Plot the Paths of Shadows Cast by the Sun 

Plot the end points of the shadows of the Sydney Opera House every hour between one hour after sunrise and one hour before sunset.

In[1]:=

X {location, height} = Entity["Building", "SydneyOperaHouse"] /@ {"Position", "Height"}

In[2]:=

X time = DateObject[{2014, 5, 1}, TimeZone -> LocalTimeZone[location]];

In[3]:=

X sunrise = Sunrise[location, time, TimeZone -> LocalTimeZone[location]]

In[4]:=

X sunset = Sunset[location, time, TimeZone -> LocalTimeZone[location]]

In[5]:=

X shadowEndPoints = With[{sp = SunPosition[location, DateObject[#]]}, GeoDestination[ location, {-height/ Tan[QuantityMagnitude[sp[[2]], "AngularDegrees"] Degree], sp[[1]]}]] & /@ Range[AbsoluteTime[sunrise] + 3600, AbsoluteTime[sunset] - 3600, 3600];

In[6]:=

X len = Length[shadowEndPoints];

In[7]:=

X GeoGraphics[{GrayLevel[0.5], Line[GeoPosition[ First[#] & /@ shadowEndPoints]], {Blend[{Red, Blue}, (# - 1)/(len - 1)], Line[{location, shadowEndPoints[[#]]}]} & /@ Range[len], Red, Point[location]}, GeoRangePadding -> Quantity[1/16, "Miles"]]

Out[7]=