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Unformatted text preview: Precession of the Equinoxes The Earths axis precesses like a top, once about every 26000 years. Precession changes the positions in the sky of the celestial poles and the equinoxes Polaris wont always be the North Star. Lunar Motion We always see the same face of moon because rotation period = orbital period. Eclipses Moons orbit tilted 5 to ecliptic plane.-Crosses ecliptic plane only at the two nodes.-Eclipse possible only when full/new occur near nodes.-Orbit tilt must be in position where the orbit passes in front or back of Earth at new/full moon. Moons orbit intersects the ecliptic at new moon Solar eclipse Within umbra Total solar eclipse Within penumbra Partial solar eclipse at full moon Lunar eclipse...
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- Winter '08