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first point of Libra

(≏) The point on the celestial sphere diametrically opposite the first point of Aries. It is the same as the autumnal equinox. It has right ascension 12h and declination zero. It is the ...

first point of Libra

first point of Libra   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018

... point of Libra ( symbol ♎ ) The point on the celestial sphere diametrically opposite the first point of Aries . It is the same as the autumnal equinox. It has right ascension 12h and declination zero. It is the point at which the Sun passes from north to south of the celestial equator, which happens on September 22 or 23 each year. Because of precession , it no longer lies in Libra but in neighbouring...

first point of Libra

first point of Libra  

(≏) The point on the celestial sphere diametrically opposite the first point of Aries. It is the same as the autumnal equinox. It has right ascension 12h and declination zero. It is the point at ...
hed

hed   Reference library

The Oxford Companion to Chaucer

Reference type:
Subject Reference
Current Version:
2005

...) heed , heved , head . In A Treatise on the Astrolabe and Equatorie of the Planetis , the word denotes the first degree or beginning of the sign (L. caput Arietis , etc.) . It is used in practice of only four signs, but that is because they are of special importance. The four are Aries, Cancer, Libra, and Capricorn. The Sun's entering those signs marks the commencement of the four seasons, spring, summer, autumn, and winter. The head of Aries is the reference point from which longitudes are measured along the ecliptic . ( See also months and...

ecliptic

ecliptic   Quick reference

The Oxford Companion to Ships and the Sea (2 ed.)

Reference type:
Subject Reference
Current Version:
2007
Subject:
History, Social sciences
Length:
122 words
Illustration(s):
1

...the Greek ekleipsis , disappearance, the apparent path of the sun among the stars which is a great circle inclined to the celestial equator at an angle of about 23° 27′. It is so named because, for an eclipse of the sun or moon to occur, the moon must lie on or near the ecliptic. It intersects the celestial equator, or equinoctial , twice during the year at the equinoxes; on 21 March at the ‘first point of Aries’, which is 0° Right Ascension, and on 23 September at the ‘first point of Libra’, at 180° Right Ascension, and is furthest from the equator...

equinox

equinox   Quick reference

A Dictionary of Astronomy (3 ed.)

Reference type:
Subject Reference
Current Version:
2018

... Either of the two points at which the Sun’s apparent yearly path (the ecliptic) intersects the celestial equator; or the dates on which this occurs—on March 20 ( vernal equinox ) and September 22 or 23 ( autumnal equinox ). These points are also known as the first point of Aries and the first point of Libra . When the term ‘equinox’ is used without qualification, the vernal (spring) equinox is meant. Around the time of the equinoxes, night and day are equal in length the world over. The equinox is not a fixed point, but moves because of precession ...

right ascension

right ascension   Quick reference

A Dictionary of Weights, Measures, and Units

Reference type:
Subject Reference
Current Version:
2004

...the segment of the sky from 0 to 2 h (0 to 30°), Taurus from 2 to 4 h (30 to 60°), et seq. through Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, and Aquarius to Pisces at 22 to 24 h (330 to 360°). Greenwich Hour Angle ( GHA ) is a similar concept to right ascension, being the west longitude (0° to 360°) of the point directly below the celestial body at any instant. Since the GHA of any body equals the GHA of the First Point of Aries plus (360° minus RA of the body), the latter referred to as the Sidereal Hour Angle ( SHA ) of the body,...

zodiac

zodiac   Quick reference

A Dictionary of Weights, Measures, and Units

Reference type:
Subject Reference
Current Version:
2004

...band of our sky within which the Sun and its other planets appear to travel, divided traditionally into twelve equal-sized segments named sequentially Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpio, Sagittarius, Capricorn, Aquarius, and Pisces. However, while each of these is classically the name of a specific star pattern, still used, along with 76 outside this band, as one of the variously sized polygons (‘constellations’) into which the heavens are fixedly divided, they have a distinct meaning for the zodiac. The apparent annular path of the Sun...

algebra

algebra   Reference library

The Oxford Dictionary of the Renaissance

Reference type:
Subject Reference
Current Version:
2005
Subject:
History, Early Modern History (1500 to 1700)
Length:
1,004 words

...‘radix’, first appear in the work of Michael Stiefel ( 1544 ). The equals sign (=), apparently derived from the symbol for the zodiac sign Libra (the Balance), first appears in the work of Robert Recorde . However, algebra books, being written in the vernacular, had only local circulation, so such symbols were not adopted either universally or rapidly. Viète was the first to use notation to distinguish between the unknown and given quantities: he used vowels for the former and consonants for the latter; Descartes ( 1637 ) introduced the use of letters from...

astrology

astrology   Reference library

The Oxford Companion to the Mind (2 ed.)

Reference type:
Subject Reference
Current Version:
2006
Subject:
Science and technology, Psychology, Philosophy
Length:
1,735 words

...had allowed himself too much leeway of interpretation. Gauquelin's book, Songes et mensonges de l'astrologie ( 1969 ), was a scathing attack on astrology, as its title (Dreams and Delusions of Astrology) indicates. Yet the unsatisfactoriness of Krafft's experimental method led Gauquelin to devise a few simple tests of his own. He concentrated his analysis on two straightforward questions. The first was whether astrologers are correct in stating that people born under ‘odd’ signs of the zodiac—Aries, Gemini, Leo, Libra, Sagittarius, Aquarius—tend to be...

astrology

astrology   Reference library

Encyclopedia of the Middle Ages

Reference type:
Subject Reference
Current Version:
2005
Subject:
History, Early history (500 CE to 1500)
Length:
1,535 words
Illustration(s):
1

...world, in the field of the interpretation of major natural, political or religious events: hypothetical tempests of 1186 , linked to the presence of all the planets in the sign of Libra; Black Death of 1348 and Great Schism of 1378 , interpreted after the event as the consequences of the conjuctions of 1345 and 1365 , etc. As for comets, they usually foretold catastrophes, notably the coming death of some king or prince, and had done so since the early Middle Ages. Medieval astrology was thus never reduced to a set of techniques of prediction. It was...

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