47
longer than that between the summer solstice and the autumnal equinox, for example. Thus, comparing solstice and equinox dates given by the Babylonian scheme
with modern computation we should find differences in the accuracy of the dates of
the four solstices and equinoxes. Indeed the dates of the autumnal equinoxes are
consistently closer to the dates given by modern computation of the moment of the
astronomical equinox than for either of the two solstices or the vernal equinox
(Kugler, 1909–1924: 606). This fact might suggest that the scheme was tethered to
an observed autumnal equinox in some year, although we cannot exclude the possibility that it is just chance that the dates of the autumnal equinox agree better with
modern computation. Whether it was an autumnal equinox, the vernal equinox, or
either of the two solstices, however, we still do not know how the date of that phenomenon was determined.
All of the reports of solstices and equinoxes in the Astronomical Diaries simply
state the date on which the phenomenon took place. Interestingly, these are always
recorded as daytime events, highlighting their connection with the sun; none are
recorded as having taken place during the night. Short time measurements of when
during the day the solstice or equinox occurred are never given. This contrasts with
the situation in later Greek astronomy: the solstices and equinoxes reported in
Ptolemy’s Almagest occur both during the day and night and are usually accompanied by a statement of the approximate time of day when the phenomenon took
place (Perdersen, 1974: 129). The reason, of course, is that for Greek astronomers
such as Hipparchos and Ptolemy the equinoxes were defined by the sun being at one
of the two points of intersection of the ecliptic and the celestial equator and the
solstices as the points separated from the equinoxes by 90° on the ecliptic. For the
Babylonians, defining the solstices and equinoxes in terms of the length of day and
night, a time during the day when the phenomenon occurred would be meaningless.
In essence the solstices and equinoxes lasted for the whole day, rather than a specific moment.
This discussion of the way in which the solstices and equinoxes were defined in
Mesopotamia has hopefully provided one clear example of the importance of not
assuming that astronomical concepts are not universal. Even in the case of astronomies where there is clear evidence of extensive contact, such as between Babylonian
and Greek astronomy, underlying concepts can be subtly different and we must not
impose our understanding of one conception onto the other culture (for a similar
example, see my discussion of the differences between Greek and Babylonian concepts of the zodiac and the ecliptic in Steele, 2007).
References
Al-Rawi, F. N. H., & George, A. R. (1991–1992). Enūma Anu Enlil XIV and other early astronomical tables. Archiv für Orientforschung, 38–39, 52–73.
Brack-Bernsen, L. (2007). The 360-Day Year in Mesopotamia. In J. M. Steele (Ed.), Calendars
and Years: Astronomy and Time in the Ancient Near East (pp. 83–100). Oxford: Oxbow Books.
Their Equinox: Mesopotamian Conceptions of Solstices and Equinoxes
longer than that between the summer solstice and the autumnal equinox, for example. Thus, comparing solstice and equinox dates given by the Babylonian scheme
with modern computation we should find differences in the accuracy of the dates of
the four solstices and equinoxes. Indeed the dates of the autumnal equinoxes are
consistently closer to the dates given by modern computation of the moment of the
astronomical equinox than for either of the two solstices or the vernal equinox
(Kugler, 1909–1924: 606). This fact might suggest that the scheme was tethered to
an observed autumnal equinox in some year, although we cannot exclude the possibility that it is just chance that the dates of the autumnal equinox agree better with
modern computation. Whether it was an autumnal equinox, the vernal equinox, or
either of the two solstices, however, we still do not know how the date of that phenomenon was determined.
All of the reports of solstices and equinoxes in the Astronomical Diaries simply
state the date on which the phenomenon took place. Interestingly, these are always
recorded as daytime events, highlighting their connection with the sun; none are
recorded as having taken place during the night. Short time measurements of when
during the day the solstice or equinox occurred are never given. This contrasts with
the situation in later Greek astronomy: the solstices and equinoxes reported in
Ptolemy’s Almagest occur both during the day and night and are usually accompanied by a statement of the approximate time of day when the phenomenon took
place (Perdersen, 1974: 129). The reason, of course, is that for Greek astronomers
such as Hipparchos and Ptolemy the equinoxes were defined by the sun being at one
of the two points of intersection of the ecliptic and the celestial equator and the
solstices as the points separated from the equinoxes by 90° on the ecliptic. For the
Babylonians, defining the solstices and equinoxes in terms of the length of day and
night, a time during the day when the phenomenon occurred would be meaningless.
In essence the solstices and equinoxes lasted for the whole day, rather than a specific moment.
This discussion of the way in which the solstices and equinoxes were defined in
Mesopotamia has hopefully provided one clear example of the importance of not
assuming that astronomical concepts are not universal. Even in the case of astronomies where there is clear evidence of extensive contact, such as between Babylonian
and Greek astronomy, underlying concepts can be subtly different and we must not
impose our understanding of one conception onto the other culture (for a similar
example, see my discussion of the differences between Greek and Babylonian concepts of the zodiac and the ecliptic in Steele, 2007).
References
Al-Rawi, F. N. H., & George, A. R. (1991–1992). Enūma Anu Enlil XIV and other early astronomical tables. Archiv für Orientforschung, 38–39, 52–73.
Brack-Bernsen, L. (2007). The 360-Day Year in Mesopotamia. In J. M. Steele (Ed.), Calendars
and Years: Astronomy and Time in the Ancient Near East (pp. 83–100). Oxford: Oxbow Books.
Their Equinox: Mesopotamian Conceptions of Solstices and Equinoxes