NightHemisphere
✖
NightHemisphere
is a two-dimensional GeoGraphics primitive that represents the half of the Earth currently in darkness.
Details

- datespec can be a DateObject or a string that resolves to a date.
- A date without explicit time zone is assumed to use $TimeZone.
Examples
open allclose allBasic Examples (2)Summary of the most common use cases
Shade the part of the Earth currently at nighttime:

https://wolfram.com/xid/08u8y3aemw7wf9i-5qpdl

Show the unilluminated part of the Earth on the summer solstice, using red lines to denote the Arctic and Antarctic Circles:

https://wolfram.com/xid/08u8y3aemw7wf9i-sgaocv


https://wolfram.com/xid/08u8y3aemw7wf9i-ruv10t

Scope (3)Survey of the scope of standard use cases
NightHemisphere[] gives a plot for the current date and time:

https://wolfram.com/xid/08u8y3aemw7wf9i-0lx5yq

Using Now explicitly gives the same result:

https://wolfram.com/xid/08u8y3aemw7wf9i-km7gw

Illustrate changes in the unilluminated hemisphere at different times of day and year:

https://wolfram.com/xid/08u8y3aemw7wf9i-qskghr

Specify dates in other formats:

https://wolfram.com/xid/08u8y3aemw7wf9i-hia2p9


https://wolfram.com/xid/08u8y3aemw7wf9i-g75nnt

Properties & Relations (2)Properties of the function, and connections to other functions
The terminator line separates the day and night hemispheres:

https://wolfram.com/xid/08u8y3aemw7wf9i-g4x2nh

For a spherical model of the Earth, the night hemisphere is a geo disk:

https://wolfram.com/xid/08u8y3aemw7wf9i-6cllvd


https://wolfram.com/xid/08u8y3aemw7wf9i-vfst5w


https://wolfram.com/xid/08u8y3aemw7wf9i-rc2p3d

The true night hemisphere and approximate darkness geo disk differ slightly when using an ellipsoidal model of the Earth:

https://wolfram.com/xid/08u8y3aemw7wf9i-xev9gr

Wolfram Research (2014), NightHemisphere, Wolfram Language function, https://reference.wolfram.com/language/ref/NightHemisphere.html.
Text
Wolfram Research (2014), NightHemisphere, Wolfram Language function, https://reference.wolfram.com/language/ref/NightHemisphere.html.
Wolfram Research (2014), NightHemisphere, Wolfram Language function, https://reference.wolfram.com/language/ref/NightHemisphere.html.
CMS
Wolfram Language. 2014. "NightHemisphere." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/NightHemisphere.html.
Wolfram Language. 2014. "NightHemisphere." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/NightHemisphere.html.
APA
Wolfram Language. (2014). NightHemisphere. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/NightHemisphere.html
Wolfram Language. (2014). NightHemisphere. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/NightHemisphere.html
BibTeX
@misc{reference.wolfram_2025_nighthemisphere, author="Wolfram Research", title="{NightHemisphere}", year="2014", howpublished="\url{https://reference.wolfram.com/language/ref/NightHemisphere.html}", note=[Accessed: 11-July-2025
]}
BibLaTeX
@online{reference.wolfram_2025_nighthemisphere, organization={Wolfram Research}, title={NightHemisphere}, year={2014}, url={https://reference.wolfram.com/language/ref/NightHemisphere.html}, note=[Accessed: 11-July-2025
]}