In the path of Mars against the background stars shown in Figure 2-2, the planet appears from Earth to move in a loop, moving westward for a period of time. In the 2012 loop, what is the angle between the Earth-Sun line and Earth-Mars line when the planet is halfway through the retrograde motion, in late February?
A) 180°
B) It can be any angle.
C) 0°
D) 90°

Question

In the path of Mars against the background stars shown in Figure 2-2, the planet appears from Earth to move in a loop, moving westward for a period of time. In the 2012 loop, what is the angle between the Earth-Sun line and Earth-Mars line when the planet is halfway through the retrograde motion, in late February? 
A) 180° 
B) It can be any angle. 
C) 0° 
D) 90°

Quizplus · Accepted Answer

The Answer of In the path of Mars against the background stars shown in Figure 2-2, the planet appears from Earth to move in a loop, moving westward for a period of time. In the 2012 loop, what is the angle between the Earth-Sun line and Earth-Mars line when the planet is halfway through the retrograde motion, in late February? 
A) 180° 
B) It can be any angle. 
C) 0° 
D) 90°

In the Path of Mars Against the Background Stars Shown