Libra
Libra is a constellation located in the zodiac, represented symbolically as a set of scales, which reflects its association with balance and justice. It is best observed during June and July in the Northern Hemisphere and can be found between the constellations of Virgo and Scorpius. Historically, Libra has roots in ancient civilizations, where it was recognized for its significance in agricultural practices, as farmers relied on its visibility to determine planting and harvesting times. The name "Libra" originates from Latin, meaning "weighing scales," and it is unique among zodiac constellations as it represents an inanimate object rather than an animal or person.
Libra's brightest stars include beta Librae, alpha Librae, and sigma Librae, which form a triangular shape indicative of the scales. The constellation is also linked to the concept of justice, with its imagery deeply intertwined with the goddess of justice in Roman culture. Moreover, astronomers have discovered several exoplanets within the area of Libra, particularly orbiting the star Gliese 581, highlighting its ongoing relevance in astronomical research. This constellation's rich history and cultural significance continue to captivate those who gaze at the night sky.
Libra
FIELDS OF STUDY: Stellar Astronomy; Observational Astronomy
ABSTRACT: The constellation Libra is a grouping of stars and part of the zodiac. The constellation represents a balance scale, with two pans hanging from a center beam. Humans have used constellations such as Libra for millennia to track the seasons and tell the time of year. Scientists study constellations today mainly to name and track the stars that make up the patterns. By studying constellations and their stars, scientists can learn more about the galaxy and the universe.
Libra and Other Constellations
Constellations are patterns of stars that can be seen in the night sky from Earth. Humans have been identifying constellations for tens of thousands of years. People from different cultures grouped the stars in different constellations and gave them different names. The ancient Greeks described forty-eight constellations. European scientists in the sixteenth and seventeenth centuries saw other constellations. In 1930, Eugène Delporte listed these constellations for the International Astronomical Union (IAU). The IAU list of eighty-eight constellations is used by astronomers around the world. They use the constellations to identify and keep track of the stars.
Libra is one of the constellations in the zodiac. The zodiac is a group of twelve constellations that appear in a specific section of the night sky. People from ancient civilizations thought these constellations were special because it appears as though the sun travels within them. Although modern scientists know that Earth moves around the sun, giving the illusion that the sun is moving, people still enjoying looking for the constellations in the zodiac in the night sky.
Attributes of Libra
People in the Northern Hemisphere can view Libra best during June and July. It is located in the southwest quadrant in the Northern Hemisphere in the summer between Virgo in the west and Scorpius to the east. It is also close to the constellations Hydra, Ophiuchus, and Lupus.
The brightest stars in the Libra constellation are beta Librae (Zubeneschamali), alpha Librae (Zenelgenubi), and sigma Librae (Brachium). The drawn image of the constellation is a balance scale, with a central triangle or beam from which hang two pans. According to the IAU, alpha Librae, beta Librae, and gamma Librae (Zubenelakrab) form a triangle that represents the top of Libra’s scale. Other astronomers draw the triangle through alpha Librae, beta Librae, and sigma Librae. The constellation also includes upsilon Librae, tau Librae, and a number of other stars. Libra is one of the dimmest constellations in the zodiac.
History of Libra
People have been viewing the stars and identifying grouping of stars for tens of thousands of years. People first developed constellations for a number of reasons. Scientists believe that people identified some constellations according their religious beliefs. Other people developed constellations to help them with farming. These people noticed that the constellations were visible in the same spot in the sky at particular times of year. At this time, people did not have calendars, so farmers used the constellations to mark when to plant and harvest their crops.
The Sumerians called the constellation Zib-ba An-na, meaning "balance of heaven." Zib-ba An-na sounded like the Arabic and Akkadian words that mean both "weighing scale" and "scorpion." The constellation was once called Chelae Scorpionis ("claws of a scorpion"). In fact, the names of Libra’s stars Zubeneschamali and Zubenelgenubi translate as "northern claws" and "southern claws," respectively.
Researchers believe that Roman astronomers identified Libra in the first century BCE. In Latin, libra means "weighing scales." To the Romans, the constellation Libra depicted the scales held by the goddess of justice. It also stood for balance because at that time the sun shone in front of the constellation on the autumnal equinox, when there are equal amounts of day and night. Libra is the only constellation in the zodiac that represents an inanimate object instead of an animal or a person.
Studying Libra and Other Constellations
Between 2007 and 2010, scientists announced that they had found a number of exoplanets (planets outside Earth’s solar system) orbiting the star Gliese 581 in Libra. Two of those exoplanets, Gliese 581c and Gliese 581d, are much larger than Earth and located within the star’s habitable zone. This is a region at the optimal distance from the star that could allow for the formation of liquid water, a key ingredient for life. That does not mean the planets have liquid water or life, it is just that conditions are right for water to exist. Astronomers have found thirty-one exoplanets in Libra as of 2022.
PRINCIPAL TERMS
- celestial equator: the imaginary line above Earth’s equator that halves the celestial sphere; it is equally distant from the celestial poles.
- circumpolar constellation: a pattern of stars that appear in the night sky near a celestial pole and can be seen all night long, year-round.
- constellation: a pattern of stars that can be seen in the night sky from Earth.
- declination: the north-south position of a celestial body relative to the celestial equator expressed in degrees of arc.
- International Astronomical Union: a worldwide professional association of astronomers who conduct research and seek to educate others about astronomy. It sets the rules for naming celestial bodies and features on them and defines scientific constants of importance to astronomy.
- right ascension: the east-west position of a celestial body defined in relation to the celestial equator and expressed in hours and minutes, not degrees of arc.
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