GeoHemisphereBoundary
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GeoHemisphereBoundary
is a one-dimensional GeoGraphics primitive that represents the boundary line of a hemisphere of the Earth centered at the current geo location.
represents the boundary line of a hemisphere centered at the location loc.
Details

- The boundary of a hemisphere is a line contained on a plane that goes through the center of the Earth. Hence this line is a great ellipse.
- The location loc can be specified as latitude and longitude coordinates {lat,lon} in degrees, as GeoPosition[{lat, lon}], or as named entities Entity[…].
Examples
open allclose allBasic Examples (2)Summary of the most common use cases
Scope (2)Survey of the scope of standard use cases
The boundary of the hemisphere around your current geo location:

https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-bebh3k

The boundary of the hemisphere around a particular location, specified in several possible ways:

https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-xukzlc


https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-v3n7fy


https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-yilyho


https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-6n2wvd


https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-gc99bt

Properties & Relations (4)Properties of the function, and connections to other functions
GeoHemisphereBoundary[loc] is the boundary of GeoHemisphere[loc]:

https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-k252rd

DayNightTerminator[date] is equivalent to GeoHemisphereBoundary[loc] for the location having the Sun at its zenith at the given date:

https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-m009xg


https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-s2v6kj

This is the geo location that has the Sun at its zenith at that moment:

https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-h0dkti


https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-tv9koy

GeoHemisphereBoundary always represents a great ellipse:

https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-mbi0nj
Select some points on the hemisphere boundary and construct great ellipse segments among them:

https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-w7xuyc
These two curves exactly coincide:

https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-cagr7c

The hemisphere boundary does not coincide, however, with geodesic or rhumb line segments:

https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-48kcj0

https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-poguhy

Due to the small eccentricity of the Earth, the geodesic segments approach the great ellipse quite well:

https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-63n84k

GeoHemisphereBoundary is the limit of infinite height of GeoVisibleRegionBoundary:

https://wolfram.com/xid/0jvocx6d4m5qzlds92x4-cvjmqi

Wolfram Research (2015), GeoHemisphereBoundary, Wolfram Language function, https://reference.wolfram.com/language/ref/GeoHemisphereBoundary.html.
Text
Wolfram Research (2015), GeoHemisphereBoundary, Wolfram Language function, https://reference.wolfram.com/language/ref/GeoHemisphereBoundary.html.
Wolfram Research (2015), GeoHemisphereBoundary, Wolfram Language function, https://reference.wolfram.com/language/ref/GeoHemisphereBoundary.html.
CMS
Wolfram Language. 2015. "GeoHemisphereBoundary." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/GeoHemisphereBoundary.html.
Wolfram Language. 2015. "GeoHemisphereBoundary." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/GeoHemisphereBoundary.html.
APA
Wolfram Language. (2015). GeoHemisphereBoundary. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/GeoHemisphereBoundary.html
Wolfram Language. (2015). GeoHemisphereBoundary. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/GeoHemisphereBoundary.html
BibTeX
@misc{reference.wolfram_2025_geohemisphereboundary, author="Wolfram Research", title="{GeoHemisphereBoundary}", year="2015", howpublished="\url{https://reference.wolfram.com/language/ref/GeoHemisphereBoundary.html}", note=[Accessed: 10-July-2025
]}
BibLaTeX
@online{reference.wolfram_2025_geohemisphereboundary, organization={Wolfram Research}, title={GeoHemisphereBoundary}, year={2015}, url={https://reference.wolfram.com/language/ref/GeoHemisphereBoundary.html}, note=[Accessed: 10-July-2025
]}