When the sun is not normal to the plane containing the cannisters, {HEAD ~ the near cannister} is shaded from {TAIL ~ direct sunlight} and the far cannister is exposed 
is shaded from
When the sun is not normal to the plane containing the cannisters , { HEAD ~ the near cannister } is shaded from { TAIL ~ direct sunlight } and the far cannister is exposed
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH