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Deutsch: Vergleich zweier verschiedener Definitionen des tropischen Jahres (von Frühlingsäquinoktium zu Frühlingsäquinoktium, bzw. Zeit, welche die mittlere Sonne für 360° auf der Ekliptik braucht) mit der Länge des Gregorianischen Kalenderjahres, unter Berücksichtigung der langsamer werdenden Erdrotation.
English: Comparing two different definitions of the tropical year (from spring equinox to spring equinox, and time needed by the mean sun for 360° on the ecliptic) with the length of the Gregorian calendar year, allowing for the slowing-down of the Earth's rotation.
- Source: drawn by myself, using the orbital data provided by J. Meeus: More Mathematical Astronomy Morsels, Willmann-Bell 2002, chapter 63 (and due to Simon et al., 1994). The "360°" curve is the reciprocal of the instantaneous rate of change of the sun's mean longitude, expressed in mean solar days per 360°. The green curve is the time interval (expressed in mean solar days) needed by the sun's ecliptical longitude (calculated from the mean orbital elements) for one full revolution, starting and ending at the spring equinox. Conversion from ephemeris days to mean solar days assumes that the long-term trend in the increase of the length-of-day is (1.7+-0.05) milliseconds per century, see F.R. Stephenson: Historical Eclipses and Earth's Rotation, Cambridge University Press, Cambridge 1997.
- Date: 2006 APR 26
- Author: Sch
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current | 22:36, 3 May 2006 | 1,000×600 (10 KB) | Sch | |
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