Night Hemispheres in Mathematica.

hemispheres.mma

(* set geography data server *)
server := "http://www.staremapy.cz/naturalearth/`1`/`2`/`3`.png"

(* plot *)
GeoGraphics[{GeoStyling[Opacity[0.5], GeoServer -> server], 
  NightHemisphere[]}, 
 GeoBackground -> GeoStyling["ReliefMap", GeoServer -> server]]

(* more simple graph *)
GeoGraphics[{NightHemisphere[Now], Red, Point[$GeoLocation]}]

(* global night hemispheres *)
GeoGraphics[{
  GeoStyling[Opacity[.5]], NightHemisphere[],
  RGBColor[0.5, 0., 0.], Thickness[0.007], PointSize[.02],
  Point[$GeoLocation], GeoPath["ArcticCircle"], 
  GeoPath["AntarcticCircle"]
  }, GeoRange -> "World", GeoProjection -> "LambertAzimuthal", 
 GeoBackground -> GeoStyling["ReliefMap"]]