[Chaos-l] Fwd: Historical solar eclipse maps
Jayme Hanzak
jhanzak at unctv.org
Fri Mar 4 12:38:52 EST 2011
From
Dr. Barbara Becker.
Jayme Hanzak
CHAOS President
CHAOS
P.O. Box 3001
Chapel Hill, NC 27514-0842
http://www.rtpnet.org/chaos/
-----------------------------
Dear Jayme, this message recently came in on the History of Astronomy listserv.
I thought you and some of your members would be interested in Zeiler's website.
Has anyone in the group begun to think about the 2017 eclipse? The
centerline will pass through SC.
all the best,
Barb.
>Date: Tue, 1 Mar 2011 15:21:33 -0700
>From: Michael Zeiler <eclipsemaps at gmail.com>
>Subject: Historical solar eclipse maps
>To: HASTRO-L at listserv.wvu.edu
>
>Greetings,
>
>I'm a new member to this list and I'd like to introduce my web site,
>www.eclipse-maps.com
>
>It's not yet complete, but it does contain a substantial number of
>historical solar eclipse maps and newly published eclipse maps, about 1,300
>maps in all. The two pages that presently have real content are the History
>and Gallery pages. The historical maps are presented in albums that are
>mostly organized in decadal ranges with commentary on the significant maps,
>personalities, and progress of that era. (Apologies if you have a slow
>internet connection; the albums may be slow to load because they contain
>many high-resolution images)
>
>I'm a cartographer and not a historian. For two years, I've been combining
>my professional skills with my personal interest in solar eclipses to
>produce new eclipse maps. My initial motivation was that I was not satisfied
>with many of the available solar eclipse maps. While our computerized
>technology makes it relatively easy for one to produce an eclipse map, the
>resulting cartographic products are often deficient. I then took an interest
>in the history of eclipse maps because many old solar eclipse maps have
>superb cartographic designs that modern cartographers can learn from. This
>interest and a budding collection of eclipse maps led to the creation of
>this web site two months ago. For me, this is applied history: I am directly
>learning from past masters to improve my craft.
>
>Eclipse maps are fascinating because they combine spatial and temporal
>information and are among the earliest maps to do so. Eclipse maps are also
>audacious because they give very precise forecasts that any interested
>person can act on to witness the greatest natural spectacle on earth. Edmund
>Halley's eclipse map of 1715 was perhaps the first to give reasonably
>precise and actionable predictions on a map in advance of a total solar
>eclipse.
>
>Some of the historical questions I'm interested in are:
>
>- What was the scientific and cultural milieu that produced the earliest
>known eclipse map of 1654 and sparked the flowering of eclipse maps of the
>early 18th century? While the phenomena of eclipses were well understood in
>antiquity by some such as Ptolemy, why did it take until the Enlightenment
>to conceptualize the idea of an eclipse map? And if Kepler's laws of
>planetary motion of the early 17th century were necessary, why the
>half-century gap before the first eclipse map?
>
>- There are several types of temporal data associated with an eclipse:
>timings of the four eclipse contacts and time of greatest eclipse, and
>durations of the total/annular phases as well as semidurations of the
>partial phases. A single map cannot reasonably present all of this data and
>eclipse maps instead present a subset of this temporal information. There is
>an interesting progression in the selection of temporal data that is
>displayed on historical eclipse maps. What guided this evolution of the
>presentation of temporal eclipse data?
>
>- Another eclipse feature that is frequently mapped is the magnitude of the
>partial phases of a solar eclipse. Early eclipse maps show isomagnitudes of
>"digits", divisions of the occulted fraction of the sun's diameter into
>twelfths. Then starting in the mid-19th century, the display of
>isomagnitudes on eclipse maps took a hiatus and were rarely present on
>eclipse maps. When isomagnitudes started reappearing on eclipse maps in the
>20th century, with only one exception that I've found, isomagnitudes on all
>eclipse maps since are divided into tenths or one-hundredths. What caused
>the hiatus of isomagnitude displays on eclipse maps? Was the conversion to
>tenths instead of twelfths ("digits") influenced by the movement of the
>adoption of SI units?
>
>- Since the areal coverage of eclipses span a sizable fraction of the
>earth's surface, selecting an appropriate map projection is a challenge. In
>the 19th century, it seems that the British Nautical Almanac preferred the
>Mercator projection, which has qualities useful for navigation but which is
>a generally poor choice for eclipse maps. The French Connaissance des Temps
>and the American Ephemeris tended to prefer the orthographic and
>stereographic projections. Many recent eclipse maps have reverted to the
>Mercator projection, a puzzling and poor choice. I think the second ever
>eclipse map of 1676 got it right; the stereographic projection is the best
>overall projection for mapping the full extent of an eclipse. There are
>clearly several factors involved: ease of construction of a projection,
>purpose of the enclosing document (usually almanacs), cultural preferences
>(and latitude of home region?).
>
>If anyone on this list has special knowledge on the history of eclipse maps,
>or access to maps and research which might be added to or referenced in the
>archive of www.eclipse-maps.com, I'd appreciate hearing from you.
>
>
>best regards, Michael Zeiler
>Santa Fe, New Mexico
--
Dr. Barbara J. Becker
History Department
200 Murray Krieger Hall
University of California, Irvine
Irvine California 92697
http://eee.uci.edu/clients/bjbecker
-----------------------------
Dear Jayme, this message recently came in on the History of Astronomy listserv.
I thought you and some of your members would be interested in Zeiler's website.
Has anyone in the group begun to think about the 2017 eclipse? The
centerline will pass through SC.
all the best,
Barb.
>Date: Tue, 1 Mar 2011 15:21:33 -0700
>From: Michael Zeiler <eclipsemaps at gmail.com>
>Subject: Historical solar eclipse maps
>To: HASTRO-L at listserv.wvu.edu
>
>Greetings,
>
>I'm a new member to this list and I'd like to introduce my web site,
>www.eclipse-maps.com
>
>It's not yet complete, but it does contain a substantial number of
>historical solar eclipse maps and newly published eclipse maps, about 1,300
>maps in all. The two pages that presently have real content are the History
>and Gallery pages. The historical maps are presented in albums that are
>mostly organized in decadal ranges with commentary on the significant maps,
>personalities, and progress of that era. (Apologies if you have a slow
>internet connection; the albums may be slow to load because they contain
>many high-resolution images)
>
>I'm a cartographer and not a historian. For two years, I've been combining
>my professional skills with my personal interest in solar eclipses to
>produce new eclipse maps. My initial motivation was that I was not satisfied
>with many of the available solar eclipse maps. While our computerized
>technology makes it relatively easy for one to produce an eclipse map, the
>resulting cartographic products are often deficient. I then took an interest
>in the history of eclipse maps because many old solar eclipse maps have
>superb cartographic designs that modern cartographers can learn from. This
>interest and a budding collection of eclipse maps led to the creation of
>this web site two months ago. For me, this is applied history: I am directly
>learning from past masters to improve my craft.
>
>Eclipse maps are fascinating because they combine spatial and temporal
>information and are among the earliest maps to do so. Eclipse maps are also
>audacious because they give very precise forecasts that any interested
>person can act on to witness the greatest natural spectacle on earth. Edmund
>Halley's eclipse map of 1715 was perhaps the first to give reasonably
>precise and actionable predictions on a map in advance of a total solar
>eclipse.
>
>Some of the historical questions I'm interested in are:
>
>- What was the scientific and cultural milieu that produced the earliest
>known eclipse map of 1654 and sparked the flowering of eclipse maps of the
>early 18th century? While the phenomena of eclipses were well understood in
>antiquity by some such as Ptolemy, why did it take until the Enlightenment
>to conceptualize the idea of an eclipse map? And if Kepler's laws of
>planetary motion of the early 17th century were necessary, why the
>half-century gap before the first eclipse map?
>
>- There are several types of temporal data associated with an eclipse:
>timings of the four eclipse contacts and time of greatest eclipse, and
>durations of the total/annular phases as well as semidurations of the
>partial phases. A single map cannot reasonably present all of this data and
>eclipse maps instead present a subset of this temporal information. There is
>an interesting progression in the selection of temporal data that is
>displayed on historical eclipse maps. What guided this evolution of the
>presentation of temporal eclipse data?
>
>- Another eclipse feature that is frequently mapped is the magnitude of the
>partial phases of a solar eclipse. Early eclipse maps show isomagnitudes of
>"digits", divisions of the occulted fraction of the sun's diameter into
>twelfths. Then starting in the mid-19th century, the display of
>isomagnitudes on eclipse maps took a hiatus and were rarely present on
>eclipse maps. When isomagnitudes started reappearing on eclipse maps in the
>20th century, with only one exception that I've found, isomagnitudes on all
>eclipse maps since are divided into tenths or one-hundredths. What caused
>the hiatus of isomagnitude displays on eclipse maps? Was the conversion to
>tenths instead of twelfths ("digits") influenced by the movement of the
>adoption of SI units?
>
>- Since the areal coverage of eclipses span a sizable fraction of the
>earth's surface, selecting an appropriate map projection is a challenge. In
>the 19th century, it seems that the British Nautical Almanac preferred the
>Mercator projection, which has qualities useful for navigation but which is
>a generally poor choice for eclipse maps. The French Connaissance des Temps
>and the American Ephemeris tended to prefer the orthographic and
>stereographic projections. Many recent eclipse maps have reverted to the
>Mercator projection, a puzzling and poor choice. I think the second ever
>eclipse map of 1676 got it right; the stereographic projection is the best
>overall projection for mapping the full extent of an eclipse. There are
>clearly several factors involved: ease of construction of a projection,
>purpose of the enclosing document (usually almanacs), cultural preferences
>(and latitude of home region?).
>
>If anyone on this list has special knowledge on the history of eclipse maps,
>or access to maps and research which might be added to or referenced in the
>archive of www.eclipse-maps.com, I'd appreciate hearing from you.
>
>
>best regards, Michael Zeiler
>Santa Fe, New Mexico
--
Dr. Barbara J. Becker
History Department
200 Murray Krieger Hall
University of California, Irvine
Irvine California 92697
http://eee.uci.edu/clients/bjbecker
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