double CalendarAstronomer::eclipticObliquity | ( | ) | ` [private]` |

Return the obliquity of the ecliptic (the angle between the ecliptic and the earth's equator) at the current time. This varies due to the precession of the earth's axis.

**Returns:**- the obliquity of the ecliptic relative to the equator, measured in radians.

Definition at line 1403 of file astro.cpp.

References getJulianDay().

Referenced by eclipticToEquatorial().

{ if (isINVALID(eclipObliquity)) { const double epoch = 2451545.0; // 2000 AD, January 1.5 double T = (getJulianDay() - epoch) / 36525; eclipObliquity = 23.439292 - 46.815/3600 * T - 0.0006/3600 * T*T + 0.00181/3600 * T*T*T; eclipObliquity *= DEG_RAD; } return eclipObliquity; }

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