Solar Eclipse Figures

Fred Espenak, NASA's GSFC

For each solar eclipse, an orthographic projection map of Earth shows the path of penumbral eclipse. North is to the top in all cases and the daylight terminator is plotted for the instant of greatest eclipse [1]. An asterisk (*) indicates the sub-solar point [2] on Earth.

The limits of the Moon's penumbral shadow delineate the region of visibility of the partial solar eclipse. This irregular or saddle shaped region often covers more than half of the daylight hemisphere of Earth and consists of several distinct zones or limits. At the northern and/or southern boundaries lie the limits of the penumbra's path. Partial eclipses have only one of these limits, as do central eclipses when the Moon's shadow axis falls no closer than about 0.45 radii from Earth's centre. Great loops at the western and eastern extremes of the penumbra's path identify the areas where the eclipse begins/ends at sunrise and sunset, respectively. If the penumbra has both a northern and southern limit, the rising and setting curves form two separate, closed loops. Otherwise, the curves are connected in a distorted figure eight. Bisecting the 'eclipse begins/ends at sunrise and sunset' loops is the curve of maximum eclipse at sunrise (western loop) and sunset (eastern loop). The points P1 and P4 mark the coordinates where the penumbral shadow first contacts (partial eclipse begins) and last contacts (partial eclipse ends) Earth's surface. These correspond to the coordinates where the penumbral shadow cone becomes internally tangent to Earth's disk.

A curve of maximum eclipse is the locus of all points where the eclipse is at maximum at a given time. Curves of maximum eclipse are plotted at each half-hour Universal Time. They generally run between the penumbral limits in the north/south direction, or from the 'maximum eclipse at sunrise and sunset' curves to one of the limits. The curves of constant eclipse magnitude [3] delineate the locus of all points where the magnitude at maximum eclipse is constant. These curves run exclusively between the curves of maximum eclipse at sunrise and sunset. Furthermore, they are quasi parallel to the northern/southern penumbral limits. In fact, the northern and southern limits of the penumbra can be thought of as curves of constant magnitude of 0.0. The adjacent curves are for magnitudes of 0.2, 0.4, 0.6 and 0.8.

Greatest eclipse [1] is defined as the instant when the axis of the Moon's shadow passes closest to Earth's center. For partial eclipses, the shadow axis misses Earth entirely, so the geographic location of greatest eclipse (marked by an asterisk) lies on the day/night terminator and the Sun appears on the horizon.

Data pertinent to the eclipse appear with each map. At the top are listed the instant of ecliptic conjunction of the Sun and Moon (i.e., New Moon) and the instant of greatest eclipse, expressed in Terrestrial Dynamical Time and Universal Time. The eclipse magnitude is defined as the fraction of the Sun's diameter obscured by the Moon at greatest eclipse. For central eclipses (total or annular), the magnitude is replaced by the geocentric ratio of diameters of the Moon and the Sun. Gamma is the minimum distance of the Moon's shadow axis from Earth's center in Earth radii at greatest eclipse. The Saros series of the eclipse is listed, followed by the member position. The first member number identifies the sequence position of the eclipse in the Saros, while the second is the total number of eclipses in the series.

In the upper left and right corners are the geocentric coordinates of the Sun and the Moon, respectively, at the instant of greatest eclipse. They are:

R.A. - Right Ascension
Dec. - Declination
S.D. - Apparent Semi-Diameter
H.P. - Horizontal Parallax

To the lower left are exterior/interior contact times of the Moon's penumbral shadow with Earth, which are defined:

P1 - Instant of first exterior tangency of Penumbra with Earth's limb. (Partial Eclipse Begins)
P4 - Instant of last exterior tangency of Penumbra with Earth's limb. (Partial Eclipse Ends)

Not all eclipses have P2 and P3 penumbral contacts. They are only present in cases where the penumbral shadow falls completely within Earth's disk.

At bottom left are a list of parameters used in the eclipse predictions, while bottom right gives the Moon's geocentric libration (optical + physical) at greatest eclipse.

The solar eclipse figures are updates of versions originally published in Fifty Year Canon of Solar Eclipses: 1986-2035 (Espenak, 1988).


[1] The instant of greatest eclipse occurs when the distance between the Moon's shadow axis and Earth's geocenter reaches a minimum.

[2] The sub-solar point is the geographic location where the Sun appears directly overhead (zenith).

[3] Eclipse magnitude is defined as the fraction of the Sun's diameter occulted by the Moon

Return to Eclipses During:
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2010 Jul 23