.

Happy Star-Hopping...Eric Reichenbach

Copyrighted © 2000 by Stockton Astronomical Society
Lasted Updated: 11/27/2000
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