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The Constellation Libra - Myths and Stars - Zodiac Series
Looking at the evening sky between September 22 and October 22 of each year, this constellation is situated between two other constellations, Virgo and Scorpius. It’s harder to see than Virgo, as the stars in this constellation aren’t extremely bright. In fact, it’s one of the faintest constellations of the zodiac.
If you like to look at the evening sky, you might know that studying the night sky is called astronomy. It's an incredibly fascinating branch of science!
This constellation lies on the zodiac – an imaginary circle where twelve constellations lie upon a celestial sphere in the sky. The sun passes through each constellation along this circle every year. The planets in our solar system travel through these constellations as well.
Libra has a mixed mythological history, with the Greeks, ancient Hebrews and Romans all playing a role. It’s the only constellation in the zodiac that doesn’t represent an animal or a person.
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Mythology of Libra
Long ago, the ancient Hebrews thought of this sign as a “balance.” In fact, the name Libra means “scale.”
Initially, Libra wasn’t its own constellation. The Greeks thought of it as an extension to the constellation Scorpius (also known as Scorpio). They considered the stars in Libra to be the claws of Scorpius. Over time, however, they began to change their thinking, saying that it symbolized Mochus, who invented weights and measures. This was, perhaps, because of Roman influence.
The Romans were the ones who coined the term, “Libra.” The goddess Aestraea used to rule the world. She was the godess of Justice before she became disillusioned with the people of the earth and went up to the heavens. Libra was her balance, where she would weigh the good deeds of her human subjects and determine their fates.
The Romans extended this meaning of “balance” to represent the equal hours of day and night during the autumnal equinox. Just as the goddess Aestraea stood for Justice, so, too, did the Romans also see this constellation as a sign of justice and harmony.
In ancient times, the sun used to pass through Libra at the time of equinox, but now it passes through Virgo, near the star η Virginis.
Ancient farmers would look to the stars in Libra to indicate the correct time for planting winter grains and cover crops.
Star Names in Libra
green star, especially with binoculars
eclipsing variable, Algol-type
The Stars of Libra
Looking for Scorpius or Virgo in the sky, an observer should be able to find Libra, though the stars are somewhat faint. The sun passes through this constellation between October 31 and November 23.
α Librae and β Librae are the two brightest stars in this constellation, with a magnitude of 3. This means that on a scale of 0-10, with 0 being the brightest, and 6 being about the faintest stars that the human eye can see. Beyond that, astronomers must use telescopes to see fainter stars.
α Librae and β Librae also have interesting Arabic names: Zubenelgenubi and Zubeneschamali, respectively. They mean “southern and northern claw.”
α Librae is a double star. The first star, is the one with a magnitude of 3, and other has a magnitude of 5. With binoculars, it’s possible to see both of them.
β Librae is a green star, but some would argue that it looks more “white” than anything else. Astronomers can see this with the naked eye. It’s 100 times brighter than the Sun. This particular star is actually getting closer to Earth, approaching at about 23 miles per second.
In ancient times, Ptolemy reported β Librae as extremely bright, comparing it to Antares in Scorpius. It’s not nearly that bright now, suggesting that its light levels have varied dramatically over the millennia.
This constellation has other stars that are much fainter. The table below illustrates those stars and their magnitude, and any interesting attributes about them.
The Book of Constellations. Kerrod, Robin. Barron's: Hauppauge, NY. 2002.
Field Book of the Skies. Olcott, William T. G.P. Putnam's Sons: NY. 1974.
Guide to Stars and Planets. Moore, Sir Patrick. Firefly Books: Buffalo, NY. 2005.
Seasonal Star Charts. Hubbard Scientific Company. 1972.