Key to Lunar Eclipse Maps (original) (raw)

Each lunar eclipse has two diagrams associated with it along with data pertinent to the eclipse. The top figure shows the path of the Moon through Earth's penumbral and umbral shadows. Above this figure are listed the instant of conjunction in right ascension of the Moon with Earth's shadow axis and the instant of greatest eclipse, expressed as both Universal Time and Julian Date. The penumbral and umbral magnitudes are defined as the fraction of the Moon's diameter immersed in the two shadows at greatest eclipse. The radii of the penumbral and umbral shadows 'P. Radius' and 'U. Radius' are also listed. 'Gamma' is the minimum distance in Earth radii of the Moon's center from Earth's shadow axis at greatest eclipse, while 'Axis' is the same parameter expressed in degrees. The Saros series of the eclipse is listed, followed by a pair of numbers. The first 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 the semi or half durations of the penumbral, umbral (partial) and total eclipses. Below them are the Sun/Moon ephemerides used in the predictions, followed by the extrapolated value of T (the difference between Terrestrial Dynamical Time and Universal Time). To the lower right are the contact times of the Moon with Earth's penumbral and umbral shadows, defined as follows:

P1 -	Instant of first exterior tangency of Moon with Penumbra.
    (Penumbral Eclipse Begins)
U1 -	Instant of first exterior tangency of Moon with Umbra.
    (Partial Umbral Eclipse Begins)
U2 -	Instant of first interior tangency of Moon with Umbra.
    (Total Umbral Eclipse Begins)
U3 -	Instant of last interior tangency of Moon with Umbra.
    (Total Umbral Eclipse Ends)
U4 -	Instant of last exterior tangency of Moon with Umbra
    (Partial Umbral Eclipse Ends)
P4 -	Instant of last exterior tangency of Moon with Penumbra.
    (Penumbral Eclipse Ends)

The bottom figure is an equidistant cylindrical projection map of Earth which shows the regions of visibility for each stage of the eclipse. In particular, the moonrise/moonset terminator is plotted for each contact and is labeled accordingly. The point where the Moon is in the zenith at greatest eclipse is indicated by an asterisk symbol. The region which is completely unshaded will observe the entire eclipse while the darkly shaded area will witness none of the event. The remaining lightly shaded areas will experience moonrise or moonset while the eclipse is in progress. The shaded zones east of the '*' will witness moonset before the eclipse ends while the shaded zones west will witness moonrise after the eclipse has begun.

The eclipse predictions were generated on a Macintosh Quadra using algorithms developed from the Explanatory Supplement [1974]. The solar and lunar ephemerides were generated from Newcomb [1895] and the ILE [1954], respectively. The diameter of the umbral shadow was enlarged by 2% to compensate for Earth's atmosphere, and the effects of oblateness have also been included. All predictions are with respect to the Moon's center of mass; no corrections have been made for the center of figure.

All calculations, figures, maps and data are by Fred Espenak, and he assumes full responsibility for their accuracy. These figures are based on maps first published in Fifty Year Canon of Lunar Eclipses: 1986 - 2035.

References

Espenak, F., 1989, Fifty Year Canon of Lunar Eclipses: 1986-2035, Sky Publishing Corp., Cambridge, MA.
Explanatory Supplement to the Astronomical Ephemeris and the American Ephemeris and Nautical Almanac, 1974, Her Majesty's Nautical Almanac Office, London.
Improved Lunar Ephemeris 1952-1959, 1954, U.S. Naval Observatory, Washington, DC.
Meeus, J. and H. Mucke, 1979, Canon of Lunar Eclipses: -2002 to +2526, Astronomisches Buro, Wien.
Newcomb, S., 1895, "Tables of the Motion of the Earth on its Axis Around the Sun", Astron. Papers Amer. Eph., Vol. 6, Part I.

WebMaster: Fred Espenak Planetary Systems Branch - Code 693e-mail: espenak@lepvax.gsfc.nasa.gov NASA/Goddard Space Flight Center, Greenbelt, Maryland 20771 USA

Last revised: 2001 Jul 11 - F. Espenak