
Lunar Limb Profile Window
The window displays the lunar limb profile during the eclipse from your location.
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Choose Display > Lunar Limb Profile…
Eclipse contact times, magnitude and duration of totality or annularity all depend on the angular diameters and relative velocities of the Moon and Sun. The Moon exhibits an irregular limb when seen in profile, due to its surface topography. Most eclipse calculations assume some mean radius that averages high mountain peaks and low valleys along the Moon’s rugged limb. Kaguya probe and Lunar Reconnaissance Orbiter data or Watts charts are used for higher accuracy in those calculations. The radial scale of the limb profile in the figure is exaggerated so that the true limb’s departure from the mean lunar limb is readily apparent. The mean limb with respect to the center of figure of Kaguya’s, Lunar Reconnaissance Orbiter or Watts’ data is shown as a turquoise dashed line along with the mean limb with respect to the center of mass shown as a solid red line. The position angles of second and third contacts are clearly marked with orange and green arrows (dotted for corrected contacts) along with the north pole of the Moon’s axis of rotation in blue, the north pole of the Sun’s axis of rotation in yellow and the observer’s zenith at mid-totality in mauve. A contextual menu, that can be invoked with a right click, will let you select various options:
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