Colure

Orange = equinoctial colure
Blue = solstitial colure

G = equinoctial colure
H = solstitial colure

Colure, in astronomy, is either of the two principal meridians of the celestial sphere. The term is now rarely used and may be considered obsolete.

Equinoctial colure

The equinoctial colure is the meridian or great circle of the celestial sphere which passes through the celestial poles and the two equinoxes: the first point of Aries and the first point of Libra. It is the great circle consisting of all points on the celestial sphere with Right Ascension equal to 0 hours or 12 hours (equivalent to RA 0° / 180°).

The equinoctial colure passes through the following constellations:

Solstitial colure

The solstitial colure is the meridian or great circle of the celestial sphere which passes through the poles and the two solstices: the first point of Cancer and the first point of Capricorn. It is the great circle consisting of all points on the celestial sphere with Right Ascension equal to 6 hours or 18 hours (equivalent to RA 90° / 270°).

The solstitial colure passes through the following constellations:

See also

• Celestial coordinate system
• Ecliptic
• Celestial sphere
• Right ascension
• Equinox
• Solstice

References

• This article incorporates text from a publication now in the public domain: 
• Harley, John Brian; Woodward, David (1987). Cartography in the Traditional Islamic and South Asian Societies. The History of cartography. Vol. 2. University of Chicago Press. p. 28. ISBN 978-0-226-31635-2. OCLC 13456456. OL 9455351M.
• Geminus; Evans, James; Berggren, J. L. (2006). Geminos's Introduction to the phenomena: a translation and study of a Hellenistic survey of astronomy. Princeton University Press. p. 130. ISBN 978-0-691-12339-4. OCLC 70232402. OL 15978783M.
• Ovason, David (1999). The Secret Architecture of our Nation's Capital. HarperCollins. p. 98. ISBN 978-006095368-3. OCLC 50409366.
• Kaler, Jim. "Pi Aurigae." Pi Aurigae. N.p. 22 Feb. 2008. Web.